netzerolife

So Long and Thanx for all The Fish!

2011-08-30T20:10:00.000-07:00

Well, it's about that time, time to close down this blog and admit defeat. I had a look at my stats today and I've got around 7000 page views for all history. The blog has been running for about 3 years, so that is a pretty poor showing. And people rarely submit comments. According to The Lovely Wife, to get page views and comments, you need to go to other people's blogs and comment there. I've done that with a few, listed in the blog roll, but I've not had much success in attracting a readership. There are also not many blogs out there that generate the kind of content I've been trying to generate, which I suppose is no surprise, given the lack of readership I've had. I suppose another factor is my tendency to become technical and include math. Most people would rather get a root canal than try to understand math.

I suppose I could rant here about all the attention (and investment) given to infotainment devices and various other IT toys, but I will decline. Since I understand why. It is far more interesting to talk about the latest Apple toy than about some energy efficiency improvement. I bought an iPad for my mother this spring and boy was it slick! Oh well.

As a practical matter, I don't have anything in the pipeline to report on. The system remodel we did was one of those relationship-threatening jobs that people talk about. Now I know they really exist. The results actually look pretty good, though we did miss a couple things. But I am not about to put them in. I have sunk enough money in this house and irritated The Lovely Wife too much. I have a few small items:

Reinsulate the solar thermal tank with aerogel.
Insulate the HRV system because the architect screwed up and put them in uninsulated space. Probably I'll do some temperature measurements first to make sure more insulation is required.
Maybe put in some quieter exhaust fans in the bathroom and laundry room with humidity sensors.
Maybe put in a 220V timer on the hot tub, so I don't have to manually turn it off and on.
Maybe put in a solar thermal energy monitoring system, so I can get data on how much energy the solar thermal system is generating.

In retrospect, this is a healthy list of stuff. But since nobody seems to care about it, there is no point in continuing the blog.

So...in the immortal words of Douglas Adams:

Nissan Leaf

2011-08-23T17:25:00.000-07:00

I was out of town for July and most of August, so I did not have an opportunity to post. But just before I left, at the end of June, our Nissan Leaf arrived. They originally told me that it would come in July, and I told them I would rather have Sept. but then they bumped it up to June so they could accrue the revenue in Q2.

The purchase experience was one big ripoff. Nissan assigned me Nissan of Sunnyvale as my dealer. I arrived in pouring rain, and the sales guy ran me through the features of the car, then we took a test drive. The Leaf accelerates really nicely, it is very peppy and drives like a sports car. That sporty feel will make it popular with young drivers, and it comes at a price that is less than half of the Tesla. Back at the dealership, they took me to the finance guy. And he sort of worked me over, managed to extract a whole bunch of extra money for "scheduled maintenance". Electric cars really have no need for that, but somehow, after a long and difficult day at work, I let myself get duped. I had heard vague rumors that Nissan of Sunnyvale ripped people off, but it didn't sink in.

Above is a picture of the car. It's a hatchback, but there seems to be enough leg room in the back seat. I took 3 colleagues out to lunch, and the car behaved respectably. Enough acceleration, even with four engineers in it.

Below is a picture of the instrument display:

The car has three display areas, one immediately behind the steering wheel, one in the driver's line of vision with the speedometer, and a LCD where the nav system shows maps, in the middle of the dashboard. This display is behind the steering wheel and is showing that the car has 117 miles range, the parking brake is on, and it has 526 miles on it already. When you start the car, it plays a little Japanese themed tune, and fans the two colored displays on both sides, like a Japanese fan. Cute, but after a while it may get old. Fortunately, they have a collection of tunes you can have the car play, so it's possible to change. Maybe an aftermarket opportunity here, like cellphone ring tones 8 years ago?

Our charger comes from the EVProject, which is run by Blink. Above is a picture of the charger. We obtained the charger for free, as reported here. Sprig Electric from San Jose installed the charger while I was out of town. The charger is supposed to connect to the network via wireless LAN and report data from the car to the EVProject web site. My access point is protected with WEP2 and my wife didn't know where the WEP key was, so the charger remained unused. She used the 120V charger that comes with the car and, surprisingly, it mostly worked fine. If the battery is about half depleted, the car can recharge in 6 hours on the 120V charger.

Yesterday, I attempted to configure the network connection and ran into some problems. The unit found the DHCP server OK, got a DNS server address, and was able to obtain an IP address, but it still failed to make a connection. I called up Blink and they said that I had to bring down the firewall on my router and bring it up again. Fortunately, most computers these days have individual firewalls, so I had no problem with this. I would never, ever put my computer on the Internet without a firewall, it would be infected with malware in 5 minutes. After I did that, the connection was established and I could bring up the firewall again.

But yesterday evening, my wife told me that she was being thrown out of the network around every 15 minutes, which is exactly the reporting interval for the Blink. So something still isn't right. I called again today, and the customer service rep told me that the Blink had stopped reporting as of 12 midnight, and, after checking my wireless router's model number, that they would probably need to provide me with another access point. I suggested they might want to use Google's WiFi network, but they said no. Google runs a city wide WiFi network in Mountain View. Anyway, I have no objection if they want to give me another access point, so long as they don't insist on tuning it to the same channel. That would result in interference. Also, I want it protected with WEP2 at minimum and possibly even EAP/802.1x. We'll see.

All in all, I'm pretty happy with this car, despite the ripoff purchase experience. And my wife is even happier. I suspect that she may in the end be the main driver, though it is a much better fit for my commute. She has a 120V plug in at her work, whereas I don't, so it seems to make much more sense for her to use the plug-in Prius. But she thinks it is too big, and she likes the Leaf because it reminds her of the Fiat 500 she had when she was at the university, size-wise that is. It's a far stretch otherwise. The Fiat 500 had lousy acceleration, cheesy interior fixtures, and a primitive instrument panel. The Leaf is a class act, really nicely outfitted, with much more than anyone could need.

Retrospective on System Remodel

2011-08-22T21:08:00.000-07:00

This post is a retrospective on what I think I've learned by the system remodel we did on our house over the last year. First a brief review. Our goals were to reduce the carbon footprint of the house as much as possible, hopefully to net zero energy, primarily by somehow reducing gas usage for space heating and hot water. We started out with a solar thermal hot water system that completely removed gas usage for heating in summer but required gas for an old tank-based gas heater in winter. We succeeded in completely eliminating gas usage for hot water though an on-demand electric hot water heater as backup, offset by solar PV. We did not succeed for space heating, however. Our original plan was to install a geothermal heat pump and also offset as much as possible of the geothermal heat pump with solar PV. As it turned out, we abandoned the geothermal heat pump for reasons discussed below. We did not have enough solar resource on our roof to offset the electricity usage anyway, or, at least, we could either offset an electric car or the geothermal heat pump but not both. We are able to offset the on-demand electric hot water heater, but, in the end I estimate that we will still draw around 1000 kwh from the grid with an electric car and use around 250 therms of gas for space heating and cooking (cooking only amounts to around 1 therm a month).

Of course, whether we really succeeded in reducing our carbon footprint so much remains to be seen, I'll be measuring our energy usage over the next year (including some new measurements on exactly how much solar electricity we are generating thanks to the new Tigo MPP balancing system and monitoring tool). But I think we did learn some important lessons about the process of green remodeling and the technology available today. Below, I've listed some lessons I think we learned from our system remodel.

Geothermal heating and cooling systems are a ripoff in Northern California
We paid $9K to get a design for our geothermal system before pulling the plug. Cost was one reason we decided not to do it. The entire system was originally spec'ed at $60K and it surely would have grown by at least 20%. Recently I spoke with a couple who moved into our neighborhood from upstate New York. A good friend of theirs runs a geothermal contractor there and they said that $9K was how much one would pay on average for an installed system, and the geothermal contractor didn't need any expensive design. Why is geothermal so expensive in northern California? Hear are some speculations:

There are only three geothermal design firms in northern California, one in Santa Rosa, one in Sacramento, and another one I know not where. With that little competition, they can charge as much as they want.
Given the more complex geology of California, the state needs to regulate it more and drilling is more complicated than in New York. But 10X more complicated?
Geothermal HVAC systems are priced as a premium product, for $5M houses in Woodside and not for your average - but still quite pricey by standards of the rest of the country - house.

It seems like there is a real market opportunity for operators in the rest of the country to expand into northern California and start taking some business.With a 10x price differential, a contractor could move in and undercut the competition. Even better, a nationwide contractor (if such a thing could ever exist) could get economies of scale and achieve even lower prices (but see below for caution).

Geothermal technology today is designed for cold climates and is not well integrated with newer HVAC technologies like HRV
The system they were proposing to put into our house had a huge 80 gallon buffer tank connected directly up to the ground loop. The system was designed so that the heat pump would run flat out, cooling or heating the buffer tank until the temperature was uniform, then shut down. Though they never really told me why the buffer tank was needed (despite my asking), I suspect it was because the pump could not withstand intermittent operation. If there were no buffer tank, in our mild climate, the pump would end up going off and on frequently. Since it would have had to start pulling 3 x 300 ft. columns of fluid every time it started, the pump would probably have worn out sooner.

On top of that, we would have needed a whole second air handling system and ducting, parallel to the HRV ducting we were installing, for the air conditioning (we have hydronic radiant for heating). I asked why the second ducting system was necessary and they just shrugged. Our house is designed in such a way that it would have been impossible to fit in a second ducting system. Fitting the HRV ducting was a challenge in and of itself. The original forced air heating had ducting under the house, but that was removed when we had radiant installed. It simply isn't possible to find an integrated HRV/geothermal air handler.

But recently I ran across an article on ductless air conditioning systems. The article was written with air source heat pumps in mind, but it could equally well apply to ground source heat pumps. The basic idea is to run the refrigerant lines from the heat pump to small air handlers (basically fans) in each room. Since the refrigerant lines are much smaller, this would have worked well in our case. We could have run two lines to the two HRV systems on opposite sides of the house, and installed heat exchangers there. Except the HRV systems aren't designed with outside assistance for heat exchange...Oh well.

Embedded Global Warming Potential (GWP, Climate Change Potential, CWP?) does count
When I started the project, I wasn't convinced the embedded GWP was such a big issue. By this I mean the carbon equivalent embedded in the products or processes used to do the work. My focus was reducing the carbon footprint of the building over the long term, since I figured that the building would be around much longer than I will, and reducing the carbon footprint over that long a time period would result in big gains. What I missed was that some treatments with excellent carbon footprint reduction potential have such large GWP themselves that they can equal or exceed the carbon footprint of the carbon-based energy use they eliminate. Closed cell foam is an example. While I probably would put closed cell foam in anyway if I were doing the job again, I think I might have put in less (just the ceiling for example) and done the rest in open cell foam which has far lower GWP potential (but see below).

Architects, even those claiming expertise in green building, are by and large mostly interested in aesthetics and not particularly concerned with the detailed engineering and fact-checking necessary to achieve really energy-efficient buildings
We originally selected our architect because one employee of the firm was involved with me in a local city-wide sustainability initiative, and also because I had seen a house designed and built by the architect's firm that had a very high Green Point rating. This employee left the company around a month after we started the design process, and the owner of the firm, who we continued working with, exhibited less than diligent attention to our remodel. He tried to convince us of dubious enhancements such as a solar hot air heater. When we need heat here in northern California, it is usually raining and cloudy. Such technology is more appropriate for climates like in Boulder, Colorado, where they have very cold but sunny days in winter. He also routed our HRV ducting through uninsulated attic space, which very likely will substantially reduce the amount of heat recovery we will get. From a practical standpoint, this was probably the only way to get the ducts routed, but he could at least have then recommended we insulate the ducts with additional insulation afterward. As it was, I didn't realize the error until the end of the job, by which time, we were so fed up that I decided wait and install it myself later if heat loss from the ducting becomes an issue. I had to spend a substantial amount of time researching energy efficiency technologies myself on the Internet, because the architect simply disappeared after drawing the initial plans. After that, the project manager (aka general contractor) and his assistant took over, and they were even less knowledgeable and interested than the architect. On the other hand, I think if we had been building a 3000 sq. ft./$5M house from scratch in Los Altos Hills, the architect would have been all over it, with passive solar, etc., and we would have been extremely satisfied with the result.

So I have the impression there is a kind of market hole here of professionals who are both knowledgeable about how to do plans for extensive remodeling construction and interested and engaged enough in the technology of energy efficiency and renewable energy that they are willing to do the detailed fact checking necessary to ensure that a project accomplishes its energy reduction goals. I would have appreciated some discussion of choices, with some detailed analysis of what they could accomplish for my home. I got none of that, except as I calculated it myself. There is now software for doing these kinds of calculations but so far as I can determine, the architect we worked with didn't have access to it, or, if he did, had little interest in using it on our job.

Construction "professionals" are not interested in green technology and energy efficiency, even when told that energy efficiency is the top priority, since they have been so ingrained to simply look at cost.
We constantly ran up against this problem with our project manager. He was always looking for the lowest bid came from a subcontractor that knew little or nothing about green building. For example, I specifically told him that I wanted a 7 kw system with MPP balancing. His assistant came back to us with a collection of bids from small contractors for systems sized at around 5 kw, and none of them had MPP balancing. The best I could get was one guy who proposed a 6 kw system using microinverters (I've discussed the problems I see with microinverters here). At least, this guy was a professional. One of the bids was from a nonprofit who sends "volunteers" up on the roof. Considering that we had a roofing professional fall from our roof and injure himself, I wanted nothing to do with that one. The reason they came back with these systems was because they were trying to hit a cost objective rather than the energy generation specifications I set out for the project. I finally had to tell the assistant to call Tigo and ask them for recommendations about solar contractors. That's how I got connected with REC and they did a fantastic job.

Neither the project manager nor his assistant kept a close eye on the subcontractors. They never visited the job except to let the subcontractors in and lock up at night. Of course, I know that contractors are usually managing 3 or 4 jobs at once but there were a couple times when we had a specific green technology installation, like with the HRV or the thermal bridging treatment, where serious problems could have been avoided if the project manager had shown more interest and diligence in actually checking up on what the subcontractors were doing during the job rather than leaving it up the the manager of the company doing the subcontracting.

Most construction technicians know nothing about green building techniques and care even less.
After all, they are getting paid by the hour, and, unlike professionals, they don't take much pride in their work. It is just a job (note that this was not always the case, people in building trades used to take much more pride in their work 50 years ago). A friend in construction told me that a survey showed something like 60% of most people working in construction today have had a substance abuse problem, and that the overwhelming majority did the work because they didn't think they could do or couldn't do any other. And, to a large extent, I believe it is not the fault of the people in construction, I'm sure they would in the end rather feel good about the work they do. Construction technicians have no incentive to upgrade their training, so many are operating on knowledge obtained years ago, which doesn't reflect the latest results of building science. There is nobody paying them to take classes in the latest technology, and, because they really don't have much interest in their jobs except to earn money, they're not about to spend any time or money trying to upgrade their skills on their own. I believe this is because, in the last 40 years, the increasing right-wing tilt to the American political and social scene has devalued the contribution and importance of skilled labor at the expensive of massively overcompensated executives. Even though many construction technicians earn good salaries, they don't take much pride in their work because society doesn't really value it.

In my opinion, this point is the most serious problem for politicians who propose government programs to increase energy efficiency in the existing housing stock (commercial buildings are different, there a clear bottom line case for efficiency and people being paid to oversee the process with the interests of the building owner at heart causes better results). Even if the money were there, the knowledge simply isn't. I checked the curriculum at our local community college and there are only three programs for people in the trades to upgrade their skills, with only three or four courses per program. There are no programs in solar PV or solar thermal installation, proper building insulation, or HRV installation. If you want to learn about solar PV installation, you need to drive to Hopland and take courses at the Solar Living Institute. The Solar Living Institute has some excellent programs, but I don't understand why the knowledge for green building isn't being taught more widely. If we really want to achieve an 80% reduction in carbon footprint of our society by 2050, we have to work with the housing stock we have.

So there you have it.

Heat Control

2011-06-22T20:40:00.000-07:00

The last few days here in Silicon Valley we have had temperatures in the upper 90'sF. Today, it cooled off substantially, but the heat gave me an opportunity to see how our newly re-insulated house performs in hot weather.

What I did was open all the windows up at night and let the house cool down. After the first night, the downstairs cooled down to around 70F, the upstairs to around 72F. After the second night, the downstairs cooled down to around 72F and the upstairs to around 74F. It seems that the thermal mass of the house didn't shed much heat during the night without some moving air (like with exhaust fans) to encourage it.

During the day, I closed all the windows with the exception of the skylight window. The house was not uncomfortable. The upstairs was at 82F the first day and 84F the second. I can say that this performance is much better than we would have seen without having done the reinsulation. The upstairs would have been into the upper 80's.

Today, I tried closing all the windows and running the HRV all day, but it did not help much. The inside of the house was in the 80's, up to 81 upstairs, though the outside temperatures were way down, in the mid to lower 70's. I wonder if that had to do with the fact that the ducting for the HRV's runs through uninsulated attic, which could be expected to heat up substantially?

I hope to find out in the fall, when I am planning to install some wireless sensors to see. If it turns out to be so, I'll look into heavily insulating the HRV ducting.

Plastic Packaging

2011-06-02T20:43:00.000-07:00

Well, it seems retailers are finally doing something about plastic packaging. If you recall from this post, my purchase of new LED and CFL lights for our new light fixtures caused a mound of plastic packaging to materialize on the Buddha room floor by the time I had finished installing them.

As it turns out, the increasing price of oil makes the plastic clamshells that are ubiquitous in retail more expensive. So retailers are working with manufacturers to reduce the clamshells and use more paper, which is cheaper, renewable, and recyclable. This article in the New York Times (possibly behind a paywall) has more.

And it is about time too. Some of these clamshells are so thick that you need a pliers to open them.

Finished

2011-05-26T20:15:00.000-07:00

Well, after 11 months, our system remodel has drawn to a fitful conclusion. The contractor spent the last month going through the "punch list" of items like cracks along tile/wall joins that needed fixing. In the end, I simply left a couple of small items involving paint finishing because it was time to call it done. They still need to send the final bill with my contingency returned. Now comes the interesting part, measuring how well the improvements we made work.

I have one data point already. Usually for the month of April our electricity bill showed something like minus 6 to plus 12 kwh usage, depending on the amount of sun. This year, we had a whopping minus 500+ kwh, the impact of our new, more-than-twice-as-large solar PV system. Since we don't yet have our Nissan Leaf, the power is simply going back into the grid. We've just about eliminated the big bill from Feb. when we had to turn the electric floor heating on in the sunroom and upstairs bathroom over a weekend to reduce the amount of moisture from wet drywall mud and we had no solar panels. Unfortunately, the Leaf won't show up until July so we will have a couple more months of large surpluses before we start balancing out.

Naturally, the solar thermal hot water system is cranking too. I turned the temperature down on the tank to 130F to avoid damage to the Stiebel-Eltron electric on demand hot water heater. The company claims it is rated up to 131F. I am wondering if I can instead simply turn the electric hot water heater off for the summer and keep the solar thermal tank at 180F, or if that temperature will damage the electric heater when it is off, but I probably won't try it because the Stiebel-Eltron was expensive. Not that it matters for the water we use. The mixing value brings the temperature down to 120F anyway, but keeping the tank extra hot reduces the overheating strain on the heat transfer fluid, and reduces the probability that a couple days of cloudy weather will reduce the tank temperature below 120F where the electric on-demand heater will cut in. I still need to reinsulate the tank, since the plumber destroyed the fiberglass batt blanket I had installed. I am planning on using aerogel insulation. Should be interesting, aerogel is a new material with some promise, but still pretty expensive. Fortunately, I don't need much for the tank.

In a few weeks, I want to write a retrospective about the job, and also do a piece about reinsulating the solar tank with some pictures I'll probably also have something to say when our Leaf arrives. However, inevitably, the frequency of my postings will be reduced now that I don't have much to blog about. Thanx to all my loyal readers who have pushed my page views up from single digits to low double digits.

New LED Lights

2011-05-01T20:49:00.000-07:00

One of my very first posts (here, published in November, 2009) was on a new LED light bulb. Though it was advertised as a 60 watt equivalent, it is 40 watts at best. These bulbs being what they are (namely, that they last 50 years) I still have both bulbs in light fixtures in areas that don't require much light.

Last weekend, I was busy collecting track light fixtures and bulbs for our new track lights at Home Depot and I ran across new LED bulbs that are also rated at 60 watt equivalent, in a indoor spotlight form factor. These bulbs are, like the ones I bought 2 years ago, not cheap: $50 apiece, but they are supposed to last 50 years, for $1/year of light. Contrast that with CFLs, which run around $10 and are supposed to last for 5-8 years, for around $1.25-$2/year, and the LED lights seem a relative bargain. But, having been once burned, I was twice shy so I took the plunge on three: two large spots and one small one.

The large spots are Ecosmart brand, marketed by Phillips but manufactured by Cree:

Unlike the Pharonx bulbs, these have a large plastic fitting around them, maybe a heat radiator?:

Here you can see it installed in one of the track light heads:

The bulbs might be ecosmart, but the way they are delivered was ecostupid. Here's the trash that was left over from one bulb:

I also bought a small spot, equivalent to a halogen bulb, for a pendant lamp for the upstairs front bedroom. Here you can see it next to the halogen bulb it replaces:

The halogen bulb is rated at 50 watts while the LED is rated at 5, for the same amount of light.

For the rest of the track heads, I bought a discount box of CFLs:

Strangely enough, I have to say I like the CFLs better. Contrary to what most people say, the light they give off is softly diffused and slightly yellowish, while the LED light is white and glaring, like normal halogen or incandescent spots. Since we use spots through out the house, not having them glare into your eyes when you happen look their way is important. CFLs don't seem to glare as much.

When I was done with my task of separating the bulbs from their packaging material and installing them, I was left with a big pile of trash:

That's three subpiles: film plastic, thicker plastic bubble wrap, and cardboard. Theoretically, it is all recyclable and we have good recycling in our town, but did they have to include so much?

Solar Fountains

2011-04-25T20:38:00.000-07:00

Every year during the Going Native Garden Tour, I get lots of questions about our solar fountains. We have a lot of water features in our garden. Since the key to making renewable energy practical is to reduce energy consumption, I didn't want to add additional base load to our big solar panels by having fountains that run all the time off of the AC grid. So I've spent the last 6 years or so working with solar fountains, and this post tells you a little about them.

I've found that there are basically three kinds of solar fountains:

Fountains in which the pump, solar panel, and water feature are completely integrated,
Fountains in which the panel and pump are provided as a kit, and you simply install them in a water feature,
Fountains that are made from bits and pieces that were bought for other purposes and need to be assembled and installed into the water feature.

All these kinds of fountains basically recirculate the same water, and need to be filled periodically because they don't have a connection to a water supply to replace evaporated water. I suppose it is possible to connect a fountain up to the domestic water supply, but it would really be a lot more complicated.

In the first category is what The Lovely Wife calls the "Christmas fountain", because I gave it to her for Christmas a couple years ago. It is basically a plastic birdbath with an integrated solar panel and pump:

These kinds of fountains are really simple to install and use. You just place the fountain out in the sun and fill it with water.

The second kind require you to build some kind of water feature around the fountain. Here you can see a nice little fountain The Lovely Wife built in the front garden, with a blue bowel on top of a column of flat rocks:

The pump and the solar panel come as a kit, you just plug them together and set the solar panel out somewhere where it will get some sun but isn't too obtrusive. That's the solar panel in the background.

The other two solar fountains in our yard are the third type. Here you can see them running full bore on a sunny day. The first picture is the big fountain on the side, the second is the small one in the back:

These started out as the second type, i.e. a kit, but in addition to the solar panel, they had batteries for running at night. Unfortunately, the batteries didn't last very long, so I removed them and wired the panels directly to the pumps. This required some creative wiring as you can see here:

I have the junctions in a couple of plastic Tupperware boxes to keep it from getting too wet. With the big fountain, I can hide the box behind a large fern, but with the small one, I can't. So I bought a fake rock under which I hide the Tupperware box. Here you can see the Tupperware box sticking out when the rock is upside down, and how realistic it looks when the rock is properly positioned:

The fake rock is always a big attention hit during the garden tour. Also, it acts as good habitat for lizards. When I lifted it up recently, there was a big lizard underneath.

The large, 18V fountain on the side has a big pump and a large thin film solar panel:

It's really wonderful, like having a brook in our yard. On sunny days, the sound attracts hummingbirds.

The smaller, 6V fountain in back has its wiring concealed under the fake rock. It also has a thin film solar panel and runs into a water barrel:

The DC pumps on all the fountains are really poorly made and usually last between 1-3 years before they burn out. But since they only cost around $20 apiece, it's usually not a problem to replace them, though I had a hard time finding a pump for the 18V fountain. Good, reliable pumps are almost 10x more expensive. Silicon Solar has both the cheap and the reliable pumps, and a line of pump kits including those with battery backup. They have a nice selection, but sometimes their service isn't so prompt. I had to cancel an order last year because they still didn't have stock in 6 months after I placed the order. But unless you feel comfortable ordering over the Internet from China or know German (there are some really nice but expensive pump kits from German web sites), Silicon Solar is probably your best bet. I suppose, from an environmental perspective, throwing away a pump every 3 years isn't a particularly good use of resources, but all the parts on the pump can be recycled, and we have especially good recycling in our city, so I've so far favored the cheap pumps despite the hassle factor of having to replace them (and also because until last year, small reliable ones weren't available, at any price).

The latest trend in the cheap pumps is to wire a capacitor across them so that the capacitor slowly charges when there is not enough sun to run the pump continuously. When there is enough charge, the pump turns over once and water spurts out.

Though it is still cold here in northern California, spring is really here now and the wildflowers are spectacular. This double rainbow appeared the other day, perhaps a sign that the mild but wet winter we had this year is finally over:

Earth Day Post: Is E85 Worth It?

2011-04-22T21:03:00.000-07:00

Today is Earth Day and so I thought I would post something about what the next step might be in our quest to reduce our carbon footprint to zero. We still need to buy gasoline for our plug-in Prius, especially when we take it out of town, so biofuels seems like one area where we might focus some attention. Our local paper recently had an article about a couple of Silicon Valley companies working on biofuels. One of them is Propel. They're working to get more E85 and biodiesel fuel dispensing pumps installed around the country, and soon will likely be opening a station in our city. Actually, we already have a biodiesel pump at a nearby (less than 5 miles) station, but our plug-in Prius doesn't have a diesel engine and there are, as yet, no diesel hybrids available in America (Citroen makes a limited edition model that they are now selling only in Europe). There are stations with E85 available in San Jose and Redwood City, but they are too far away for regular tanking up, even with our plug-in Prius which we usually fill about once a month and a half, unless we take it out of town.

E85 consists of 85% ethanol made from corn and 15% gasoline made from oil. Most automotive fuel in the US that is used by "gasoline" engines today consists of 10% ethanol and 90% gasoline. In addition to its value as a renewable, nonfossil-based fuel, the ethanol serves as an oxygenating agent, which is especially important in California where emissions from automotive combustion contribute to creating smog. Ethanol as an oxygenating agent reduces smog-forming chemicals in exhaust. The EPA wants to increase the percentage of ethanol to 15% in regular gas to reduce the amount of fossil carbon emitted by the transportation network. This is somewhat controversial right now, but most tests have shown the cars manufactured after 2001 can run without any modification and without any negative effect. Of course, this leaves the people with cars manufactured before 2001 with a problem if the entire fuel distribution network switches to 15% ethanol, but we've seen this movie before. When the US switched from leaded to unleaded gas in the 1970's, cars with older engines had to continue using leaded to lubricate the valves, or the driver needed to add something to a tank of unleaded. Retailers continued to sell leaded gas for a while, but have you seen any leaded for sale lately?

In fact, it is possible to fuel any recent vintage car with E85 or even E100 (100% ethanol) without any long term effect on the car. The manufacturers have eliminated rubber and plastic fittings that might be degraded by ethanol from the fuel lines, tank, and other fixtures in the fuel system. Nonmetal fixtures are degraded by gasoline too, just not as quickly, so removing them decreases the probability that the fuel system will experience a failure, which might be quite serious if leaking fuel catches fire. The lower energy content in ethanol does cause problems for the car's engine control computer, though. Because the car ends up using 30% more fuel with E85 than with E10, the engine control computer triggers the Check Engine light (that little light which looks like an oil can on most car dashboards, and comes on usually in rather mysterious and not very critical circumstances). The light stays on until it is cleared on the CAN bus (the car's control system bus) by a computer control plugged into a USB port somewhere in the front of the passenger compartment. So, in theory, we could use E85 without any modification to our plug-in Prius, if we were willing to drive around with the Check Engine light on all the time. There are also conversion kits for modifying the fuel control system so the engine computer doesn't report a fault when the car uses more fuel than the engine computer expects, so we could theoretically install such a kit when Propel puts an E85 station within convenient range if we wanted to avoid the Check Engine light problem.

Now, corn-based ethanol is really not the best choice for a renewable transportation fuel. Raising the corn and processing it to ethanol takes so much fossil based energy that E85 results in only a 20% reduction in life-cycle fossil carbon emission (rather than the immediate carbon emission from just using the fuel). And the ethics of using a food crop for transportation fuel when the world population is 7 billion and rising - and the amount of agricultural land isn't growing - is pretty questionable in my opinion. With cellulosic ethanol (ethanol made from plant waste and crops such as switchgrass that aren't used for food), the reduction can be much better, around 86%, according to Propel's website. Production facilities for cellulosic ethanol are gradually starting to come on line, but it will be many years before corn ethanol is completely displaced.

I did a quick calculation to see how much converting our plug-in Prius to E85 would reduce our direct carbon emissions. In the calcuation, I didn't take into account the life-time reduction, but rather just the immediate reduction of substituting fuel which is 85% nonfossil ethanol. My estimate on how much fossil carbon our plug-in Prius and the (as yet undelivered) Nissan Leaf charged from our new solar PV system will generate is 1.11 metric tonnes per year (see this post for more information on how I estimated our projected carbon footprint), and our total fossil carbon footprint was estimated at 2.81 metric tonnes per year. If we were to go with E85, we would reduce our transportation contribution by 85% to 0.167 metric tonnes per year, which looks pretty significant, for an overall fossil carbon emissions footprint of ~~2.417~~ 1.86 metric tonnes per year. But the impact on our percent reduction from our 2002 baseline would be rather small, from a 78% reduction without E85 to a ~~81%~~ 85% reduction with it. If we factor in the lifetime fossil carbon in E85, the reduction is even less, not even considering the issue of the food v.s. fuel choice.

My conclusion is that between the minimal carbon reduction, the hassle and cost of doing an E85 conversion (if we want to avoid the Check Engine light problem), and the ethical issue, conversion to E85 is not worth it at this time. This might possibly change when cellulosic ethanol becomes the baseline for E85.

It's Getting Very Near The End...

2011-04-20T20:40:00.000-07:00

We are now in that part of the construction job that feels like Zeno's Paradox. The contractor takes 5 months just to get started on the job, then another 2 1/2 to do the bulk of the work, then another 1 1/4 to do some finishing items, then gets stuck in a phase where every week, a few minor items are done, with the number of minor items completed gradually reducing...

Well, you get the picture. Speaking of pictures, here's one of the urbanite that replaced the concrete sidewalk:

The Lovely Wife filled the cracks with tumbled, recycled shower door glass, looks a little like tiny cubes of ice. Quite nice I think.

The gas fireplace is together, except for the door over the control box:

We tried it out briefly. It puts out an incredible amount of heat, and the fan is a bit loud, but we don't expect to be using it much (we didn't use the old pellet stove at all).

We replaced most of the lighting in the house. Here's what we put in the hallways:

It's nothing special, an Ikea Pult, but we like it and it fits in with our minimalist, more modern decor. The old lights were shiny brass with panes of glass like carriage house lights.

Unfortunately, the chandelier chains were too short, but the electricians hung them anyway:

I can't imagine where their common sense was with this. Also, as you'll note, one of the bulbs I bought didn't work, but still they hung it. This chandelier is a Varaluz Aizen made in the Philippines from recycled iron

The pendant lamp suffers from the same altitude sickness as the chandelier:

It's a Possini Euro Deco, in brushed nickel.

In two of the upstairs bedrooms which we use as workrooms, we put in sconces. These rooms formerly had spots in them, and were always dark. Now they are filled with light. Here's my office:

The sconces came out the best of our lighting choices.

And on that note, I'll finish this side excursion into interior decorating. I have a couple more posts on more serious topics brewing, but lately I've been so busy at my day job and preparing for the annual Going Native Garden Tour (the high point of the year for The Lovely Wife, who is an avid native gardener) that I haven't had time to post anything.

How to Get People to Adopt a Low Carbon Lifestyle?

2011-04-10T21:24:00.000-07:00

Well, our system remodel - projected to take 4 months but now at 10 months - is slowly grinding to a close. We keep finding odds and ends. The worst one was that someone at the general contractor bought an uninsulated door for our new HRV chase, which got installed this week. I can't understand why they would think that after paying so much money and suffering through so much disruption to reinsulate our walls, we would be happy with an uninsulated metal door that punches a hole in the thermal envelope of the house. But other items are slowly progressing, and this week we should have the electrical work and baseboards done, which should be sufficient for the inspector to approve the job and for us to move back into the house. The rest of the items - like replacing the door - we can do after we've moved back in.

Anyway, what I really wanted to talk about this week was something else. I got email a few weeks ago about a home visit program run by the local environmental group, Acterra. The email said something about doing home visits to help people reduce the amount of carbon emissions due to energy use. Now that I have been through about 10 years of working on this problem in our own lifestyle, I thought I could help other people too based on our experience. So I signed up for the training.

I'm not sure what I expected but I knew I was in the wrong place when everybody there was either retired, a student, or unemployed. The program requires two home visits a month which are supposed to run for 2 1/2 hours but realistically, it means sacrificing a day a month for the work. Considering that I have a full time job and am usually out of town for a week a month on a business trip, this was a time commitment that I simply don't have. I also didn't find that the program was a good match for my interests and skills. It involves doing stuff I am not good at, like plumbing, and lots and lots of paperwork. So from a personal standpoint, the program doesn't seem like a good match for me.

The program does result in some carbon and water savings, but the per-household savings are not large, on the order of "change out incandescents for CFLs", better than "unplug the cell phone charger" but not up there with "install solar PV on a power purchase program". The premise of the program seems to be that if people see savings on the order of a couple hundred dollars a year on their utility bills from various conservation measures, they'll become more likely to support larger policy changes to move society to a lower carbon, renewable energy future. There are a couple problems with this premise. First, the program is entirely voluntary, so the people who sign up for it are self-selecting. They are more likely to have environmental concerns to start with, so they probably would support policy changes to move to a low carbon society anyway. Second, the premise that cost savings should be the motivator for adopting energy efficiency and renewable energy is, in my opinion, misleading. There are some very low hanging fruits that are available, but they don't amount to much carbon savings. Once you've harvested those, you quickly come into the much higher branches of the tree, where harvesting the fruits costs money. We are not going to get to 80% carbon reduction by 2050 by saving money. This is one important point I've found out from our efforts over the last 10 years, which have, in fact, reduced our direct carbon footprint (house and car) by an estimated 80%, or will shortly. I can't do anything about my business travel, except quit my job, and we can't do much about purchases that have high embedded carbon content or that use lots of energy, except buy less. Since I enjoy my job, and we already don't spend a lot of money on stuff, we are working on the areas where we can.

To the extent that the environmental community has made this cost saving a major part of their message about carbon reduction, they have been misleading the public. The amount of money required to build our current, high carbon infrastructure is enormous, and it will take that much, if not more, to replace it. Take, for example, the Interstate highway system. Before 1950, it didn't exist. Now it does. Some huge amount of money went into building it, that came out of a societal consensus about a particular transportation option. In my opinion, rather than trying to sell people on energy efficiency because they can save a few hundred bucks on their utility bill, they should be taking straight:
- That if they don't start using energy more efficiently, it will be impossible to power society with renewables, and we will have to continue using carbon-based energy and nuclear power.
- That if that happens, we will see, every 20 years or so as has been the case up until now, radioactive contamination of large areas of land like around Chernobyl and Fukushima due to reactor malfunctions. These land areas then will need to be sacrificed for thousands of years until the radioactivity decays.
- That the carbon emissions from coal, oil, and natural gas will result in climate changes that will make a large part of the middle latitudes tropical or a desert for at least a thousand years and maybe more, eliminating any agricultural use. The result will be widespread starvation and a population crash.
- That the transition to a low carbon future will require the same amount of investment that we've put into the high carbon infrastructure we have now, but the result will be a world their children can live in with some comfort and prosperity.
The environmental community needs to get in the Tea Party's face about this, and Koch brothers too.

Acterra is a great group, they have lots of excellent programs, including one for training environmental activists, and I fully support them. I also think this program is fine for what it does, though it unfortunately just isn't a very good match for my personal circumstances. It will be especially helpful for low income people, since a couple hundred dollars saved on their utility bill may mean the difference between really making it and not. And it might even help a few middle income people too. But it is not going to convince people who are denying reality about the dangers of carbon-based energy.

Roof Comparison

2011-04-03T20:48:00.000-07:00

If you recall from this post, a picture of the roof after a below-freezing night showed a dense frost pattern, an indication that our insulation job was successful. I mentioned that I did not have a photo from before the closed cell foam insulation. On Friday, I was browsing around looking for a photo of the inside for another reason, and I found a couple of photos of the roof which I took on a cold winter morning in 2008. Here they are:

You can see how the frost is thin and patchy. Some of the patchiness near the top may be from melting but the bottom hasn't had any sun yet. Compare that to this photo, which is from the previous post:

Here the only thinner spots are where the roof rafters are causing thermal bridging. Next winter, I'll try to get some better pictures.

We are now coming into the last week (hopefully) of our System Remodel, after almost 10 months of work. The solar PV system seems to be functioning well, I've been watching it push the meter backwards. At the peak in the afternoon, it seems to be putting out around 4.5 kw, which is just shy of the 4.7 kw that the panels on the west side of the roof are rated at. The around 5% difference is probably due to the inverter efficiency, possibly also due to some shading on the panels on top of the dormer. We are back on solar thermal hot water, after I discovered that the plumber had removed the temperature probe from the control port in the solar thermal hot water tank. This was why the tank temperature wasn't registering over 74F. Fortunately, it being winter, the tank didn't get hot enough to trigger the overpressure value, though it did cause the solar pumps to be on much longer than they normally would have. The big question right now is: will the Stiebel-Eltron tankless heater handle the extremely high (up to 180F) water temperatures in the summer without triggering the over heat breaker? We have email into Stiebel-Eltron about it. I am also planning on having Sunwater Solar over to check the solar hot water system. It has been two years since we had it installed, and we missed the annual maintenance last year because the house was torn up.

Of course, we won't know how effective the insulation was until next winter when we start heating again. Temperatures here in California were in the 80F's last week, hot for this time of year. Over the weekend, the temperatures cooled down some. Most of our weekend was consumed by working to get the garden in shape for the annual Going Native Garden tour. I'm responsible for the solar fountains, and I can say that as of today, they are all running again. Tune into our sister blog at Town Mouse/Country Mouse for more on the Going Native Garden tour.

Job Progress Update

2011-03-27T21:16:00.000-07:00

Our system remodel is slowly grinding to a conclusion, after 9 months.

This week on Monday, REC came and replaced the Tigo maximizer unit, which wasn't working, and turned the solar PV system on. It rained all week, so I did not get to see whether the PV system was generating any electricity. Today it was sunny, but the inverter still wasn't showing anything on the display, so I think they still haven't quite turned it on yet. The meter also wasn't running backwards. I'll call REC tomorrow.

Last week, my friend Karl and I took the old gas fired tank heater over to ReusePeople in Oakland. They sell recycled building materials. I donated the gas fired heater, as well as a pile of tile that was left over from previous jobs, and three boxes of various sized light bulbs for fixtures we no longer have. The new on-demand hot water heater seems to be working OK now, here it is:

Last week, it blew out two of the three circuit breakers and some circuit breakers on the heater itself. Paul came and checked it, reset the breakers on the heater. The plumber had set the temperature to 140F, which was way too hot. 120F should be enough, which, as you can see, it is now set to. In the photo, you can see the insulated hot water pipes going to the solar tank closet on the left. Both lines are hot, since the backup heater is supplementing the solar tank. I think the uninsulated line is the drain. The two armored cables are the electric lines. These are some pretty hefty lines: 3 circuits at 240V/20 amps.

I also discovered today that the plumbers had, early in the job, taken the temperature probe out of the solar hot water tank. The temperature measurement for the tank never got above 80F, so the pump has been on a lot, even cooling the tank down when it was hotter than the collector. Fortunately, the tank temperature never runs up above about 115F in winter. In the summer, it could easily have run much hotter, and blown out the pressure release valve. Everything seems to be working fine now, we had sufficient hot water during the week when there was no sun, and today with sun as well.

I will need to reinsulate the solar tank though. The plumber slashed through the kraft paper facing of the fiberglass batt when he installed the connection to the on-demand heater, so it was not possible to tape it back together. The fiberglass was spilling out. I had to discard the insulation, as well as that which was around the old gas-fired tank downstairs.

Because of the way the window upgrade was done in 2004, we needed to install casing around the windows when we had the drywall replaced. Before, we had drywall wrap without any casing. I actually liked the clean look of the drywall wrap much better than the typical framed window with casing, but the casing that the trim carpenter did was fairly minimal and matches the window's wood nicely:

Here you can see a shot down the house from the upstairs hall. The colors are really nice too, much better than the old dark pink/orange. The Lovely Wife picked out the colors, and did a fantastic job. They are much more interesting than the old color scheme, and the house seems much brighter. Here's the stairway through the living room door:

As you can see, the carpet is now on upstairs and on the stairs.

Larry and Carlos have also been busy on the urbanite. After it stopped raining yesterday afternoon, they came and worked, then Larry came back this morning. Here's what the pattern looks like:

Larry says that they mostly do irregular patterns with urbanite because the concrete is too broken up to really make a regular pattern from. But, here again, The Lovely Wife stepped in when the concrete guys came to break up the concrete and had them cut it into regular chunks. So we get a nice, clean regular pattern. TLW also bought some recycled, milled glass for filling in on top of the base rock between the slabs. Should be interesting. I suspect at some point we'll probably do the entire walkway into the back yard, and maybe the driveway too.

The floor protection was supposed to come off on Fri., but nobody showed up. I guess they figured what is another day in a 9 month job? But somebody, probably Christine, redid the dust protection on the kitchen and sun room. I suspect the drywall dust will start flying about when the pull up the floor protection. This week the floor guys are supposed to sand and refinish the floor, and then the trim work needs to get done. The schedule says that they will be complete on Apr. 5 for the city inspection, but I expect there will be at least a week or two's worth of work on punch list items after that.

I also spent some time today trying to fix the water features in the garden, for the garden show in 3 weeks. We have 4 solar fountains, and only one of them works at the moment. There was not enough sun for me to properly test the large fountain, so I put the pump back into the box for another day. The bowl fountain out front was easy to fix. The pump had its own solar panel, and I only needed to plug them together. The sun came out a couple times and it seems to be working well, water was squirting up from the nozzle. That leaves the barrel pond in the back. The pump is dead, these cheap Chinese DC pumps don't last very long. But I don't have any replacement. I thought TLW had purchased one, but that was the pump for the bowl fountain. So I'll need to get one.

Measuring Insulation Effectiveness

2011-03-21T20:38:00.000-07:00

An important reason for doing this blog is to measure the effectiveness of various green technologies and report on the results so other people have some idea about what works and what doesn't. In general, measuring CO2 emissions directly is difficult. I've been primarily measuring effectiveness by deploying a green technology, like a solar PV system, then measuring what my energy use is with the technology in place and calculating from that what amount of CO2 was saved. I've done this by taking the CO2 intensity (in kg. of CO2 per energy measure, for example kg. per kilowatt-hours or therms) and multiplying it by the amount of energy not used in the previous time period, say a year. It would be much easier if I could simply measure the amount of CO2 my lifestyle is emitting now and then measure again after the green technology is deployed, but that isn't possible. For some energy sources, like gas or gasoline, this could be done, but for others, like electricity, the CO2 emissions are some distance away and I could not get the measurement without some intermediary, like PG&E, reporting it to me.

Although it is not possible to directly measure the CO2 emissions reduction from the closed-cell foam reinsulating job we did, it is possible to see how effective the insulation is in reducing heat loss from the house without waiting a year to see how much less gas we use. There are a couple of ways this can be done. One simple way is to take a look at the roof on a cold winter morning when there is frost on it, and look for places where there are bare spots or areas where the frost is less thick. Bare or thin spots are an indication that heat is leaking out of the house through the insulation preventing frost from forming. A uniform frost coat indicates that no heat is leaking through the roof.

I don't have any pictures of the roof prior to the reinsulation, but I did check it out last year on a few cold January days. There were plenty of bare spots, and the frost coat itself wasn't very thick. That was an indication that the insulation was poor. Below you can see a picture I took in the middle of February, this year after the insulation job was done, when we had a few nights with temperatures in the 20F's:

As you can see, the frost coat is interrupted by vertical lines that run up and down the roof. While it is difficult to see on this blurry photo, some of the lines are much thicker than the others. But even the lines have some frost on them, unlike the situation before where there were bare patches all over the roof with no frost.

These lines are an example of thermal bridging. I've discussed thermal bridging before in this blog: here, here, and here. After much agonizing, I decided not to try to address thermal bridging for the whole house in our system remodel because it would have been expensive and the contractor who is doing our work would be likely to screw it up. I did decide to do some thermal bridging work on the back wall where we found mold on a stud face, using Thermablok. I wanted to reduce the possibility that warm air would condense moisture on the stud face and cause mold to form again. In fact, Paul, our contractor, did screw it up. He had the drywall installers apply the Thermablok tape without supervising it himself, and they ended up having to redo the job because they put a single 2" wide tape strip in the middle of the stud face when the stud was wider that 2" instead of applying multiple 2" wide strips to the entire stud face.

The thermal bridging you can see in the photo above comes from the beams in the ceiling, which act as heat conductors from inside to outside of the house. The beams are at around R-5 while the bays between them are now at R-30. The bays are clearly covered in a thick layer of frost. The beam areas have a thinner layer. Some of the beam areas are larger because we had large rafters installed to stabilize the roof ridge, which was shifting and causing the drywall to crack.

Another way to measure effectiveness is through thermal imaging. If you recall in this post, I discussed the thermal imaging test we had done in 2008. We had another thermal imaging test done in February after the closed cell foam was installed. Unfortunately, the thermal imaging test sat at the testing office for three weeks until the drywall installers were almost done with hanging the drywall because our contractors were convinced there were no problems and I was simply too busy to track the results down. Fortunately, there are very few problem areas, and, as we'll see below, the major ones may be addressable from outside.

In most cases, the areas that showed up as problems in the 2008 imaging test (like above the fireplace or in the east family room wall near the outside door) had no issues this time, and there were some areas now that are new. One interesting comparison, though, is of the master bedroom west wall. Here's a picture from 2008:

And here is the picture from the thermal imaging test done in Feburary after the new closed-cell foam insulation was installed:

The blue stripe down the middle in the top picture shows cold air leaking into the master bedroom through the back wall in 2008. In the bottom picture, the cold stripe has disappeared in 2011. The interesting thing is we did not do any reinsulation in the master bedroom. The original report noted that the cold air leak was probably due to insulation that had pulled away from the stud, but we had that wall redone in 2006 when we had the master bedroom remodelled, so unless the contractor was completely incompetent (not an impossibility but probably not the case here), it is hard to see how the insulation could have slumped in that short a time.

Here is a picture of the east wall of the master bedroom from 2008, part of which is also captured on the left side of the picture from 2011 above:

You can see here cold air leaking in through the headers and down the stud at the junction between the two walls. All that has disappeared in the 2011 photo.

I suspect this improvement is due to the work that we did on the upstairs bedroom immediately above the master bedroom. We had the upstairs bedroom reinsulated with closed cell foam and we also had the ceiling of the small "attic", where the HRV is now located, immediately above the master bedroom reinsulated. What was probably happening was that cold air was leaking in through those areas, where the fiberglass batt was more than 30 years old and therefore in much worse condition than the batt insulation in the master bedroom, which was installed only 4 years ago. Since cold air is heavier than warm air, it likely flowed down through the fiberglass batt and along the studs. Fiberglass batt is not airtight, like closed cell foam.

One thing that hasn't changed is the front door, but that is not surprising because we had no work done on it. Here's a picture from 2008 of the threshold:

Here's a picture from 2011 of the same area:

Our front door has a metal threshold that acts as a heat conductor to the outside. Paul will replace this by a wood threshold (or at least we hope he will) near the end of the job when various finishing work is done.

Another problem area on the door is the upper left corner and left side. Here's a picture from 2008:

Here are two pictures showing the same area from 2011:

Again, the cold air leak is pretty obvious, though the area above the door shows less leakage because it is now much tighter.

There are a couple of spots in the family room where there appears to be air leaks that cause the studs to become significantly colder than simply from thermal bridging. Maybe air is leaking down along the studs somehow, despite the sealing that the closed cell foam is supposed to give. Here's the upper corner near the kitchen, on the west wall (and below that, the visible light picture):

This is a fairly complicated corner, and the kitchen area, behind the plastic, was not reinsulated so it is not surprising that there may be issues. I suspect an air leak coming from the outside, where there is some flashing loose above the small attached shed:

When the current circus has loaded up and left town, I'll get out my small spray foam can, spray the hole shut, and nail up a piece of flashing to close it off to the weather.

The back family room corner has a similar problem:

This is a cold spot along the beam at the bottom corner. I'm wondering if that could be from the missing piece of trim wood along the upper part of the house:

Of course, one would expect that the cold spot would show up at the top, but maybe the cold air is running down along the stud until it finds a place where there is some weakness in the insulation, or maybe it just pools on the outside of the house and cools down the stud. Paul thinks is may be from gaps in the footers, since in 1976 when this house was built they made no attempt to seal off the footers. In any case, I'm going to try sealing this one up from outside too, both at the top and bottom.

There are a few other spots where there is cold air coming in along a stud. One of the worst is in the living room, on the north wall. Here you can see three pictures where the cold air comes in along the corner and the through the footer. This one is on the upper corner:

This one is right below the above picture:

And here is along the footer:

The corner looks like below in visible light:

Again, it is a complicated corner. These may also be addressable from outside, perhaps spraying foam up into the crack between the siding and the footer, or something like that. And there may also be some kind of hole or something. The electrician did install a small FM radio antenna and left the hole uncaulked, but I doubt that hole was enough (I caulked it shut anyway but after the thermal imaging test was done).
The other leaks are in the upstairs bathroom and bedrooms. The bathroom has a leak right in the center of the outside wall through the studs:

The studs here are kind of complicated, so it does not surprise me that they may have missed it. On the other hand, it might be the old forced air duct in the middle of the picture. Maybe it is bridging to the outside. Here is a visible light picture of the same area:

We probably could have addressed this if I had received the thermal imaging before they started installing the drywall, but now of course it is too late.

There is also one on the ceiling in Bedroom1:

And the dormer corner on Bedroom2:

As well as two others, one in Bedroom3 and Bedroom2. These are probably impossible to address now, since they involve the roof.

Overall, the thermal leaks we found were not all that serious, with the exception of the ones in the living room and the ones in the family room, which may be addressable from outside. I can't say I'm happy that we didn't get the opportunity to do this right, but I'm not prepared to rip out the drywall again. At this point, after living 9 months in the back bedroom and kitchen and 4 months of rain and cold walking between them, I'm eager to get back in my house.

Progress on Urbanite and Siding

2011-03-20T21:12:00.000-07:00

I returned home from a business trip on Fri. to discover progress. The solar PV system install was done, PG&E sent our permission to turn it on, and the siding work looked mostly done. The siding under the living windows had been replaced:

The rat screens were supposed to have been taken off, since the original siding overlapped them. But I'm not too particular, they can stay on as far as I am concerned.

They also replaced the siding on the back of the house where Our Good Friend Duke went wild with ventilation hoods:

Unfortunately, they were a bit too abstemious. I wanted a ventilation hole for the HRV attic, to avoid allowing mold to develop from condensation, as occurred before. They'll have to cut one, as far away from the HRV intake vent as possible.

They also replaced the siding where the old electric breaker box and meter were embedded in the garage wall:

And finally, on Saturday, Larry and Carlos came and started filling the hole where the sidewalk was torn up for the electric upgrade with urbanite:

Right now, they've just laid the pieces down so that we can attest to her satisfaction with the pattern. They will level them and lay gravel between the pieces later.

New Solar PV System Underway

2011-03-12T12:13:00.000-08:00

REC started installing the new solar PV system this week. The Fronius inverter is considerably larger than our old SunnyBoy:

Below the inverter is a hole in the garage wall where the Tigo power monitoring cable leads to the controller inside the garage (sorry a bit blurry):

The Tigo controller itself is mounted on the inside garage wall:

I was a little concerned that our garage shelves wouldn't fit flush with the wall, but Lauren at REC said that the crew had measured the distance and it should be OK. This kind of attention to detail is what distinguishes professionals like REC from amateurs like our good friend Duke, who installed our HRV system.

On Thurs, REC had the mounting rails up on both sides of the house (and probably on the dormer too but that's hard to see). Here you can see the rails on the west side, where the old system was. Note the rope the crew uses for tying in, very smart on our steep roof:

You can see the power conduit leading down to the inverter.

Here's the rails on the east side:

The next day, they had the panels installed on the east side:

and on the dormer:

You can just see the edges of the panels on the roof of the dormer.

Here you can see the Tigo modules on the back of the panels still in the garage:

These communicate with the controller in the garage to maximize the energy output of the PV system.

There are 16 panels in the garage yet to mount on the west side. Then we have to wait about a week until PG&E certifies the system, but fortunately our meter doesn't need to be swapped out. Lauren sent email and said that REC would be finishing the job on Tuesday, since Monday is their Employee Appreciation Day. What a concept! Somebody ought to tell Scott Walker, governor of Wisconsin, about that.

Refining Residence Time Comparison

2011-03-11T21:20:00.000-08:00

I've been thinking about how to more accurately compare the Global Warming Impact (GWI) of the HFC released during our closed cell foam insulation job against the amount of carbon that I estimate will be saved from the insulation. My original estimate, in this post, was that it would take 214 years before the estimated amount of carbon saved would equal the CO2 equivalent of the HFC emitted by the insulation job, since HFC has about 1000x the GWI power of carbon dioxide comparing by weight. But that calculation didn't take into account the residence time. The residence time of HFC in the atmosphere is just 10 years while that for carbon dioxide is around 500. Because it hangs around in the atmosphere 50 times longer than HFC, carbon dioxide causes a much larger impact over time. In this post, using a fairly simple measure that incorporated residence time, I calculated that the carbon payback time would be around 4.3 years. That calculation seemed too simplistic to me, so I decided to try to develop a mathematical model of the GWI for both HFC and carbon dioxide. In this post, I'll explain the model and why I think it is the right way to think about comparative GWI for HFC and carbon dioxide. I'll try to keep the math simple, but there will be some as it is unavoidable given the topic. If you suffer from a math allergy, I'd suggest skipping to the end of this post, where a couple of graphs give a nice pictorial representation of the model.

First, let's review the basic facts about the comparison. The HFC from our insulation job resulted in the release of around 128 metric tons of CO2 equivalent (CO2e) HFC. Now, in actual fact, only part of that was released immediately. Some will leak out over time as the foam ages, some will remain trapped in the foam and only be released when the house is demolished. But for purposes of comparison (and buying carbon offsets, which is the important point) we can assume that the insulation job resulted in an instantaneous release of 128 metric tons of CO2e when the foam was installed, because we have even a less precise model of how these other processes work than for an instantaneous release. I've estimated that the insulation will decrease heating gas consumption in the winter around 30%, which will result in saving around 0.5 metric tons of CO2 per year. So these are the two numbers we have to work with: 128 metric tons of CO2e released in a single pulse this year and 0.5 metric tons per year of CO2 saved as long as the house stands and we use gas heat.

Both CO2 and HFC decay in the atmosphere over time. Taking the case of HFC, we have a pulse of the compound emitted at the beginning of the time period, then after that, the rate the concentration decreases depends on the rate that is still there. By year 10, the concentration will be zero. We can model this with a rate equation like the following

Where R(t) on the left indicates the rate at which the concentration changes at year t, C(t) on the right indicates the concentration at year t, and 1/N is the time constant of the decay, with N being the year at which the concentration reaches zero (10 in the case of HFC).

Now this equation doesn't give the actual concentration of C, it just gives the rate at which it decays. But as it turns out, this equation can be analyzed and turned into an equation in t and C which will let us calcuate, for any year between 0 and N, what the concentration of C is. The procedure is well known and many natural processes exhibit the same general form. It's called exponential decay.

While this equation works for the case of the HFC emission because we're assuming all the gas is emitted at once, it won't work for the CO2 we save from not having to heat the house. That is released over time. In fact, as mentioned above, 0.5 metric tons are released every year. We need a new rate equation, one that takes the difference between the rate at which the CO2 is being released and the rate at which it is decaying. Because the rate at which it decays is small (500 years is a long time, after all), the contribution of the decay is not big until the house stops being heated, which amounts to the time at which the house is torn down. The rate equation in this case is:

A here is the amount that is emitted every year and 1/N * C(t) is the rate at which the amount that is there is decaying. Note that the equation is only valid up until the year T in which the house is torn down, then the first equation becomes valid, because the house isn't emitting any more CO2, but the amount that was emitted still needs to decay. It will take 500 + T years for all of it to be gone from the atmosphere. This equation isn't as easy to analyze as the above one, but with the help of a computer it is possible to numerically calculate a series of numbers giving the estimated concentrations.

Enough math. The following graph compares the concentration path for three different cases: the HFC, CO2 from heating if the house stands for 30 years, and CO2 from heating if it stands for just 6 years:

The blue shows the HFC concentration, the red shows the CO2 concentration if the house continues to emit CO2 for 30 years and the green shows the concentration if the house emits CO2 for 6 years. The graph runs out to 530 years (sorry, Excel won't put any numbers on the far end).

Just looking at this graph, the emissions from the house even if they last 30 years don't look so bad. Sure, they go on for a long time, but they never get as large as the HFC. However, if you instead look at the cumulative effect over time, estimated by adding up the amount of carbon in the atmosphere every year until the concentration goes to zero, the emissions from the HFC look fairly harmless in comparison to the house:

This graph shows the cumulative GHI for 5 different scenerios: the three shown above, plus two cases where the house stands for 4 years or 5 years. The GHI impact of the HFC effectively ends in year 10, while that for the 4 heating scenerios goes on for up to 530 years. If the house is assumed to stand for 30 years, then the cumulative GHI is more than 6 times that of the HFC release scenerio!

This graph is, to me, truly frightening. Turning my thermostat up essentially contributes incrementally to modifying the climate 400 years from now. The graph also tells me that, despite the GHG emissions from HFC, putting closed cell foam into the house was the right decision, from an environmental standpoint.

The three cases where the house is assumed to stand for 4, 5, and 6 years help figure out what the carbon payback time is, taking residence time into account. For 4 and 5 years, the cumulative GHI is less than that of the HFC, while for 6 years it is slightly greater. This says that a cumulative GHI of 6 years is about right for figuring out carbon offsets. After 6 years, the total amount of CO2 emitted is 3 metric tons. The carbon offsets, at $10 per metric ton, would therefore be $30.

Nissan Leaf Free Electric Car Charger and Privacy

2011-03-03T20:32:00.000-08:00

After you've ordered your Nissan Leaf, Nissan insists you schedule someone to come by and assess your electrical system and garage for charger installation. I originally contacted Aerovironment, the charger company Nissan is working with, in December about buying a charger but was told I had to wait. Sometime in early January, I received an email from Nissan to sign up for a charger assessment, so I scheduled an appointment as late as possible in February because I wanted PG&E to finish the 200 amp upgrade and the electrician to complete installing the 240V/40 amp circuit for the charger. My assessment was Monday this week. Unfortunately, due to a snow storm on Fri. last week, PG&E couldn't complete the 200 amp service installation until Wed. this week, though the electrician did get the 240V circuit installed. I was a little anxious whether the assessor would pass my house given that the 200 amp service was still a work in progress.

The guy from Aerovironment came on Monday about 5 minutes before his scheduled timeslot was due to expire. He took some pictures of my house number, electrical meter, and the junction box in the garage where the charger would go, then pasted up a picture of the charger next to the junction box. I guess the picture is to guide the installation guys about where to install the charger. He said he would email me a quote, but wouldn't tell me what it was. But he did say that the electrical work we were having done was fine and he was quite relieved that he didn't have to pull a permit for it nor have any additional upgrade work done. Installing the charger itself doesn't require a permit.

In addition to the Aerovironment charger, some time ago I also signed up at the EVProject for email about progress. The EVProject is giving free chargers to electric car customers for the right to collect data on their electric car usage. Now, normally I am a real stickler for privacy. I don't use my CVS discount card nor grocery store discount cards because you are in effect trading information on your purchases for the discount. Perhaps I wouldn't be so picky if I really needed the discount, but I don't see in principle why some company should get this kind of information so they can spam me with paper junk mail and otherwise target their marketing at me.

However, the chargers being offered by the EVProject looked like a much better deal. First off, it's a lot more money, something like $2K. Compare that to a couple of cents off a box of tissues at CVS. Secondly, the most potentially sensitive information they are collecting - where the car is located - is known to my cell phone company anyway. ATT always knows exactly where I am because the active cell phone in my pocket is telling them. Since the same privacy constraints bind ATT and the EVProject (at least according to the agreement with the EVProject), I don't have much worry that they'll use the information for some tawdry commercial purpose. In fact, what I think they are collecting the information for is to decide where to install public chargers. So, in the end, not only do I get a free charger but also the information will help improve the infrastructure for electric cars. Finally, I actually get to view the information, so I can track my electricity usage and other data on the car.

For some unknown reason, the San Francisco Bay Area was one of the last areas to be approved for EVProject enrollment. A few weeks ago, I received an email from ECOtality, the car charger company that is managing the EVProject for the U.S. government: they were now taking applications in the Bay Area. I called Nissan to find out what to do, and they said I should just log into my Nissan Leaf account and apply for participation in the program. So I did. The application involved filling out a form with information about my electrical system, what appliances I have, and whether I had a WiFi access point through which the data could be uploaded to the Internet. On Monday night, I received an email from ECOtality with the happy news that we had been accepted into the program. I never did see the Aerovironment quote, but I'm not concerned.

The ECOtality charger is a bit larger than the Aerovironment charger, and it has a reel for rolling in the cord. After three years of dealing with the cord on our plug-in Prius conversion, I don't feel the need for a reel but possibly it will come in handy. The ECOtality charger also has an LCD screen on it, about which I have some mixed feelings. Generally, I think it would have been better to simply allow people to log in over the Internet or through their smartphone to view this kind of data. Software apps are cheap while hardware is expensive. But, hey, the charger is free as long as I am in the program and I get to keep it when the program completes, so I am not complaining. And I am really happy that it collects data on the electricity usage of the car, as this is something I wanted to do by myself. The basic Aerovironment charger has no connection to the Internet.

In addition to the free charger, ECOtality also supplies a free 440V DC charger for the Leaf. The 440V DC charger allows the Leaf to fast charge in around 20 minutes, something the Chevy Volt can't do. ECOtality sells a commercial charger with a 440V port on it, but I suspect the EVProject is also interested in collecting data about how often people travel beyond the 100 mi. single charge range of the Leaf by quick charging using the 440V charger. At this point, I am just getting started with EVs, so I don't have much idea about whether we'll try to do longer trips. I do know that the Leaf's built-in public charging spot map often directs you to a charger with an older plug, that was used for the original EV1 in the 1990's, so it might not be all that reliable yet if you want to make a longer trip. Eventually, these older chargers will be replaced of course. It will be interesting to see how the public charging infrastructure develops and to play an active part in contributing to weaning the world off of fossil fuels by the data the EVProject collects on our Leaf.

The Conduit is In

2011-02-25T20:24:00.000-08:00

On Wednesday, I came home at noon to the happy sight of a PG&E crew hard at work...having lunch. But they earned it:

The trench shows where the conduit will be laid. When I got back home at night, the trench had been filled in, up to the new breaker box. But PG&E had taken two of the four boards we have laid over the muddy area where we had to take out the sidewalk. :-(

They came with some pretty impressive equipment:

Fortunately, despite the day-glo markings in the street, they didn't put their John Deere to work on it, so no trenching in the street. I wonder if the will come and remove that legal graffiti or if we'll have to live with it until it wears off?

Update 3/3/2011: It snowed in the mountains last week, so PG&E couldn't come and pull the cable last week, but they did show up on Wed. this week and we now have 200 amp service. The breakers for the new circuits aren't in yet, though, but that should happen next week.

The Sun

2011-02-25T20:14:00.000-08:00

Periodically over the last few months, I've been checking the temperature on the solar hot water tank. It hasn't been over 80 degrees since the beginning of December. When I checked last weekend, it was 84. Here's why:

This picture was taken around noon last Wed. looking south from the west side of the house. The sun is over the redwood trees now, which means the solar thermal collector on the northeast side of the roof is getting more than 4 hours of sun a day.

Spring is on its way.

Little Flags

2011-02-21T19:29:00.000-08:00

I went out front this morning and saw that PG&E had put in a bunch of little fluorescent flags and sprayed around some fluorescent paint:

It looks kind of festive, but the point is to show the guys digging the trench where the gas, electrical, and cable TV conduits are underground. There are some markings in the street too. I wonder what those are for, theoretically, they shouldn't have to dig the street up. Hmm.

Now, if the guys digging the trench had an augmented reality app for their iPhones that let them point the iPhone at the conduit box and it would provide a picture of what was underground, they wouldn't have to send out a crew to stick in the little flags and spray up the street and ground with officially sanctioned graffiti. Sounds like a business!

Anyway, these are signs of progress. With the drywall guys whaling away at the inside and PG&E spraying fluorescent paint and sticking flags in everywhere, I'm starting to get a little confidence that we just might have everything wrapped up by the end of March, which is what the current schedule says.

How to Account for Residence Time?

2011-02-19T21:19:00.000-08:00

If you recall from my last post, I estimated a carbon payback time for our closed cell foam insulation at around 214 years, based on an estimate of 120.38 kg (0.12038 metric tons) HFC emitted and an estimated savings of 0.562 metric tons (mt) of carbon per year (30% reduction in annual natural gas use). The calculation assumes that HFC245fa has an instantaneous global warming impact (GWI) of 1000x carbon dioxide.

There is one problem with this way of measuring the impact HFC245fa relative to CO2. It does not take into account that the residence time of HFC245fa in the atmosphere is around 7-10 years while that of carbon dioxide is around 450-500 years, and when the HFC breaks down, there are no long lasting products remaining. So this means a kilogram of HFC245fa put into the atmosphere now will cause 1000x the global warming of a kilogram of carbon dioxide for 10 years, but then it will be gone. A kilogram of carbon dioxide, on the other hand, will continue to warm the planet for another 490 years before it disappears. Simply comparing the two gases based on their instantaneous GWI therefore doesn't seem quite right.

This is a problem system engineers face all the time: how to calculate a number that lets you compare the impact of two different technologies/treatments/etc. on a system. The number is called a figure of merit. In effect, it lets you compare apples and oranges along some common metric, like for example the percent energy in the pure red color light (at 700–635 nm wavelength) reflected by their skins, of value in judging their relative contribution to solving some problem. In our case, we want a formula to calculate the weight of carbon dioxide equivalent (CO2e) for the HFC that takes into account both the instantaneous GWI relative to CO2 and the residence time relative to CO2.

My previous post calculated the CO2e for the HFC like this:

       wt. CO2e = wt. HFC * instantaneous GWI

But, as mentioned, this doesn't account for the residence time.

So we need to adjust the right hand side so that the reduced residence time for HFC over the equivalent amount of CO2 is accounted for. This means that we need to multiply the instantaneous GWI by a number that will decrease when the residence time of the gas for which the GWI is desired decreases relative to CO2 (or correspondingly increases if the gas has a longer residence time). One way to do that is to divide the residence time of the gas by the residence time of CO2 and multiply the instantaenous GWI by that to obtain a time adjusted GWI:

       time adjusted GWI = instantaneous GWI * (residence time of HFC / residence time of CO2)

If the residence time of the HFC increases relative to CO2, the factor on the right side will increase, causing the time adjusted GWI to increase, and vice versa, which is what we want.

Now we can use the time adjusted GWI for the CO2e calculation:

      wt. CO2e = wt. HFC * time adjusted GWI

In the case of HRC235fa, we have:

     instantaneous GWI      = 1000
     residence time of HFC = 10
     residence time of CO2 = 500
     time adjusted GWI       = 1000 * (10 / 500) = 1000 * 0.02 = 20

Plugging the time adjusted GWI into the equation for CO2e for our case gives:

      CO2e = 0.12038 mt * 20 = 2.4076 mt

At 0.562 mt of carbon eliminated per year, this gives a payback time of:

    payback time = 2.4076 mt CO2e / 0.562 mt CO2 per year = 4.284 years (!)

This is considerably better than the previous figure of 214 years. The carbon offsets for 2.4076 mt CO2 come to only $24 rather than $1203.80 as calculated in the previous post.

People who are not used to making engineering tradeoffs look at this kind of calculation and scratch their heads. Which number is right? Are we just playing with numbers or is there some kernel of truth in all this arithmetic? I suppose you will have to answer that question for yourself. But if we are ever to come up with sustainable technical solutions to the systems in our society upon which we depend, we are going to have to come up with ways that fairly and accurately compare different kinds of solutions that have differing impact. Having a single number that summarizes this impact, like the time adjusted GWI, makes such comparisons a lot easier.

Update on GHG Impact of Closed Cell Foam

2011-02-14T21:08:00.000-08:00

If you recall from this post, I estimated how much CO2 equivalent green house gas (GHG) would be released during the closed cell foam insulation of our house. I made a math error. At 11.7 lbs/therm and 106 therm/yr eliminated by the insulation (figuring at 30% of the heating carbon), that's 1240 lbs per year of CO2, not 2907 lbs as I said in the post. So the estimated carbon footprint payback time would be more like 145 years and not 80. Gulp!

Well, I now have exact figures, this time in metric, where it is easier to spot errors. Ponzini used 0.76 cubic meters of the B component, of which maximum 12% is HFC-245fa, or 0.0912 cubic meters. The density of HFC-245fa is 1320 kg/m**3, so the weight of HFC-245fa emitted is 120.38 kg. Since HFC-245fa is about 1000x as potent a GHG as CO2, that would be 120,380 kg CO2 equivalent, or 120.38 metric tons. Assuming again a 30% reduction in heating gas use due to the insulation, 1240 lbs of CO2 eliminated is around 0.562 metric tons, so it would take 214 years for carbon footprint payback. Double gulp!

Note that the 30% reduction in heating gas is just an estimate. It is based on a spreadsheet model of our house that I made a few years ago, which didn't take the floor into account, and probably has other errors. So it's possible that we might get better performance, or even maybe worse if I overestimated somewhere. We will see in the coming years.

A carbon footprint payback time of 214 years sounds like a long time, but fortunately, there's carbon offsets. You can buy tax deductible carbon offsets at Carbonfund.org at $10 per metric ton. They have a variety of programs in the categories of renewable energy, efficiency, and sequestration. I like the forestry projects because, in theory, they can be long-lasting, 80-100 years. Here's a link to one, the Nez P erce Reforestration Project in Idaho. Though HFCs stay in the atmosphere a much shorter time than CO2, as discussed in the previous post, the foam will outgas for a while until it stabilizes, and I would like my credits to last as long as the house or even longer. So I am on the hook for a donation to Carbonfund.org of ~~$120.38~~ $1203.80.

Now, you might ask, since carbon offsets are so cheap and the insulation was so expensive, why not simply buy carbon offsets. Actually we do that already for the gas we use for heating, and there were other reasons for using closed cell foam in this house, as discussed in the last post. But there is no guarantee that the next owner of the house will be so diligent. With the foam in place, the house should be good for another 30-100 years, long after I'm gone. And it will continue to save carbon.

Clarification on the Electrical Service Upgrade

2011-02-13T14:40:00.000-08:00

The Lovely Wife brought up an issue with my last post. She asked why if our intent to save energy we were getting a much bigger breaker box. Also, I thought I would clarify a bit how our underground electrical service works. Most houses in the US have their service from wires strung in the air from the power pole to the house.

The reason we have a bigger breaker box is because we are getting at least 4 new circuits in the breaker box which will serve the house. These are three 220V/20 amp circuits for the on demand electric hot water heater, and one 220V/40 amp circuit for the electric car charger. There may be a couple of additional 110V/15 amp circuits for the HRVs and the garage. All our existing electrical circuits will remain unchanged on the existing inside house circuit breaker panel, which has no space for the new circuits. The old panel on the outside of the house, which you saw in the photo on my last post, is much smaller because it contains only one breaker in it, a 100 amp breaker for the whole house. The new one will contain the 200 amp breaker for the whole house, plus the breakers for the new inside circuits.

As for saving energy, our system remodel is designed to save on heating gas through much more effective insulation. When it comes to electricity, though, we are substituting electricity for other sources of energy that are harder to make renewable. The on demand hot water heater will substitute electricity for gas for backup hot water heating (the main hot water heating is solar), and the electric car charger will substitute electricity for petroleum-based gasoline. Then an expansion of our solar PV system will offset all but 2000 kwh/yr of our electricity use with clean, 100% non-fossil carbon based solar electricity. The 2000 kwh/yr (estimated) that we do not offset will be drawn from the grid. Since the State of California has a renewable mandate of 20% by 2020 (with 33% being a stretch goal), the likelihood is that the grid will become much cleaner before transportation fuels or heating gas do (btw: don't let the media story of "clean" natural gas fool you, natural gas produces fossil carbon and thus contributes to global warming too, it just produces much less of it, about half that of coal or oil).

Because our service is underground, the upgrade process has been very complicated. Most people in the US (and many other parts of the world too) have service from an aerial line that runs from the poles on the street where the utility has their lines to the house. Upgrading such an aerial line is much simpler, the lineman comes, removes the old line, installs a thicker new line, and you are done. Of course, you still need to get a new breaker box with a larger breaker for the 200 amp service.

In our case, the utility lines are buried in conduits beneath the streets, along with the phone lines and the cable lines. This makes our neighborhood look much neater, without a lot of poles along the streets with wires draped over them. But it does make upgrading the service much more difficult. Here is a picture of the cement box where the electrical lines enter my and my neighbor's property:

Somewhere beneath that box, two conduits lead out at angles to our houses. My neighbor had his service upgraded to 200 amps in 1985 when he had central air conditioning installed.

When PG&E comes, hopefully on Feb. 23, they will dig a trench from the box to the place where the pipe from the new breaker box is, under the area where our sidewalk used to be (and will be once again when the job is through). Here you can see a clear space to the concrete access box, which is right next to the green sword shaped leaves in the center of the picture (it's a naked lady, native California plant that blooms in August):

There are still a couple of clearing items that need to be done, the small rock wall, and I think we will probably have to repair the irrigation in our neighbor's yard if the trenching damages it. But I think PG&E shouldn't otherwise have a problem with digging the trench.

Progress on Drywall and Electrical Box

2011-02-12T20:24:00.000-08:00

We now have a firm date from PG&E when they will come and start installing our 200 amp service. Trenching should occur on Feb. 23, when they will install the conduit and backfill. On Feb. 25, they will pull the new cable, connect it to the grid, and transfer the meter. In preparation, we now have a new breaker box on the side of the garage:

This box is considerably larger than our existing breaker box:

I think we are going to need to paint the new one or something so that it isn't as visible.

Today we had the gardener come an clear out all the vegetation between the concrete box on the border between our property and our neighbor's, where the underground electrical service for both our houses comes in. We were warned by PG&E that we had to have all the vegetation out in a straight line between the breaker box and the concrete box or they would not dig the trench.

The drywall guys started this week in earnest. Paul convinced them to install the Thermablok on the south hallway wall studs, but, as you can see from the following picture, they didn't quite get the concept:

On this wall, there are a couple structural members that consist of two 2x4 studs right next to each other, like the one in the middle of the picture. Rather than gluing two pieces of Thermablok on the studs, they glued one on going up the center. I guess they thought it was a standoff for the drywall or something. Anyway, we had them rip out the drywall that they had installed and redo it. Unfortunately, I didn't have time to check afterward whether they did it right the second time or not, so I don't know if they got it in. Paul called the owner and I put a message in Spanglish on the wall as to what they should do. The drywall is now up:

There are a couple places in the house where the studs have bent or warped a bit with age. Here you can see that on the top right next to the steel strap:

These areas are going to require some planing to make them more even so that the drywall doesn't protrude. We have decided on a smooth texture to our drywall, so there is no room for hiding imperfections in the surface.

There are also some problems around the windows. We had the windows replaced in 2004 from the outside. Here you can see how they used nails to shim the window:

In other places, the caulking bead goes from an eighth inch on the top to a quarter inch on the bottom. Previously, we had a nice contemporary finish where the drywall wrapped into the windows and there was no molding. Now, we will need some kind of wood trim to hide the imperfections. We're planning on using a stained wood, which matches the wood in the downstairs windows.

New Concrete or Urbanite?

2011-02-06T18:41:00.000-08:00

PG&E has finally begun to respond, and we now have a date of Feb. 28 for the start of the 200 amp upgrade. We began the process in late October, and in November were given a start date of December 24. December 24 came and went, and in early January they began asking the same questions that they were asking us in early November when we started the process, suggesting that someone had forgotten about our application. The Lovely Wife sent a irritated note to the woman in charge and someone else, who forwarded it to the manager. Now, things seem to be moving along, if still somewhat slowly. We would like to get an earlier start date, since Aerovironment is supposed to come on Feb. 28 to do a site assessment for the electric car charger. The 240V/40 amp circuit needs to be in place and hot by the time Aerovironment shows up. In any case, sometime in the next month we expect PG&E to have the service at least started.

This week, we began the process by having the concrete removed on the area around the gas and electric meter, where our underground service enters the house, as you can see below:

Because we have underground service, it is not simply a matter of stringing a new wire. We need to have a trench dug, the conduit removed and replaced with a larger one containing a larger cable. However, there are complications. Since our house was built, the code has changed and now they will not put a breaker panel directly next to a gas meter where the current one is, probably due to the possibility that a spark from the breaker could ignite a leaking meter, especially during an earthquake. So they need to move the new breaker panel around 4 feet down the side of the garage, on the other side of the gate to the back yard. The electrician is coming this week to put in the new breaker panel. He will wire in all the new circuits, including the three 220V/20 amp circuits for the electric on-demand hot water heater, the circuit for the car charger, and probably a couple of 110V/15 amp circuits, like the new one in the garage where the plug-in converted Prius will be plugged in. That leaves only connecting up the new breaker panel to the main and into the old main panel, which will become a subpanel, for the service upgrade to be complete.

We also want to reroute the rain gutters on the west side of the house so that we do not have two downspouts emptying onto the sidewalk on the west side. They leave a mess there every winter: leaves from our neighbor's Polycarpus trees, gravel from the roof, a wet spot that doesn't go away because the area doesn't get any sun at all, and, to top it all off, green moss that makes the sidewalk slippery. The new design will drain around 2/3 of the roof on that side forward and down a spout on the front next to where the concrete is currently out rather than through two spouts onto the sidewalk. The water will drain out into a narrow strip garden between the driveway and the neighbor's property. The garden will need to be replaced, because it is exactly there that PG&E will be digging the trench.

The removal of the concrete left open the question: what to do about the hole? Our original plan was to simply lift one section of the sidewalk off or have PG&E tunnel under it rather than remove it, but the need to move the breaker panel impacted more of the sidewalk than we had originally anticipated so it had to be removed. To handle the new roof drainage, we had planned to slip a pipe under the sidewalk for the downspout drain. Now, we have to replace a larger section of the sidewalk. We could of course have fresh concrete poured, but cement production has one of the highest green house gas production rates of any product, so avoiding new concrete seemed like a good idea.

Besides, the old concrete is still in good condition. These days, they don't take a jackhammer to concrete when they want to break it up, but use a saw to cut it very precisely. Unlike the concrete in our backyard that we had removed a few years ago to enlarge the garden, this sidewalk didn't have any rebar embedded in it so it was fairly easy to remove and came out in regular pieces as you can see in the following photo:

The pieces look like the concrete pavers we saw at Lyngso Garden Supply last week, just bit thicker and denser. In fact, they look as if they should work quite fine as urbanite, the sort of fancy name people in the green garden trade give to concrete that has been removed, broken up, in some cases dyed, and reset as pavers. One of our neighbors had her backyard redone last year and had her concrete sidewalk broken up into urbanite:

The advantage of urbanite is that the cracks between the slabs allow water to seep in rather than run off as a sheet. This recharges the water in the garden and reduces the load on the city storm drain system. Plus, it looks much nicer than a single slab of concrete.

So our plan now is to reset the concrete slabs as urbanite in gray decomposed granite, and not dye them, since the current color matches the driveway and the rest of the sidewalk. For the water drain, our garden designer, Chris (from Garden Escapes by Chris Todd) recommends a small gravel-filled channel level with the urbanite surface rather than a pipe. This will drain down into a pebble filled faux streambed in the small strip garden where the water can filter in. Chris will be in charge of resetting the paving and redoing the side garden once PG&E is through.

More Accurate Solar Cost Accounting

2011-01-30T12:14:00.000-08:00

My previous post updating the results of our ten year struggle to reduce our carbon footprint mentioned that I was not satisfied with the cost accounting for our previous and current solar PV system. The percent reduction chart showed a 33% reduction in our carbon footprint between 2003 and 2004 due to the 2.5 kw solar PV system, and a per kilogram lifetime carbon reduction cost of $0.43 over the projected 30 year lifetime of the system (though we only used the system for 6 years). For the 7.05 kw system we are currently installing, the projected reduction is shown as only 0.05% and the lifetime per kilogram cost is shown as $2.10 over the projected 30 year lifetime of the system. The calculations were based on measured or projected reduction in electricity use from the year before to after the system was installed. These results made little sense to me, because the cost of solar PV has come down dramatically in the last 10 years, even though the subsidy has dropped even more.

The problem with this calculation is that the original system was installed along with other improvements, including removing the pool, replacing many of the lights with CFLs, and replacing the washer and dryer with more energy efficient models. The reduction due to these measures was not broken out. For the new system, as mentioned, we still are projected to draw around 2000 kwh/year from the grid, but the actual amount is slightly less than we draw now. That accounts for the 0.05% reduction between before and after the system is installed, but the lifetime reduction cost did not account for the fact that the new system will also be offseting the same electricity use as the old.

Unfortunately, I don't have actual figures for the amount of electricity generated by the old solar PV system, since I did not write down the production amount recorded on the SonnyBoy inverter before it was decommissioned, and the PG&E bills (upon which most of my measurements are based) do not break out total usage from usage net of solar production. But based on the carbon calculator at Altstore.com, I calculated the expected energy production for the 2.5 kw system at 3780 kwh/year, which amounts to 1.12 metric tons / year of carbon using the carbon calculator at Cool-it.us. Here, again, there are some inaccuracies. The Altstore.com calculator might be too optimistic, and the Cool-it.us calculation is based on the current mix of energy sources in the California grid. Since the grid has become greener over the last 10 years, the actual amount of carbon eliminated could be more. The other measures we took in 2004 - removing the pool, CFLs, and appliances - then account for 1.193 metric tons of eliminated carbon, slightly more than the solar PV.

The effect of this change on the lifetime cost of our current PV system is then rather dramatic (and more likely to be correct) as the following graph shows:

This graph shows the cost of the 2004 system, $0.54/kilo, as slightly greater than the cost of the 2007 system, $0.46/kilo. The cost of the other measures is around $0.34/kilo. For the other measures, I've estimated the lifetime as 30 years, even though the appliances and CFLs will have a shorter lifetime. The pool removal probably contributed the largest amount to the other measures, and its lifetime is essentially the lifetime of the house (actually probably more, it will be permanent) which is around 30 years.

Note that in the graph, the reduction in backup hot water carbon emissions is attributed to the "Reinsulate + on demand electric hw" rather than to the solar, even though the solar will be contributing the renewable power to offset the electricity used for backup hot water. But apportioning the costs between the two would be difficult, and since the backup hot water reduction would not be possible without the electric on-demand heater, the breakdown seems fair.

Anyway, the projected results from our current system remodel are mostly theoretical. It will be interesting to see over the next couple years how the improvements we've made actually impact our carbon footprint. The Tigo energy maximizer we'll be installing on the solar PV system has included a real time measurement package that records the amount of power generated on a web site, so we should now have much more accurate data in an easy to access form. The gas usage data will unfortunately be not much changed than before, since it will come from the PG&E bill, though we now have a SmartMeter for our gas meter which gives accurate, daily gas usage information on PG&E's web site. Perhaps if I get ambitious, I might try to do some Ajax hacking to consolidate this information in one place so I can display real time information about our energy usage and carbon footprint.

Ponzini Comes Through

2011-01-29T20:22:00.000-08:00

Last weekend, I sent Paul a plan with places marked that had problems with cracks and such as described in my post on insulation a week ago. I also sent him two zip files with photos, but, unfortunately, they were too big and didn't get through, and I didn't want to spend the whole evening last Sunday uploading them to Flickr.

Ponzini came by on Monday and fixed some of the problems, but not all of them. In particular, they finally sealed off the gap under the floor in the chase upstairs where the HRV is located. There were still a lot of cracks, though, and I did a walkthrough with Ponzini on Thurs. when Paul came by for the weekly meeting.

On Fri. they were out again, and this time they seem to have fixed most of the problems. They've mostly filled the cracks with pink foam. Here you can see how they fixed the small holes at the end of the beams in the ceiling, and the cracks between beams:

Paul says that the holes at the end of the beams and the gaps between two studs placed next to each other come from shrinkage in the studs and beams as they age. When they were originally placed, there was likely no gap.

Below, you can see how they've used pink foam to fill in a crack between two studs that were placed next to each other:

And here you can see how they filled out the foam along a header so it is level with the ceiling instead of only at the level of the wall:

This is important because the ceiling must be to R-30 whereas the walls are R-19. Heat leaks along headers are common if they are not properly insulated.

Finally, the cracks on the big headers over the doors were also filled in:

You can even see where they used acrylic caulking compound in the places where the cracks are smaller than 1/4". The foam can only be put in if the cracks are larger than 1/4".

There is still one place Ponzini seems to have missed, in the new hot water heater closet upstairs, but, by and large, they seem to have done a thorough job of fixing the problem areas. It is somewhat puzzling, though, that they didn't just do these without my having to hassle them about it. Are most of their customers not as picky? Do they just not see these problems and need me to point them out? They are not, by any stretch of the imagination, a "green" contractor, but they seem to know what to do when they are told where to do it. So I'm happy with the work they've done.

Update On Projected Carbon Footprint

2011-01-26T20:41:00.000-08:00

Since my last post on the estimated carbon footprint after our current system remodel and projected purchase of a Nissan Leaf, a few things have changed:

The design for the solar PV system was finalized,
Figures for yearly comparative gas usage with and without solar thermal hot water are available,
A more accurate cost estimate is possible.

So this post provides an update on the projected carbon footprint and cost per kilo carbon eliminated for our direct carbon emissions (except for flying) after the current system remodel is complete and after the Nissan Leaf.

Perhaps the biggest impact on our projected carbon footprint - upward unfortunately - came from finalizing the solar PV design. We now anticipate that the solar PV system will generate around 7,024 kwh per year. This is around 2000 kwh per year less than our anticipated utilization, considering the new HRV system, the new electric hot water backup, 8000 mi/year on the Nissan Leaf, and our existing utilization, including the plug-in Prius. Interestingly enough, 2000 kwh per year is almost exactly where we fall short of net zero today, though we will be offsetting considerably more carbon sources through the new system than we currently do. Since our solar resource will be maxed out with the new system, we have no more room to expand, short of new technology that generates more power per square foot.

On the positive side, the impact of solar thermal hot water on our hot water usage was considerably better than anticipated. With the current gas-fired tank as a backup, the solar thermal hot water system eliminated 23% of our yearly gas usage, rather than 15% as previously assumed. With the installation of the new electric on-demand hot water backup, the additional amount of gas consumed to heat water during the winter will be eliminated, reducing total gas consumption by 31%.

The assumptions in the projections are about the same as before. The result modifies our per cent carbon reduction graph as follows (please click on figures to get full picture):

Our projected carbon footprint reduction has decreased from 90% to 78%. This is primarily due to the reduction in expected solar power from the PV system. Previously, we had expected to completely eliminate our grid draw, and have a a 15% surplus. Now, we expect to draw around 2000 kwh per year from the grid.

The contributions from each component to our annual carbon footprint can be seen in this graph:

Since we are projected to use all the solar PV we generate, we no longer have a negative footprint due to generating more solar PV than we use. The expected size of our carbon footprint is around 2.8 metric tons per year. This is over twice the size of the carbon footprint (around 1 metric ton) that this Swedish family is shooting for. In our case the deciding factor is our plug-in Prius, which gets around 80 mpg but still generates around 1.1 metric tons of carbon per year. The Swedish family has a plug-in Volvo but no second car, since in Sweden, the public transport system is adequate for transportation around town if you don't need to haul anything. In addition, the Swedish electrical grid is 52% carbon free, due to hydropower and nuclear energy, whereas in California, it is considerably less (but better than many other states which generate electricity using coal), maybe around 30% including large hydro and nuclear.

Finally, the cost per kg carbon eliminated over the life cycle of each technology employed:

I've included more technologies here than in the original post, in fact, every technology we've employed since we moved into the house in 2003. Note, however, that I still do not have an accurate partitioning for how much the reduction in 2003 was due to the original solar PV system and how much was due to eliminating the pool. I'm working on estimating that. For this reason, the original solar PV system looks considerably cheaper than the current system, but it is probably about the same price or somewhat cheaper, considering that the cost per watt has decreased and we are installing more capacity, and that the grid is getting greener. Another point to note is that the price of the 200 amp upgrade has been distributed between the Nissan Leaf and the on-demand electric hot water heater, both of which require 200 amp service. I've also included the price of carbon offsets to make up for the GHG emissions during closed cell foam installation. Otherwise, the assumptions are the same as in the previous post.

So we're projected to fall somewhat shorter of our net zero goal than originally planned, but we are projected to achieve 78% carbon reduction, from the 2001 baseline. This is just 2% short of the general policy goal expressed by many analysts of reducing carbon by 80%. Time will tell whether we can do better. Through efficiency, like bicycling in summer instead of taking the car to work, perhaps we can reduce even more, and some of the technologies, like the closed cell foam insulation and HRV, may turn out to be more effective than originally thought. I'll be monitoring our gas and electricity usage to see how much reduction actually occurs.

Insulation Problems

2011-01-23T20:53:00.000-08:00

Well Ponzini finished the insulation this week, for some definition of the word "finished". I went through the house and made a close inspection of their work, and I have to say I am Not Pleased. They left lots of cracks and gaps, some of them so obvious that it is pretty hard to see how they could have been missed.

Here's some pictures to show what I mean. Every window and door has an uninsulated crevice around it like this one:

We also have a lot of places where there are two structural members right next to each other with a narrow crack between them. In all of these cases, they neglected to seal up the crack, like this crack in the corner next to a window:

The same goes for cracks between headers and other structural members over the doors:

And in the Bedroom3 chase upstairs, there is even a place where I can shine a flashlight through the crack. It's the blurry light in the middle (sorry, my old point and shoot doesn't have image stabilization in it):

There are gaps between the roof rafters and the main rafter running along the spine of the house:

And in a couple cases, the insulation on the 2x6 walls doesn't look like it's R-19:

Finally, that place in the HRV chase where the old forced air ducts dive under the floor was not properly done:

They will probably need to staple in a piece of plastic and foam over it to seal the hole against air penetration.

Now, I have to say, if I was building a house, I would never build it with these kinds of gaps and cracks. Most houses today aren't built this way, so they are probably easier to insulate. But we have to work with the house we have. Ponzini did a walk through before they bid the job, and we warned them we wanted all the cracks sealed. It's not like they took the job when the drywall was on, then were surprised when they faced a lot more work than they anticipated when the drywall was taken off.

Ponzini is supposed to come back with Paul tomorrow, and I've sent Paul an annotated house plan with locations of all 45 pictures I took, plus 2 zip files with the pictures (43Meg of pictures). We'll see what they do.

Making Closed Cell Foam Green

2011-01-19T21:12:00.000-08:00

If you recall this post, I talked about how the process of insulating our house with closed cell foam would result in the emission of HFC-245fa, a Green House Gas (GHG) with around 1000x the warming potential of carbon dioxide, but which decays from the atmosphere very quickly, in 7 years instead of 400. My solution to reducing the GHG footprint is to track the amount of the B chemical used, which contains the GHG, to calculate the carbon dioxide equivalent released, and then to buy carbon credits of a variety that will take carbon out of the air for up to 80 years, long after the HFC-245fa has decayed.

But carbon credits are always a last resort, when you don't have a choice: flying, whatever part of your gasoline usage you can't get rid of through an electric or hybrid car, and, as in our case, fossil gas and electricity drawn from the grid that can't be offset with renewables or eliminated by efficiency. It would be really great if we could figure out some way to make closed cell foam more green and, in addition, make it more accessible to the average home owner. So here are some thoughts along those lines.

Closed cell foam is a really super insulating material. It's positive properties are:

Inexpensive relative to even better insulators, such as aerogel
Nontoxic
Best insulating value of any affordable material (R-6/inch, approximately)
Easy to install
Functions as an air and vapor barrier
Can be partially made with recycled and plant-based material

It would be really great if we could figure out some way to reduce its negative properties:

Costs 2-3x as much as fiberglass batt, which is a lousy insulator
Uses petroleum for the part that is not recycled and plant-based, unlike alternatives such as blown cellulose, which is completely made of recycled material
Installation releases HFC-245fa, a powerful GHG

Some folks would include the fact that it burns when exposed to flame as a negative, but I don't necessarily see that. Fiberglass batt doesn't burn, but the paper casing will, and of course so will the studs and other structural materials in a house. As long as there are no additives that produce toxic fumes, the foam itself will simply combust to carbon dioxide and water. Most houses these days have far more stuff in them that will produce toxic fumes when burned.

Let's walk down this list one by one.

First off, cost. I frankly have no idea why closed cell foam is so expensive. Cost for a particular product or service is generally the sum of the cost of materials, cost of equipment (amortized over some period of time), and the cost of labor.

Is it because the materials that go into closed cell foam are more expensive than fiberglass batt or blown cellulose? I can imagine that they might be somewhat more expensive because they are specialized chemicals, but 2-3x more expensive?

Is the equipment more expensive? Ponzini parked a trailer in front of our house that contained the spray equipment. Though I didn't see their equipment, I've seen it before when we had open cell foam sprayed into the garage and attic wall. It is obviously more expensive than a staple gun, but I wonder if it is more expensive than the spray device they use to install blown cellulose? And, in any event, they can amortize it over a lot of jobs.

Is the labor more expensive? It took Ponzini maybe 6 days, 10 AM to 4 PM, to finish our house (well, let's put it this way, they think they are finished, the thermal imaging test will tell if they really are). I can't imagine that it would have been any more or less time than if they had installed blown cellulose or fiberglass batt. Actually, I think it probably would have been more time with either because both require that the installers actually get up to the walls and staple something on: the batt itself for fiberglass batt or netting to keep the cellulose in with cellulose. With foam, they just need to aim the spray gun and fire. It's certainly messier, bits of foam end up everywhere (including in our front driveway where they would pose a menace to aquatic wildlife if they got into the bay) but I'm sure fiberglass batt and blown cellulose installation have their unpleasant aspects too.

Aside from a possible slight difference in cost of materials (and of course absent any hard data), my conclusion is the exaggerated price difference between lousy insulators such as fiberglass batt and closed cell foam is simply because closed cell foam is a "premium" product and therefore must command a "premium" price. In other words, you get what you pay for. To get the same air and vapor barrier function as closed cell foam with batt or cellulose requires all the cracks in the building's thermal shell to be sealed and the installers to pay close attention to how they are installing the material, all of which would make batt and cellulose more expensive too. Such measures won't increase the R-value of batt or cellulose, of course. In any case, I'd certainly like to find an insulation contractor who wouldn't mind someone taking a look at their cost structure and really getting some hard data on the topic. After all, if the computer industry pricing and cost structure worked the way the building industry seems to work, we would all still be using PCs with 386s and 640K of RAM because the fast Pentiums would be way out of our price range.

Next, use of petroleum. I'm no chemical engineer, but I think that there should be a way to increase the recycled and nonpetroleum content of closed cell foam. Demlec already advertises that it uses soy oils and partially recycled content in its product. If I were an academic with a chemical engineering background, I'd be writing grants to EnergyARPA and the Energy Dept. to do research on the topic. And, let's put it this way, the long term future of petroleum-based products is pretty much known: they will shortly be gone. According to the International Energy Agency, we'll be almost out of oil by 2050.

Finally, GHG emissions. On the face of it, this seems like it might be the most difficult point, but actually, its the easiest. HFC-245fa is used because it's nontoxic, much heavier than air (so the bubbles expand more slowly), and relatively inexpensive. It's a good choice, except for the greenhouse gas problem. If there were some way we could keep it out of the air...hmm...this brings to mind something that happened when we first bought our house.

The roof had termites. So we had to have it tented. During tenting, the pest control company encases the house in a large, closed tent and fumigates with sulfuryl fluoride, which is extremely toxic to anything that's alive (we had some plants damaged when we had it done) and is itself a green house gas 4800x as powerful as carbon dioxide. There are now more environmentally benign alternatives, we didn't investigate them at the time, since they probably didn't exist.

Why not enclose a house undergoing closed cell foam insulation in a large tent, sealed as tightly as possible, just like when tenting for termites? While the foaming is going on, a blower can pull air out of the house containing the HFC-245fa and exhaust it through a system that recovers the GHG for reuse. It might also be burned, but the fluorine in the HFC could end up as hydrofluoric acid, which is really nasty stuff. Left behind is the HFC in the foam bubbles, some of which will outgas over time, but the amount that's released during such aging should be much less than during installation. This could then be offset using carbon credits.

Tenting will add something to the cost, but if my suspicions about why closed cell foam is so expensive are true, the cost could still be reduced enough that closed cell foam should become much more competitive with fiberglass batt.

So there's some ideas about how to make closed cell foam cheaper, less impact on non-renewable resources, and less GHG-polluting.

Skylight Shade Problems

2011-01-13T20:30:00.000-08:00

Things seem to be coming along. REC removed the old solar panels and my friend Bill took them up to Mendocino County. It felt like when I traded up my first PC, a grey no-name PC-AT clone with an upright black and white Xerox monitor, for a Pentium with a color monitor: a bit sad to see an old friend go but at the same time exciting that I'm getting new technology that costs less and performs better. All that is left is a pile of mounting rails:

We'll take those up to Bill's in April or May on a weekend trip to Mendocino County.

The roofers fixed the roof where the old solar panels were removed, since the rails used back in 2004 when we had our system installed were not as well designed as today. We had some leaks in the roof, one of which caused a mold problem that we only finally got fixed in 2009. There were a couple leaks after the roofers were done, but we found them in the leak test. Ponzini has started insulating the interior, they have the Buddha room almost done and have started on the living room.The big mystery right now is: where's PG&E? They seem to have disappeared over the holidays. But we were told this week we will get a date for the 200 amp upgrade on Jan. 17. Hopefully, the upgrade date will be soon. I'd really like to get back into the place by the end of March.

Better news: I got to order my Nissan Leaf! The process was fairly painless, through a form at the Leaf web site on which I have an account due to my registration. I opted for the 440V fast charger, in addition to the 220V and 110V chargers, since I'd like to be able to take it up to Pt. Reyes or down to Monterey some day when the charging infrastructure is in place. Today, the dealer called and asked a couple questions. He told me there have been some problems in the initial distribution (which I had read about on plugincars.com). In December, Nissan reconfigured part of a factory in Japan to build Leafs (Leaves?) because demand was running much higher than expected, and that pushed out the deliveries. The dealer told me that the car won't sell like a regular car - where the dealer has inventory and you go in and buy out of that - for another 2 years. This is very encouraging for electric cars, they seem to have much more demand than I originally had thought. I'll have to wait 4 to 6 months for the car, and in March they'll have a demo model at the dealer which I can try out.

But on to the subject of this post: skylight shades. Part of the work we were intending was to install motorized shades in the skylights that adorn the ridge of our roof. They are at the top of the cathedral ceiling in the hallway, which is where most of the warm air collects. In summer this is great, because we can open the middle skylight and all the hot air simply exhausts itself out of the house. But in winter, it's not so good because we lose a lot of heat through the windows. The HRV exhaust ducts will reduce the amount of warm air by redistributing it downstairs and to rooms upstairs, but the skylights will still act as a heat radiator on cold winter nights. I would like to have some motorized insulating shades on a timer that will close after sunset in winter and open at sunrise.

Here is a picture of one of our skylights:

The yellow cable you see hanging down is intended for the motor. Each skylight has one now, replacing the useless ceiling fan we had in place before.

The geometry of our skylights is a bit peculiar. The skylights form a triangle, as does the bottom of the frame box onto which the skylight is installed. So there is no part of the frame that is square where we can install a shade motor.

On top of this, the products on the market seem mostly to be for skylights set at an angle and not horizontal as ours is. Most of the companies we talked with seemed to want us to have two shades that ran directly against the glass. But this wouldn't work for the middle skylight, it opens. Even for the others, there is no real place along the spine that would be big enough for a shade track that sealed. The final problem seems to be that Hunter-Douglas, apparently the largest manufacturer of shades of all sorts, discontinued a certain motor that would have been the right thing for us.

Aside from the geometry, I'm having a bit of a problem seeing why nobody makes a product that would fit our case. It seems fairly straightforward. At any rate, we've pulled Christine off the trail since she was spending a lot of time coming up short, and it was costing us money. She has one more contact to follow up, a guy who makes his own motors. If that doesn't pan out, I'm going to look into what I can find, maybe ultimately I'll end up with a DIY solution if I can't find a product that works.

Solar Tradeoff

2011-01-10T19:59:00.000-08:00

After writing my last post about the new solar PV design, while I was riding my bicycle on my usual Saturday trip to the Palo Alto library, I got to thinking about the tradeoff we implicitly made in our use of solar. We have a fairly limited solar resource due to the large redwood trees in our neighbor's lot on the south side of the house, and due to the orientation of the roof axis, which runs more or less north-south instead of east-west. The redwood trees are great in summer, since they allow us to have a glass sun room on the south side of the house where we can enjoy our beautiful California native plant garden (maintained by The Lovely Wife). If the trees were not there, the sun room and in fact the south side of the house would be much too hot in summer. However, because the south side is so heavily shaded, it does not represent a particularly good solar resource.

Most of our solar resource is therefore on the north side of the roof. The orientation of the roof axis means the roof slopes to the southwest and northeast, causing the solar panels on the north part of the roof where the solar resource is to only receive full sun during part of the day. The southwest slope has sun in the afternoon and the northeast slope has sun in the morning. In summer because of the high sun angle, there is enough sun that the panels are fully illuminated for most of the day, but in winter the low sun angle means they only get sun for maybe 4 hours on the east and 5 on the west. If the roof axis ran east west and there was no shade on the south, we could in theory get 100% sun all day in summer and winter and we would have a much better solar resource.

So given that limited solar resource, we've chosen to utilize it by having a 2 panel solar thermal hot water collector near the peak on the northeast slope, with 10 solar PV panels below, and to populate the southwest slope with 20 solar PV panels. I actually didn't run a complex software program to calculate the tradeoff, or even give it much thought; it just evolved as we evolved our renewable energy systems over the years since we bought the house. We put the 2.5 kw solar PV system in place when we moved in in 2004 because residential solar PV was just getting started and I have wanted a solar PV system for years to get started on reducing our carbon footprint. It was right-sized for our usage at that time, and about all we could afford given that solar PV was expensive. We put the solar thermal system in last year because reducing our carbon footprint even more through reduction of natural gas usage seemed like the next step. And we are putting the larger solar PV system in now because solar PV has come down radically in price and the performance has almost doubled since we put in our original system, just like PCs in the 80's. But we could have done things differently if we had designed the system to utilize our limited solar resource in a single step, rather than installing it incrementally.

What if, instead, we had populated the entire roof with PV panels and not installed the solar thermal hot water collector?

There are of course a couple ways one can look at this tradeoff. The most obvious way is to ask how much cost reduction in energy use the solar thermal provides in comparison to the solar PV. But this is actually the least useful comparison. Natural gas is cheap and electricity is much more expensive per unit of energy delivered, which might argue for having more solar PV instead of solar thermal. But, on the other hand, because the net metering tariff rates pay us 3x for power we generate on summer afternoons compared to power we use at night and in the winter, our new design with 20 panels on the southwest slope and 10 on the northwest should ensure that, as is the case today, we don't have a bill even though we may end up drawing more power from the grid than the solar PV system generates.

A better way to look at the tradeoff is to compare the amount of carbon eliminated by the solar thermal hot water system compared to the amount eliminated by the extra panels that we could have installed. To do that, we must calculate the amount of carbon eliminated by the power the extra panels would generate, and compare that to the amount of carbon eliminated by the solar thermal hot water system.

The solar thermal system take up about as much space as another row of 5 panels. How much extra power would 5 panels generate? The existing 10 panels on the northeast slope will be generating around 2462 kwh/yr or 246.2 kwh/panel/yr. So an additional 5 panels should generate 1231 kwh/yr. This isn't enough to net out our estimated usage, unfortunately. My calculations show that our new design will be around 1807 kwh short as reported in the last post, which is power we will have to draw from the grid if we use it. However, those panels would certainly make it more likely that we might actually end up zeroing out our carbon footprint for electricity.

How much natural gas does the solar thermal hot water system actually save? Well, from 8/2007-7/2008 we used 465 therms of gas. That was the last full year before we installed the solar thermal hot water system. From 8/2009-7/2010, we used 356 therms of gas, for a reduction of 109 therms. That is around a 23% reduction. Now, this is only one year and our gas usage tends to fluctuate quite a bit from year to year, much more than the electric usage. In an El Nino year, the winter might be warmer and we use less gas. In a La Nina year, like this one, the weather is colder and we use more. With the electricity, the stuff we do - like using the computer or charging the plug-in hybrid - is pretty much the same year to year, with seasonal variations. In winter the lights are on longer and the pumps for the hydronic heating system are on, while in summer these sources of electricity demand are absent.

Calculating the carbon savings from these two alternatives shows that we really made the right decision. 1232 kwh/yr of electricity generates around 802 lbs/yr of carbon in California (your mileage may vary depending on the carbon footprint of your local grid). 109 therms/yr of natural gas generates 1276 lbs/yr of carbon regardless of where you are. California's grid is pretty green and will get greener now that Proposition 23 was shot down. Natural gas, on the other hand, will not get any greener, it is fossil carbon and will always bloat out your carbon footprint.

If offsetting our natural gas from hot water heating reduces our carbon footprint more than the electricity from solar PV, what about if instead of the solar PV, we install two more rows of solar thermal collectors and use the hot water for the hydronic heating system? Would that have been a better alternative than the solar PV? Unfortunately, no. Most of our sun comes in the summer, and the heat generated during the summer from a solar thermal system for space heating needs to be discarded somehow. The electricity generated from the solar PV in summer goes into the grid and helps reduce the carbon output from peaker gas power plants that power the air conditioners in the Central Valley. Heat from our hot water solar thermal system is used year round (in fact, we turn off our gas hot water heater in summer). In addition, the amount of sun we get on the roof in winter and when it comes is not enough to contribute any meaningful amount to reducing our winter heating carbon output. We need heat when it is cloudy, cold, and raining, exactly when there is no sun. So the solar PV is the right choice for rounding out the utilization of our solar resource.

Update on the Solar Design

2011-01-08T14:06:00.000-08:00

Lauren at REC sent me the final numbers on the three design options.

The ten panels on the northeast slope have 87% solar access and should generate an estimated 2,464 kwh per year.

The three design options for the southwest slope result in the following:

With the four panels strung out along the south side, the solar access is 80% and the annual power generation from the southwest slope is 4,245 kwh,
With the four panels stacked as 2 rows of 2 along the south side, the solar access is 80% and the annual power generation from the southwest slope is 4,290 kwh,
With the four panels on the top of the dormer, the solar access is 84% and the annual power generation from the southwest slope is 4,560 kwh.

So for the dormer option, the total power should be 7,024 kwh/year, about a 4% improvement over the original design.

The inital estimate based simply on the panel size and number of panels was 8,722 kwh. That means we will have 1,698 kwh/year less than originally planned, around 20%, primarily due to shading. There is nothing we can do about this (except maybe regularly trim the Polycarpus trees in our neighbor's yard that shade the southwest slope panels). I don't know if REC is including the effect of the Tigo MPP balancing system in the calculation, that could possibly increase the power production somewhat.

My original calculation for how much power we would need including the new electric car, the new hot water heater, the new HRV, and 2000 kwh/year we are currently drawing from the grid came out to around 5,000 kwh/year. The old 2.5 kw PV system was supplying around 3,831 kwh/year estimated. The total that I was trying to design for was 8,831 kwh/year. So we will be around 20% short of carbon neutral, but for that, we will be covering a lot of additional energy uses. That's better than the old system, where we were around ~~50%~~ 34% short. In any case, we should still have our electricity bill covered through net metering, since we'll be generating the most power during the afternoons in summer when the tariff is 3x at night, when we will be drawing power out of the grid for charging the car.

With this system we will have essentially maxed out our easily harvested solar resource. If we want to put any more solar PV up, we will likely get marginal return (both in terms of carbon reduction and financial) because the panels will be shaded much more, maybe even more than 50%. We will have to see how the system performs. Stay tuned.

Solar Design

2011-01-05T20:47:00.000-08:00

Our roof slopes in two directions: a southwest facing slope that gets most sun during the afternoon and a northeast facing slope that gets most sun in the morning. The roof spine runs on approximately a north/south axis. Our neighbor on the south side has a hedge of large redwood trees along the property line. In summer, the trees only shade the south side of the roof, but by late October, the sun is far enough down in the sky that half the roof gets almost no sun at all for most of the day. On the winter equinox, the northeast slope on the north side gets only 4 hours of sun in the morning, the southwest slope gets a bit more in the afternoon. In the summer, both sides get lots of sun for the whole day. Overall, our solar resource is adequate if not overwhelming, but these are the rough parameters we have to work with.

Our system has a total of 30 panels, and we need to optimize the amount of power the system will generate, given the constraints of our roof. The directional and large scale shading constraints above are one set. Another set is stuff already on the roof. This includes:

A solar powered attic fan to keep the attic cool,
Various vents from the kitchen and laundry room fans on the southwest slope,
The 2 panel solar thermal hot water system on the northeast slope we had installed last year,
Shading from the two dormers, one on either slope of the roof,
The skylights, which are actually along the spine running from the north side to central roof but do project slightly down the two slopes.

The current system consists of 18 panels on the southwest facing slope, but some of that space won't be usable with the new system. The new system will be slightly down from the ridge line since there are new building codes requiring a slight offset from the ridge so a fireman can chop his/her way into the house through the ridge in case of a fire. In addition, REC has calculated using their software system that panels which are currently in the bottom row on the southwest slope will be shaded too heavily by the west side neighbor's trees. These trees are pruned down heavily usually on an annual basis, but they grow back quickly and if we miss a year, like we did this year, they do end up shading more of the roof. So REC has figured that only 16 panels can go on the southwest slope where the current system is, two less than currently.

On the northeast facing slope, the solar thermal panels take up prime real estate on the top of the slope near the ridge. Having the solar thermal panels there is better than having PV, since this is the area that only gets 4 hours of sun in winter and the solar thermal panels won't heat up much if they don't get any sun. REC doesn't want to put any panels on top of the feed lines leading from the solar thermal panels to the house, so that leaves just the space on the bottom of the slope below the solar thermal panels. Space for 2 rows of 5 is available below the solar thermal panels, 10 panels in all.

That leaves 4 panels that still need placement. Since PG&E pays the best rates for power during summer afternoons, it makes the most sense to place the panels on the southwest slope. Given that, though, we want to optimize the amount of electricity generated regardless of the tariff, since we are constructing the system primarily to offset our carbon footprint.

So the first design REC proposed was with the 4 panels strung out along the south side of the southwest slope (the panels are outlined in magenta):

According to their calculations, the array on the southwest side has 80% annual sun and 20% shade while the array on the northeast side has 87% annual sun and 13% shade.

I asked them if they could do better, so they proposed two additional configurations. One has the 4 panels on the south side of the southwest slope, but stacked instead of strung out:

The other has the 4 panels on the dormer roof on the southwest slope:

REC doesn't have any calculations on top of the dormer yet, but they gave me estimates of the improvement. The stacked configuration would increase annual power production by 50 kwh/year while the dormer configuration would increase power production by 250 kwh/year. This amounts to around .6% for the stacked configuration and around 3% for the dormer configuration, figuring on 8722 kwh/year from the original REC calculation. 3% isn't much but it is something, so unless we can come up with some other configuration that does better, I will probably go with the dormer.

Tomorrow REC will remove the old solar panels and at that time they'll take a shade measurement on the dormer to get an exact value, so we should know shortly. Once the final design has been decided upon, REC will send it to the city and they'll take 2-3 weeks to consider sign off, provided there are no problems. Then comes the installation. After the installation, PG&E must certify the system (they don't have to install a dual ported meter in our case, we already have one) which should take a day or two (or three, PG&E has already taken 2 months with our request for a 200 amp service upgrade) and then we can turn on our new system.

Under Floor Insulation is Done and Skylight Shade Problems

2011-01-01T17:51:00.000-08:00

Last week, The Lovely Wife and I had a short but relaxing vacation in southern California. Seeing as it was the week between Christmas and New Year, I had every expectation that we would get back and not a thing would have been done during the week. After all, even during normal work weeks, very little seems to be happening. But Ponzini suprised us: they completed the insulation under the house and in the shelf under the living room windows.

Here's a kind of blurry picture of what the underside of the floor assembly looks like after Ponzini finished the spray foam, taken through the crawlspace access:

The pinkish white at the top is the foam under the floor, including a wire that got foamed. On the bottom you can see the bits of foam on the dirt. The bright white dots in the background are disco lights. Our crawl space is outfitted with disco lights so anybody who is working in it doesn't need to set up lights or try to use a flashlight. These were put in when the stapleup radiant heat system was installed.

I'd like to check out the job more closely but I try to avoid going into the crawlspace because it aggravates my allergies. I'll only go in if I really have to. Paul is going to check out the job Ponzini did to make sure they've sealed up all the cracks.

The space under the windows in the living room looked like this before Ponzini reinsulated it. Remember this picture from the Holes post:

Here you can see what passed for insulation in the shelf under the window: an inch of fiberglass batt with gaps where you can see the electrical wiring and drywall. Here's what it now looks like after Ponzini finished with it:

Because the cavity is so deep (at least a foot and a half) they didn't fill it entirely with foam. Instead, they stuffed it full with fiberglass and foamed over the outside of the fiberglass to seal it. The foam provides additional insulation as well as vapor, moisture, and air barrier. Unfortunately, Ponzini left little bits of foam in the garden next to where they foamed the area under the living room windows, which somebody needs to clean up.

So, going into 2011, progress is slowly being made. Right now, the completion of insulation on the interior is being held up by completion of some electrical work so the building inspector can certify the open walls. We are having a hard time finding motorized, insulating skylight shades that we will fit our skylights, so the wiring for them didn't get completed before the inspector's first visit. There were just three wire coils where the skylight shade connections should be. These need to be put into junction boxes until the skylight shade situation is clearer. It seems difficult to find insulating skylight shades that install horizontally and achieve a good seal so air doesn't penetrate the shades when closed. Most motorized, insulating shades are designed to be installed vertically, or, at least, at an angle less than 90 degrees to vertical. Such shades would fit on our skylights, but we would need two shades per skylight because the skylights are triangular. I don't think they would achieve a real airtight seal. Anyway, I am becoming increasingly skeptical that we will find shades to meet our requirements, but I want the electrical connection installed anyway. Appropriate shades might appear in the future, or we could ultimately end up using the connections for lights inside the skylight.

The other hold-up right now is PG&E and the 200 amp service installation. According to the Web site record they sent me, they were supposed to start on Dec. 24, naturally they didn't. So I now have no idea when they will start.

Finally, REC is supposed to come on Thurs. this week if the weather is OK and remove the old solar panels. After that, the roofers are supposed to come and fix the three holes in the roof that the old solar installer punched in 2004 when the first solar panels were installed. Considering that it has been raining off and on, with wind and cold since the beginning of December, I think the probability is high that this work may also get delayed, but we'll hope for the best. A week of sunny weather at this point would help the job along.

Green Insulation

2010-12-26T09:50:00.000-08:00

Normally, I don't spend much time factoring in the amount of carbon generated by manufacturing something that I'm going to use for carbon mitigation when figuring out how much carbon it will reduce. My reason is that we have to use the carbon-based technology we have to build the carbon-free society we want. Most calculations I've seen for, say, the amount of carbon generated by manufacturing solar panels v.s. the carbon they save over their 30 year lifetime indicate that the scales are heavily weighted towards massive savings in carbon emissions for solar cells. Even renewable energy sources with marginal carbon saving, such as corn-based ethanol, have become more efficient over the past 5 years. If you don't take indirect carbon into account - the amount of carbon generated by land that is put into production to make up for the land devoted to corn for ethanol - there is a savings, though not much. Indirect carbon accounting is controversial, however. If the same accounting method were used for other technologies, for example, the carbon generated by nickel mining to make up for the nickel that goes into a Prius battery, almost any technology would come out losing in the end. The people who came up with indirect carbon accounting were just looking for an argument against corn ethanol because they don't like the idea of trading off food for fuel with the population still headed upwards, and I agree totally. There are plenty of other ways to achieve a carbon free transportation network which don't involve that tradeoff, and we would be pursuing them more forcefully if it weren't for politics.

But a couple of nights ago, I came up hard against this issue of global warming gas emissions from technologies that are good at reducing energy use and thereby carbon emissions. I'm not talking about carbon here, but rather HFCs. HFCs are gases containing fluorine, carbon, and hydrogen that are used most commonly in refrigerators and air conditioners. They replaced CFCs after the Montreal Convention was passed, because CFCs were causing reductions in the ozone layer, an even more serious - but now thankfully receeding - environmental problem than global warming. HFCs have no impact on ozone but they are a global warming gas. Their impact on global warming can be many thousands of times as powerful as carbon dioxide. On the positive side, they do not remain in the atmosphere very long, around 7-10 years, unlike carbon dioxide which has a atmospheric lifetime of around 450 years.

I was interested in what impact our spray foam insulation might have so I sent email to Paul asking what product Ponzini used for their closed cell spray foam. As usual, he didn't reply so I checked Ponzini's web site and found a link to the product, Johns Manvill Corbond III SPF. I had done some research before on spray foam, and there are some green products out there, advertised as made from recycled plastic and soy oil, like Demlec. I had used Demlec in a previous open cell foam job to seal the wall between the attic/garage and the house. JM's Corbond doesn't appear to use soy oil, it's petroleum based, but, as mentioned above, using food crops for nonfood applications has some powerful arguments against it. JM's Corbond claims around 16% recycled content, that is about what Demlec claims too, even though JM doesn't make a big deal about being a green manufacturer. Quite to the contrary, their page on sustainability is filled with a lot of high minded rhetoric, but when you look at the pages on their products the information on ecological effects, such as about recycled content, is buried deep in the data sheets (for example, this data sheet on the B component of Corbond). Demlec, on the other hand, calls out this information in a completely separate page. Both Demlec and JM Corbond use HFC 245fa, a powerful global warming gas, as the blowing agent to blow small bubbles into the foam. So if you drill down on it, the only real difference between a "green" product such as Demlec and JM Corbond is the fact that the green product uses soy oil instead of a petroleum derivative.

I should say something about spray foam insulation here (unfortunately, there's no good Wikipedia page on this). Spray foam insulation comes in two basic types: open cell and closed cell. Open cell foam has a R-value about the same as fiberglass batt, R-3/R-4 per inch, while closed cell foam has a much higher R-value, R-6 per inch. Closed cell foam is the "gold standard" in insulation. Only aerogel does better, at R-10 per inch, it is the platinum standard. "Platinum" and "gold" here refer not just to their insulation potential but also to their cost. Spray foam, even open cell spray foam, is about 2-3x as expensive as fiberglass batt, while aerogel is completely unaffordable except for very limited applications such as my planned thermal bridging treatment. Both closed cell and open cell foam reduce air penetration, unlike fiberglass batt, but open cell foam is permeable to moisture while closed cell foam tightly seals against it, thereby acting as a vapor barrier.

The kind of foam insulation that we are having installed is polyurethane, a commonly available product used not only in home insulation but also for insulating refrigerators, hot tubs, coolers, etc. Prior to installation, polyurethane spray foam comes as two separate liquids, an A component and a B component. The A component contains a mixture of isocyanates while the B component is primarily a polyol with some other chemicals. When the two components combine, the two chemicals react to form polyurethane plastic. A blowing agent pushes the two chemicals together and expands to form tiny bubbles in the plastic. The tiny bubbles give the plastic its insulation value. Depending on the blowing agent, the result is either soft open cell foam or rigid closed cell foam. If the blowing agent is water, the result is open cell foam because the water reacts with the chemicals to form carbon dioxide, which expands rapidly resulting in a less dense foam with less insulation value. If, however, closed cell foam is desired, the blowing agent is HFC245fa. HFC245fa expands more slowly than carbon dioxide so the bubbles are smaller. But both types of spray foam insulation generate green house gases, however closed cell foam generates a gas, HFC245fa, with 1000 times the greenhouse gas potential of carbon dioxide.

The fact that the insulation would result in greenhouse gas emissions was, of course, somewhat depressing since the whole point of this work is to eliminate greenhouse gas emissions. However, as pointed out in this article, the net impact depends on how much global warming gas emission is eliminated by the treatment over the lifetime of the product. So I went about calculating what the rough impact was of the global warming gas emissions v.s. the amount of gas eliminated. I took the crude architectural model of the house I created a few years ago and measured the depth of the studs in all areas so I could calculate the volume of the foam that would be blown into the stud bays. For the floor, I estimated the area as 2500 square feet. Then I calculated out the volume of foam, correcting for the volume of the walls, floor and ceiling that are structural members, as described in the thermal bridging post. I came up with a volume of 1435 cubic feet, or around 1500 cubic feet. This is probably a bit high but should be a good enough estimate.

Closed cell foam has a density of 2 lb/cubic foot. This gave me the weight of the foam, around 3000 lbs. Of that, half is the B resin which contains HFC 245fa, or around 1500 lbs. HFC 245fa makes up between 7-12% of the B resin fraction. Taking the higher number, the amount of HFC 245fa released should be around 180 lbs. Since HFC 245fa has a global warming potential around 1000x carbon dioxide, this would amount to around 180,000 lbs, or 90 English tons, of carbon dioxide. Then comes the question: how much carbon dioxide will be eliminated? That is harder to calculate, but I've estimated that R-6 per inch foam insulation in our walls should reduce gas usage by around 30%. Using that as the figure, the insulation should eliminate 106 therms/year of gas. At 11.7 pounds of carbon per therm, that's 2907 lbs of carbon per year, or around 3000 lbs rounding up. So it will take 60 years for the house to break even from the HFC245fa released during the insulation.This was truly distressing. Here I am trying to do the right thing and reduce the carbon footprint by making my house energy efficient and the technology I've used will take 60 years before there is breakeven in the carbon emitted by the insulation!

So what were the alternatives? We had originally planned to install a geothermal heat pump with blown cellulose insulation in the walls and spray foam only in the ceilings and the floor. Geothermal heat pumps use HFCs too, and can leak them slowly out in the atmosphere, but not as much as spray foam. But the geothermal heat pump turned out to be too expensive and too complex. We could have continued with blown cellulose, but it does not achieve an air barrier and is therefore much less effective than spray foam. It is possible to make a house air tight with blown cellulose, but it requires going over the entire house and sealing up all the cracks in the siding. In addition, most newer houses have complicated vapor barriers on the exterior between the siding and plywood sheathing. Our house has no plywood sheathing, there is just the exterior plywood siding and the interior drywall, with a thin layer of tar paper under the siding. This is a rather poor vapor barrier, even in California's Mediterranean climate. So the spray foam should give us a much better vapor barrier. Blown cellulose also has a tendency to sag over time, and completely loses its insulation value if it becomes wet. Finally, spray foam increases the structure integrity of the building envelope, an important factor when considering earthquake.

So having foam insulation has some really desirable properties which we don't want to give up. In a situation like this, my feeling is the best solution is to pay for carbon offsets. It's like flying, in some cases there are alternatives to flying (taking a train or driving for example) but they are often impractical. We offset our our familial carbon emissions for housing and transportation every year anyway. We use carbonfund.org, a nonprofit, which means our carbon offsets are tax deductible. As it turns out, the carbon emissions from our insulation job should be about what a family of 4 in the US emits in one year, which in and of itself is kind of sobering. The cost at $0.004/lb is around $810. So next year, after the insulation job is finished, I plan to send a check to carbonfund.org for the carbon offsets. Carbonfund.org lets you select the type of offset, so I'll select forestry to establish a long lasting sink for carbon that will span the 60 years that I hope our house will still be around (though of course I'll be long gone).

I've asked Paul to get the amount of the B resin used by Ponzini so I can refine the estimate, and I will report on the exact amount when I have it.

Yet More Drywall Removal

2010-12-23T20:49:00.000-08:00

Last week, I suddenly realized that we might not actually have all the drywall removed from the thermal envelope. The front of the front upstairs bedroom sticks out slightly from the plane of the house, like a dormer. You can see it in this photo below:

This is about a two foot section where the bedroom has an exterior wall rather than sharing it with the attic.

When I went upstairs to check, sure enough, the drywall was still on. So the drywall removers had to come yet again. Here's what it looked like on the west wall when they were finished:

The round white target shaped thing on the top is the HRV vent.

Sigh. Hopefully, this will be the very last time we will need to have the drywall removers here, because Ponzini has started doing the insulation underneath the house.

Thermablok and Thermal Bridging

2010-12-22T19:28:00.000-08:00

While mold most often occurs where there are roof or siding leaks, it also occurs when warm, moist air contacts cold structural members, causing water to condense out. We found mold on the face of a stud in the south hallway wall. The south hallway wall receives no sun in winter so the outside wall doesn't warm up during the day and, as a result, likely gets much colder at night. When mold occurs on a stud and there is no evidence of any siding leakage (as in this particular case) it is probably a result of thermal bridging. Insulation won't help because it is installed between the studs, and it won't stop heat transfer through the face.

I discussed thermal bridging in this previous post. The conclusion was that it would be too expensive and difficult to treat the whole house for thermal bridging, besides which, the insulation and drywall contractors probably wouldn't know what to do. However, I do want to treat the south wall of the hallway, to eliminate the condensation problem. So I ordered 50 strips of Thermablok , which I described in my previous post, enough to face the studs on the south hallway wall. Thermablok is an aerogel insulation that comes in 4' by 1.5" strips. The back of the strip has adhesive on it. Installing it couldn't be easier: you peel off the plastic strip and paste it onto the face of the stud (making sure of course there is no drywall dust or other dirt on the stud to clog up the adhesive). Aerogel is the most effective insulating material after vacuum, at around R-10/inch. These strips will add R-4 to the studs, effectively doubling the insulating value of a 2x4. But aerogel isn't cheap, the strips are about $4 apiece.

On Fri., a package arrived with the Thermablok. The guys at Acoustiblok (the company that sells Thermablok) like packaging. The entire thing was packed in heavy cardboard with duct tape on both ends. Inside that, the Thermablok strips were bundled together in plastic garbage bags that were also duct-taped:

Inside these, the Thermablok strips themselves were packages in shrink-wrap:

Here's a closer view of the label:

I took the strip and set it against a stud to see how it would look when installed:

Here is a closer view of the bottom:

The old drywall was not removed under the molding, so you can see how the Thermablok strip will line up with areas where there is still old drywall. Only about 0.1" of space separates the face of the old 0.5" thick drywall from the 0.39" thick (after the plastic strip is removed) Thermablok strip.

This is a problem. The thinnest drywall you can get is 0.25" and that is not recommended on framing with 16" centers The recommendation is for 0.5" thick drywall, probably because drywall has very little structural strength, and 0.25" therefore has much less strength that 0.5". So if 0.5" drywall is installed, the new drywall will stick up 0.4" beyond the existing drywall and various other stuff on the wall (electrical sockets, window sills, etc.). I looked around for alternative wall covering material that is thinner than drywall, but there doesn't appear to be much of anything. If we were planning on doing thermal bridging treatment for the whole house, this problem could cause a lot of additional work. All the molding would need to be taken off, maybe the electrical boxes would need to be moved, etc. But since we are only planning on doing one wall, the amount of work should be fairly limited.

Hydronic Radiant Heat Systems and Foam Insulation

2010-12-20T18:41:00.000-08:00

Our radiant heat system is what hydronics contractors call a "staple up". We have a crawlspace and the house originally had forced air heating. Unlike houses with radiant installed from the start, where the heating pipes are threaded through a poured concrete floor or slab prior to pouring the concrete, the pipes in our case are fastened to the subfloor. The contractor who installed our radiant system crawled around under the house for 2 months threading pipe between the joist bays beneath the floor.

For insulation, he stapled polyethylene/foil bubble wrap radiant barrier insulation immediately under the pipes, with a small gap to allow the radiant barrier to function properly. Below that, he installed 4" of fiberglass batt. The house previously had fiberglass batt insulation under the floor, but, as I've mentioned before, fiberglass batt is a poor choice for insulation, and even worse in an application such as this. It has a tendency to sag, and in this case, because there is nothing across the bottoms of the floor joists, the tendency is even worse. In a wall-based application, at least the drywall is holding it in place, but I think the insulation contractor used fishing line or something to hold it up.

So as part of our quest to tightly seal the thermal envelope in our building, we decided to have closed cell foam blown into the spaces between the floor joists, just like in the walls and ceiling. But the situation is more complicated there, we can't simply foam on top of the pipes, since there needs to be some clearance. The foil radiant barrier provides that clearance, but will it withstand the pressure of the foam expansion? At first, Forrest, our architect, thought not, so we discussed installing some metal plates in place of the foil radiant barrier. But Paul said that would result in a much larger expense and delay. I asked Paul whether Ponzini, our insulation contractor, could do a test item that would determine whether installing the foam on top of the radiant barrier would work. Here's a picture of the test item:

The test item consists of two 2x8's with a plywood top simulating the floor assembly, and some radiant barrier stapled partway down. Below, you can see the radiant barrier and the gap:

The foil radiant barrier seems to hold up well, the foam pressure isn't enough to collapse it. So we are going forward with foaming on top of the radiant barrier. I have, however, asked Paul to check whether there is enough clearance on all the pipes and to ensure that the barrier is firmly stapled in place and hasn't collapsed in the 4 years since we had the hydronic system installed.

One issue that does concern me is leaks. A large earthquake could separate the PEX tubing from the manifolds and zone pumps. Leaks within the PEX tubing are less likely, but still possible if a pipe fails due to long term deterioration. With closed cell foam insulation, the water would accumulate between the insulation and subfloor, ultimately leaking out upwards and possibly warping the subfloor. The only indication of a leak is that the hydronic system starts drawing a lot of water out of the domestic water supply and the system pressure gauge indicates a drop in pressure from the normal 7 psi. But the pressure gauge is in the hydronic closet and we mostly don't look at it (though of course if there is a large earthquake we probably will check it to make sure the system is OK).

I briefly searched the Web for some water sensors that we could put into the floor to detect a leak directly. They all require replacing AA batteries at periodic intervals, a nonstarter since the sensors would be sealed into the floor by the insulation. This is a general problem with current sensor technology. If you want to put a sensor in an inaccessible place, even if it could have a wireless data connection, you still need to supply it with power through a wire. I called Kevin Smith, our hydronic contractor (he now has his own company, IntuitiveClimateControl) to discuss options and he said there are a variety of sensors we could put on the water line to the hydronic system that would measure and report if the hydronic system began to draw water at an accelerated rate. So when we finish the job, I'll probably look into putting in a sensor, but not now. There are too many things to finish up, and we just want to get this job done so we have our living space back.

Neither Paul nor the insulation contractor seemed to know much about our situation, which leads me to believe that they haven't run up against a hydronic stapleup that needs closed cell foam. I wonder if anyone else has tried closed cell foam insulation together with a staple-up hydronic system?

Duke Comes Through (Sort of...)

2010-12-19T18:15:00.000-08:00

A couple weeks ago, our good friend Duke came through and fixed the problems with the HRV venting... sort of. In the front, he cut a new vent, which is supposed to be for the HRV exhaust, below the attic vent. He hadn't switched the actual ducts yet, so the intake duct was connected to the new vent rather than the exhaust, but he knew about the problem and was planning on switching the ducts around when he came back to install the fitting on the condensate drain. Apparently, Fantech forgot to ship a condensate drain fitting along with the HRV unit. Duke ordered it, it was supposed to be here that Fri. Unfortunately, our good friend Duke is lacking in, shall we say, aesthetic sense. The concept of "curb appeal" is lost on him. Consequently, the front of our house now looks like this:

The new duct is about 3 inches lower than the old one, instead of nicely aligned. Rather than try to fix the problem, which would involve filling in the hole, we're simply going to paint the ducts the same color as the house and leave it at that. They should blend in enough with the house that they won't be all that visible. We also needed an electrical outlet to plug the front HRV in, but that's the electrician's job. He was supposed to install it that week.

Speaking of aesthetic issues, the HVRs require piping to drain off any condensate that might occur on the heat exchanger. The missing fitting is what was holding up the front HRV. Since the HRVs are installed in attic areas without any plumbing, there needs to be some way to get the water out of the HRV and drained away. Here's what our back condensate piping looks like:

The white pipe coming out through the wall is the condensate drain. You can also see the solar panel for one of our solar garden pumps near the top. This white pipe doesn't look so nice either, and will ultimately be painted. The pipe is unfortunately PVC. PVC is not a particularly environmentally friendly material. I asked Paul why they couldn't use ABS pipe instead, but ABS doesn't come in the 1/4" diameter stock that is needed for this application.

On the back, we now have a veritable proliferation of hoods:

Only the one on the lower right and upper left will ultimately stay. The others will disappear when the siding is replaced in the triangle on the right side of the picture. Then they will recut the vent on the lower right, which will be an attic vent. The upper left vent is the HRV intake. The HRV exhaust has moved to the roof:

It should be the tall one, the small one is the bathroom (high speed) exhaust. Below you can see how Duke rerouted the bathroom exhaust duct out the roof:

It is the hard, elbow-shaped pipe running up the middle of the picture. The exhaust is the soft duct on the upper left.

As they came from Fantech, the SH704s have no low voltage switch. You just plug them in and they start up. I'm not sure what Fantech had in mind as far as control. A Web search turned up the Aubetech 1702-3W which is a three wire, high voltage (i.e. 110V), 7 day timer switch with maximum 2 settings per day. I ordered and received 2 Aubetechs for the HRVs. They are rated for up to 1 HP motors, the Fantech motors are less so there should be no problem. This will allow the HRVs to turn off during the day when we are at work, and on again in the afternoon. The electrician needs to wire them up yet. We are going to put them into the closets in the bedrooms nearest the HRV units, so they are not visible from the room.

I also started the HRV above the master bedroom and, to my surprise, there was no problem with vibration at all. While the actual HRV unit itself vibrated due to the fan motor, the vibrations were not transmitted through the shock absorbers to the house frame. There was a very faint noise in the downstairs bedroom, about what we hear when the solar thermal pump goes on, which I assume was from vibrations transmitted through the air to the ceiling. With closed cell foam in the ceiling and additional soundproofing, I think the noise level should be OK.

This week, Paul, Christine, and I checked the HRVs and it seems like everything has been properly installed. The ducts are routed out the right vents, the front HRV has an outlet, and the condensate drain is in on the front HRV. The electrician still needs to install the Aubetechs yet, but he's started the wiring. All in all, it looks like our adventure with HRV installation is slowly drawing to a successful, if not entirely satisfactory (from an aesthetic standpoint) close. In a future post, I'll give a retrospective.

The Last of the Drywall Removal

2010-12-15T20:53:00.000-08:00

We are hopefully finally, finally done with drywall removal. Due to a screwup by The Project Manager Who Shall Not Be Named, the original drywall removal effort failed to remove drywall from 4 different areas on the thermal envelope. Two of those were small enough that they could be removed without calling the drywall removal contractor back, but the other two were not. One was fairly obvious, it was the back wall of the southeast upstairs bedroom (Bedroom3), and we called the drywall removal contractor back to do that in September. But the last area was a 4' wide section on the southeast wall of the main hallway that Christine caught when she was in the house a couple weeks ago. We had it removed this week:

Our house has lots of small wall runs along the thermal envelope like this one. While they give the house a kind of quirky aesthetic (actually, one reason why the house appealed to us in the first place), they do increase the surface area for heat leakage and complicate insulation. If the house were just one big, four walled box sealing it would be simple but it would be less interesting from an architectural standpoint. Proper air sealing becomes even more important for these small runs, and especially the joints between the short runs and the rest of the wall. You can be sure I will be looking for that when I do the inspection after the insulation contractor is finished.

PG&E and Electric Car Chargers

2010-12-11T12:40:00.000-08:00

If you recall, we applied to PG&E for a 200 amp service upgrade at the beginning of November (we currently have 100 amps). The request has been grinding its way through PG&E's process. A few weeks ago, we informed them that we would be getting an electric car next year. This week, The Lovely Wife got a call from a Glenn, from PG&E. He asked to speak with me. Because he called TLW on her cellphone, I wasn't there. But he never called me back. On Thurs. at our weekly project meeting, Paul told me that he had spoken with Glenn (I guess he thought Paul was me) and what PG&E wanted. What they wanted was to know whether we wanted a second meter for the electric car.

I was puzzled. Why would we want a second meter? Paul said that PG&E wanted us to charge the car at night, to avoid overloading their transformer and the circuits that supply our neighborhood. The claim is that an electric car establishes a load equivalent to another house. The charger draws maximum 40 amps at 240V (but most likely less than that, since breakers are typically overprovisioned). That's 4.8 kw, a pretty hefty sum, and that over 6 hours, for a total of 28.8 kwh. If I'm the only person in the neighborhood charging, then there is probably no problem. But if electric cars catch on, PG&E is in trouble. They will quickly run out of overprovisioned capacity and need to start upgrading their transformers and other "last mile" circuits. As we know from the telcom world, utilities hate to upgrade "last mile" infrastructure because there is a lot of it and therefore upgrading is expensive.

I don't think PG&E has much to worry about, personally. I suspect my neighbors with houses built in the 70's like mine (some were built later) all have a 100 amp mains feed like ours does. In our neighborhood, the mains feeds are underground rather than coming from a pole, which makes the neighborhood look nicer but makes upgrading a real challenge. Rather than simply restringing a wire, PG&E needs to bring in a backhoe, dig up the conduit, and replace the 100 amp line with one that will handle 200 amps. Backhoe work is expensive and PG&E's process is time consuming. I can't see any of my neighbors going through that kind of grief, unless gas gets up to $6.00 a gallon. Then maybe even the two neighbors across the street with two SUVs each might have second throughts.

Anyway, I pondered briefly if we did want a second meter for the electric car charger. PG&E offers a special tariff for electric car charging service, called E-9. The cost works out to around $0.06/kwh at night and $0.30/kwh during the day. So there is a real financial incentive not to charge during the day when more power is being used by businesses and residences. But we are already on a time of use tariff, E-7W, for our solar PV. This has the same kind of incentive: $0.09/kwh at night most of the year and $0.30/kwh during the afternoon in summer (the winter rates are much less). The rate on summer afternoons is high because PG&E needs the power for all the air conditioners in the Central Valley. We can save big time by not using power then and banking the credits for the winter, when our solar panels get little sun and the folks in the Central Valley have their gas heaters cranked up instead of their air conditioners.

But the $0.03/kwh differential in price caused me to haul out my calculator. Would we save by taking a second meter an the E-9 rate? Our new solar PV system has 2000 kwh/year capacity designed in for the Nissan Leaf. This amounts to around 8000 mi/yr, the amount we usually drive our around town car, at 0.25 kwh/mi, the amount of energy a reasonably aerodynamically efficient electric car uses. Since we cannot connect up the solar PV system to more than one meter, the generated power would not offset the power we use for the electric car on the second meter. Instead, PG&E would reimburse us for it, which they will start doing next year. The rate we get is paltry, $0.08/kwh, even for the expensive power we generate in summer (this is a ripoff in my opinion, but that's the subject of another post).

We would end up paying $120/yr for power on the E-9 rate and getting back $160/yr for the solar power we sell to PG&E on the main meter, for a grand total of $40 to our credit, enough for a nice lunch for two at a fancy Palo Alto restaurant. Looks good, right? Think again! PG&E also charges you $75/yr for renting the meter. So we would end up paying $35 more with a second meter than with a single meter. And, in addition, we would be constrained to always having to charge at night, even if we occasionally need to charge in the afternoon on a weekend because we have taken the car somewhere (this happens sometimes with our current plug-in hybrid). So our answer to PG&E is a polite: "Thanks but no thanks."

According to PG&E's online schedule, the 200 amp upgrade begins Dec. 24. Think of that: PG&E as Santa Claus!

More on MPP Balancing v.s. Microinverters

2010-12-10T20:48:00.000-08:00

IEEE Spectrum has a short article this month discussing MPP balancers v.s. microinverters for optimizing power from solar PV systems. If you recall, in this post, I discussed the reasoning behind my decision to go with Tigo's MPP balancer solution v.s. a microinverter solution such as Enphase. Suprisingly (at least to me) the author of the article confirmed the reasoning. The author found the MPP balancers, in particular Tigo, better than microinverters because the electronics are simpler and cheaper and there are no electrolytic capacitors to fail. The complicated part is not up on the roof, it is down next to the inverter doing calculations, so it is much easier to replace. REC Solar (the company we are having install our system) tried out both microinverters and MPP balancers at its corporate headquarters for a year before going with Tigo, something we in Silicon Valley call "eating your own dog food."

The REC sales guy also mentioned something about an infrared picture of a system with a microinverter where the microinverter was in the center of a huge red area of high temperature. I searched a bit but couldn't find it. I found a forum where there was some discussion of microinverters v.s. MPP balancers. The claim from the microinverter faction is that microinverters are mounted on the panel racking and therefore don't touch the panels, but even so, they increase the temperature by around 6F. That shouldn't be enough to cause major problems if properly installed, but a slight bit off and the panel could get cooked. Temperature increase was another one of my concerns. It can cause premature panel aging and will in any case reduce the amount of power produced by the panel. MPP balancers use DC-DC conversion to maintain the voltage at an optimal level for maximum power output. This results in less heat loss near the panel, though, of course, the centralized inverter still is not 100% efficient so the inverter can heat up. But it is easier to put the inverter in a shaded area, or an area with some wind to dissipate the heat.

Really, the only advantage I can see of microinverters is that they can be installed by someone with essentially no training, except in standard AC wiring. MPP balancers require training to install. This of course makes the labor cheaper, but - the professionalism of American construction technicians being in general what it is - you get what you pay for. If the guy installing it decides, hey, why not just clip the microinverter to the panel nobody will notice, it will end up prematurely aging the panel. Then they get to come back and replace it, for a fee. We've had plenty of experience on this job with that kind of reasoning.

I also discovered I need a CAT5 cable from the monitoring box to where my DSL router is located (technically it is a DSL modem cabled to a Linksys router, I have an older model modem). Luckily, the walls are completely open, since the electrician will need to run the cable through the walls from the front of the garage to around the middle of the house on the second floor, where our home office is and where we keep the DSL modem. I asked Tigo about a WiFi wireless bridge. These devices are not access points, but act like a wire without the copper. Tigo discouraged me from using one. They claimed that the wireless bridges often go down and then they need to call up the homeowner and ask them to reboot it. The Tigo box sends measurements to the Internet every 10 minutes, and can buffer up to 2 days worth of data. Tigo monitors the condition of the panels and I guess lets the homeowner know if there is some problem.

I think the assumption behind the wireless bridge manufacturers is that they will be used in an office setting and therefore someone will notice if they go down because YouTube isn't coming up. Then somebody will reboot the bridge. For machine to machine communications, though, the reliability must be much higher, otherwise, you end up with an expensive "truck roll equivalent" in which some person must find the box (could be difficult if it is in an out of the way place) and reboot it. Perhaps wireless links are better for control systems, where a person is dialing temperature up or down or setting a timer on a fan. In that case, if the wireless link is faulty, it should show up on the remote and the person operating it can take some action, like replace the batteries in the remote.

So we'll go with the CAT5 cable, and, in addition, get another from the solar hot water tank so that we can at some point put Internet data recording for that too. With data on both, I can get a much better picture of how much of the house's energy is coming from our renewable energy systems.

More on Optimal Solar Thermal Backup

2010-12-05T19:23:00.000-08:00

If you recall, in this post, I discussed why we chose an electric on-demand hot water heater for backup to our solar thermal hot water system. The conclusion was that electric on-demand was best because:

On-demand allows the solar hot water to contribute the maximum amount of energy. If you have a tank-based backup, either integrated with the solar hot water tank or in a separate tank, the backup energy source will come on whenever the tank goes below 120F and will heat the whole tank, whereas the on-demand heater only comes on to heat the water you need.
Electric on-demand is better than gas on-demand because the electricity can be directly offset by installing more solar PV. But even if you don't consider the offset, electricity is better because the electric grid is incorporating fossil carbon-free energy sources faster than the gas grid.
Gas on-demand requires complex venting whereas electric on-demand is just another appliance you can fasten to the wall in a closet (which is what we are doing).

An article in the most recent edition of Solar Today goes into much more detail about the optimal backup for a solar thermal hot water system. The criteria in the article are somewhat different, emphasizing seamless transitioning between solar thermal and backup. We are not so picky, we turn off the backup in summer and on again in late fall, so if we get any clouds in the summer we may end up with a day of warm water. But the article confirms that on-demand is better than tank backup, for the same reason as I concluded, and that electric on-demand is better than gas. The author goes into much more detail about why electric is better than gas, but it boils down to the lack of real modulating capability in gas on-demand and the need for a larger draw of water volume (0.5 gps v.s. 0.25 gps for electric) before the gas on-demand unit kicks in.

On the downside, electric on-demand units draw an enormous amount of current. Our unit has 3 220V/20 amp heating units. When all units are active, it will draw more current than the hot tub does. The utilities don't like that kind of draw because it causes transformers to heat up, and can cause lights to flicker in the house, especially if there is more than one on-demand heater active in a neighborhood at a time. You need to have a 200 amp residential service in order to install one, we have a 200 amp service upgrade on order from PG&E.

But the utilities are going to have to upgrade their transformers and circuits for electric cars anyway. Gas on-demand units also require a large (1" I think) gas main, which many residences don't have, so even with gas-on demand you may need a residential service upgrade from the utility. And, for solar backup, the on-demand heater must only heat the water from 80F to 120F, not from 60F which is the usual water main temperature here in winter (our solar hot water tank is now around 80F due to cloudy weather), so it is less likely that, in our case, all three heating units will fire at once. All things considered, electric on-demand seems to be a better option for solar thermal backup.

HRV Problems

2010-11-28T20:22:00.000-08:00

The HRV system was finally "completely" installed, by Duke's HVAC. Here's what I discovered on the back of the house one day a couple weeks ago when I got home from work:

The upper hood in the middle is the existing high speed bathroom ventilation. The ones on the lower left and right were meant to be the HRV intake and exhaust. Fantek customer support recommends that, on the same plane, the intake and exhaust vents should be at least 6 feet apart, and that the intake should be at least 6 feet from any other exhaust including attic vents. The maximum distance in this case is 3 feet between the bottom two vents, and 1.5 feet between the bottom two and the middle one.

When I complained to Paul, he asked where I wanted them. I considered what would be the easiest thing to do. There's very little room on the wall in the chase upstairs. The diagonal distance between the lower right hood on the picture and the upper left corner where the wall runs is maybe 5 1/2 feet. So I said why not put the intake on the roof, thinking perhaps it would have a longer pipe like a chimney.

Here is what we got:

The intake is so short it will draw in fumes from the asphalt shingles when they heat up.

I remeasured everything this morning but there is simply no way we can get 6 feet between the HRV exhaust, bathroom exhaust, an attic vent, and the HRV intake. It seems fairly clear that the bathroom exhaust needs to go out the roof vent, since it will be fairly strong. I also think the HRV exhaust will need to go through the roof, since I don't see any place where we can put it on the wall. The attic vent can stay on the right lower side of the back house wall in the picture above. That leaves the HRV intake. We could run a duct into the bedroom and out the bedroom wall, extending the chase we put in for the duct that runs to the hall. The extension would be below the wooden frame in this photo:

The vent would then run out the wall on the right side. Or we could simply put the duct at the upper corner of the attic area even though it is around 6" short. That might not be such a problem, since the attic vent won't be forcing air out like the exhaust. The hood will direct it downward and the intake will be much higher on the wall.

The front HRV is in better condition. There, I asked our good friend Duke to direct the intake through an existing attic vent in order to reduce the number of vents on the front of the house, but Fantek customer support tells me there needs to be a separate 6" hooded vent for the pressure to work. So we can just move the exhaust to the bottom below the attic vent, and put the intake where the exhaust is now. That way, the exhaust will not re-enter the house through the attic vent, and there is at least 8' between these vents and the intake.

One thing is for certain, though. You would have thought our good friend Duke would have given Fantek technical support a call before he started hacking around on the back side of our house. I'm certain at least one and possibly two of the holes need to be patched, either in place or by replacing the siding and cutting new holes.

The other problem is that I have an ominous feeling about the noise the HRV will generate. On Monday, I was working at home and several times a rumbling noise started up above my head. I think this was probably our good friend Duke starting up the HRV unit. I tried it again today and it was nowhere near as quiet as the unit Paul showed us at another job he did, when we were trying to decide if we wanted to put in HRV. Paul showed us an HRV installation he had done himself, in which the unit was hung from wires. No vibrations are transferred to the building structure. Running fully on, the HRV was absolutely quiet, and we requested that our unit be mounted similarly. But when I got home from a conference in Washington earlier this month, I found that our good friend Duke had used heavy metal bars to fasten this one down, though there were a couple of shock absorbers and some missing rubber gaskets which supposedly would cut down on the vibrations. He installed the rubber gaskets on Monday but if what I heard on Monday was the HRV, there still might be vibrations transferred to the house frame.

Thermal Bridging

2010-11-24T21:20:00.000-08:00

I've done some research on limiting thermal bridging. 25-27% of the interior surface in a typical stick-built building in the US consists of the face of the studs, headers, and other structural elements that extend through the walls from the inside to the outside. Our exterior sheathing is really simple due to the fact that the house was build in the 1970's before people understood about these things: one layer of plywood on the outside and tarpaper on the inside of the plywood to reduce moisture contact from rain and condensation. So the studs extend between the exterior sheathing and the interior drywall, acting as a major thermal bridge. Thermal bridging reduces the R-value of the walls by a considerable amount. A 2x4 stud is around R-4 while a 2x6 is around R-6. Even if the cavities between the studs are insulated with R-6/inch closed cell foam (for a cavity R-value of R-21 for a 2x4 wall or R-33 for a 2x6 wall), the impact on the wall assembly is a reduction in R-value of around 33%. For example, an R-19 insulated wall is reduced to R-12.8 by thermal bridging. Condensation on the interior surface of the studs and mold growth is a possibility. In fact, we found some minor mold growth on the interior studs of the back hallway wall. This wall gets no sun in winter at all, so it is possible that some condensation occurred during an especially cold winter night and never dried out the next day.

Thermal bridging is most evident in thermal imaging pictures. Consider this image taken of the master bedroom wall (unfortunately not being re-insulated at this time since we are living in it):

If you are interested in major problems, the bright blue along the corners where the walls and ceiling meet obviously draws the eye. These are places where the fiberglass batt insulation was improperly installed or has sagged with age (it is the former in this case, we had this room remodeled only 4 years ago). Major thermal leaks are occurring. But the thermal bridging effects of the studs can be seen in the dirty blue lines extending downward from the ceiling. These are the thermal traces of the studs. Reinsulating the wall with closed cell foam will get rid of the bright blue along the corners, but not the dirty blue below.

One very nice solution to thermal bridging is a product called Thermablok. The product is 4'x1.5"x0.4" strips of aerogel. The strips have a sticky side like tape, and are designed so that the backing can be removed and the strips simply stuck to the face of the studs. Aerogel is the best insulating material known, R-10 per inch, short of full vacuum. The R-value for a Thermablok strip is around R-4, effectively doubling the insulating power of a 2x4 stud. The cost is $1/linear foot or $4/strip, on the expensive side compared to materials like fiberglass batt or even spray foam.

I looked into Thermablok as a possible solution to thermal bridging in our house. A couple years ago, I made a thermal model of our house which required measuring all the walls. It is not perfectly accurate, but I think it gives a good estimate. The estimate of the area for the currently removed thermal envelope is 2520 sq. ft. At 25% stud area, the amount of stud area is 630 sq. ft. This would require 1261 4'x1.5" Thermablok strips, which, at $1/linear foot would be $5041, in addition to the labor to install it. And this price does not include the studs under the floor. This is pretty expensive. Besides that, as Paul mentioned when I brought up the topic in one of our meetings, rigid spray foam is rarely flush with the face of the studs, so there would be additional bridging through the rims of the studs that are exposed above the foam.

In an effort to find a cheaper solution, I googled around a bit for some more information. I found this reference which describes how to handle thermal bridging with normal insulating materials. Ideally, the external walls should be sheathed with extruded polystyrene board on the outside, but of course we can't do that. The recommendations that we could follow are:

On the ceilings, 2" foil-faced rigid polyisocyanate board as sheathing on the inside held in place with 1x4 furring strips, 16" on centers
On walls if you can't use exterior sheathing , 1" polystyrene board (XPS) held in place with 1x4 furring strips, but I think maybe polyisocyanate could be used there too since I think it is a greener material than polystyrene and has a slightly higher R-value.

In addition, the gaps between the rigid boards must be sealed, and special attention must be paid to the headers and footers. The link above has a couple of points about thermal bridging around headers and footers, and I've seen some about window sills, but mostly these seem to be for new construction, since they involve installing insulation between the structural members before they are fastened together. Buildingsciences.com also has some papers on thermal bridging too, but no dedicated reference and mostly it is about new construction.

The reference above doesn't mention under the floor, but I think we get thermal bridging through the floor too. So the same treatment as for the ceilings would probably be appropriate though it might be possible to use thinner strips to hold the rigid board in place and a 1"polyiso would be sufficient, since the crawlspace is already pretty tight and heat loss downwards isn't as serious as heat loss upwards.

I think the HRV chase upstairs would need a different treatment, because there simply isn't any space to get polyiso board in, besides which, it might crack and come loose when trying to crawl back into the space, for example, to service the HRV unit. I think that area could be done with Thermablok since it is relatively small. The area is around 38 sq. ft. and it would be about $76 for Thermablok. So I think it should be possible to install the Thermablok by hand and use some touch-up foam along the studs where the spray foam didn't cover to the top of the stud.

We also opened up an area from the outside under the living room window where we could do exterior sheathing. There is a large, exposed footer that will act as a major thermal bridge. I don't know if enough clearance exists for 1" rigid board, though, since the window assembly is already in place. Thermablok could probably be used in this area, since the amount would be relatively small. Since Thermablok is only 0.4" think, there should be less problem with clearance.

Unfortunately, we can't do anything about the footers and headers from the outside in the rest of the house because the siding is in place. We can mitigate bridging through the headers from the inside somewhat by ensuring the rigid board is sealed along the headers, and that gaps are filled with touchup foam, but we can't do anything about the footers because the floor is in place. We also can't do the wall between the garage/attic and hallway/kitchen because we had that redone several years ago and I was primarily interested at that point in simply reducing air infiltration to improve air quality, and not in reducing heat loss to the maximum extent possible.

Eliminating thermal bridging is one of the treatments necessary to build according to the German Passivhaus standard. The Passivhaus standard aims to get away with really minimal additional active heating and cooling, and uses HRV quite extensively. We are never going to turn our house into a Passivhaus, but I thought we could learn from what they do and try to get our carbon footprint down even further. So it was with visions of reducing our carbon footprint from heating by 50% instead of 30% dancing in my head that I emailed Paul with the above suggestions for eliminating thermal bridging in our job.

Unfortunately, The Lovely Wife brought those visions crashing down. Already annoyed by the length of time the job is taking and my tendency to want to make things right, she pointed out that the insulation contractors who Paul was soliciting for bids had probably never done thermal bridging elimination before. And the drywall contractors probably hadn't dealt with trying to fasten drywall when the walls were sheathed in polystyrene board. Considering the fact that our HRV contractor screwed up some fairly simple aspects of the installation which he could have had right by calling the manufacturer's technical support (see forthcoming post), the probability that the insulation contractor and drywall contractor would completely screw up any thermal bridging treatment was very high. In addition, all the electrical outlets are already in place, so if we put in 1" polystyrene sheathing, they would need to either be moved outward or extended somehow, to say nothing of the places were the drywall was not removed.

Sadly, I sent another email to Paul and told him to forget about the thermal bridging treatment, except on the back wall of the hallway. The mold indicates a major problem, so we'll confine the treatment to just that wall. Because it is such a limited space, Thermablok to cover it should not be so expensive, and any areas where the spray in foam failed to cover the stud can be touched up by hand with can foam.

Solar PV Design

2010-11-20T16:51:00.000-08:00

The process of finalizing a design and a contract with a solar installer took an incredible three months. We've decided to go with REC Solar since their preliminary bid came the closest to what we wanted. We started the process in early August when I sent a rough description of the system to Forrest, our architect, and The Project Manager Who Shall Not Be Named. TPMWSNBN subsequently quit (or was gently fired, not sure which), but he hadn't done anything to start the process rolling anyway. Around the end of August, Christine put out the contract for bids. I had thought that TPMWSNBN had conveyed to her what I wanted but, after the bids came back, we realized that was not the case. As previously reported, one bid came from a roofer "wanting to get into solar installation" (we declined to pay for his training), one came from a nonprofit that sends volunteers up on your roof to install the system (our roof is quite steep and a professional roofer fell off when we had it replace in 2003, broke his collarbone, and required 3 operations), and a professional solar installer. Not surprisingly, the professional solar installer came closest to what we wanted, but it was not quite right. So we started the process over again sometime around the end of Sept.

One of the problems we have is that our job is not the typical situation that most solar installers face. Most people who get solar don't have any in the first place, and so the solar installer can take a year's worth of PG&E electrical usage data and come up with a good estimate about how the homeowner can eliminate 80% of their PG&E bill by installing solar. At which point, the homeowner is thrilled because the estimate shows them paying PG&E far less. In our case, we already have a solar PV system, so our bill tells the installer little about our electrical use. We still draw about 2000 kwh from the gird, but we pay nothing for that power because PG&E credits us around 3x for power generated on summer afternoons what we pay for power at night, when we are recharging our converted plug-in Prius, and in the winter, when we have lots of lights on and the furnace runs. We never use up the surplus credit, though we have been coming closer since we converted our 2008 Prius to a plug-in hybrid. We also are also primarily interested in completely offsetting the carbon footprint from our electricity usage, not in eliminating or reducing our electric bill, though of course that should follow if we completely offset the electricity usage.

In addition, we are having some new electric appliances installed, and are planning on buying a Nissan Leaf electric car next year. So we need somehow to plan a system that will offset our current grid draw and, in addition, offset the usage from the new appliances and the electric car if we want to eliminate our carbon footprint. Estimating the usage from the appliances is straightforward, but with the car, the electrical usage is likely to be somewhat more unpredictable. However, I came up with the following projected usage requiring offset in addition to the power provided by our current 2.5 kw system:

2000 kwh/year - current grid draw
360 kwh/year - HRV system used for 6 months in winter when the windows are closed, 24 hours per day
633 kwh/year - on-demand electric backup hot water heater. This was calculated by using the historical energy use from our gas-fired hot water heater, correcting for the (in)efficiency of gas-fired tank hot water heaters, and assuming that the backup heater would be needed for 6 months in winter.
2000 kwh/year - Nissan Leaf charging. This was calculated assuming 8,000 miles per year at 0.25 kwh/mile. We typically drive our commuter/around-town car about 8,000 miles per year and 0.25 kwh/mile is a standard figure that a reasonably aerodynamic electric car should achieve (it is slightly more than what Nissan assumes, since the Leaf has a 24 kwh battery and is supposed to get around 100 miles on a charge).

The total additional grid draw beyond what our current 2.5 kw system supplies: 4993 kwh/year, or around 5000 kwh/year.

My original plan was to add a 30% margin to that to allow for power usage growth in the future. For example, if we revisit the decision not to install a geothermal heat pump, or even maybe go for an air source heat pump, we would then remain carbon neutral without having to install new panels. However, I found out near the end of the design process that PG&E won't allow solar installers to put in more panels than will completely offset the homeowner's electricity use, without good reason. Theoretically, this would not have allowed us to offset the new appliances or the Nissan Leaf because they weren't on our bill last year. REC and the other companies bidding on the contract kept sending bids for 18 panels, or 26 panels, until finally the REC engineer explained the problem. When I told them about our situation, the REC engineer accepted my explanation - that we were buying an electric car - as sufficient justification for a larger system. However, they would not let me include a 30% margin. This is unfortunate, because I was planning to offset the carbon generated by our gas hydronic furnace, gas stove, and new gas fireplace from the portion of the 30% margin that we didn't use. I guess we will just have to continue to buy carbon credits for that, as we are doing right now.

I also originally requested Sunpower E19 modules which generate 315 watts/panel, thinking that more watts per panel would reduce the number of panels and therefore the amount of space on my roof taken up by the PV system. However, Christine pointed out that the E19 was actually larger than standard modules, around 10" wider, though the same length. So, in effect, we would end up using about the same amount of roof space with the E19 as with a set of standard panels that generate 235 watts/panel, the maximum currently available in a standard-sized residential panel. REC also advised not to go with Sunpower, since they are a name brand and they charge extra for the brand. They instead recommended the Kyocera 235 watt module, the KD235GX-LFB. This model produces exactly the same amount of power as the Sunpower E18 series (which is standard sized) but is cheaper.

My original calculations, including the 30% margin, came up with a total system size of 6.85 kw DC. However, I failed to account for shading and losses due to AC conversion. When REC calculated the size of the system, it was 7.050 kw DC without the 30% margin. In either case, the number of panels is 30. As a practical matter, this is probably the maximum amount we can fit on the part of our roof that gets sufficient sun year round. You can see the problem in the picture below, which was screen-copied from the satellite photo of our roof from Google Maps (taken before the solar thermal system was installed on the east roof):

On the south end of the house (lower part of the picture) there is a huge hedge of redwoods in our neighbor's yard. These shade the south end of the house all year round. While we are certainly grateful for this shade in the hot California summer, in the winter, there is not enough sun on the south end for solar. So the entire array must be installed on the north end, on the west side roof - where you can see our 18 panel array today - and on the east side roof. REC is proposing to put 20 panels on the west side and 10 on the east side. This maximizes the number of panels that are exposed to sun during summer afternoons, when the net metering tariff is high. As a practical matter, 20 is probably the maximum that could be fit on the west side, due to the skylights and the solar-powered attic fan.

The next decision we needed to make was about inverters. An inverter changes the electric current from DC to 60 Hz AC (usually around 440 volts), which is compatible with the grid. The conversion process is relatively inefficient, losing around 12-15%, which is why REC's design calls for more DC power than my initial estimate. Our old system has a centralized inverter that sits on the side of our house, here you can see it:

When we had the old system installed, centralized inverters were the only technology available. Centralized inverters require the solar panels in each row to be wired up in series. The output side of one panel is connected to the input side of another and the entire system is then manually balanced so that the voltage seen by the inverter is the same for each row. The problem with this design is that shading, dirt, and irregular aging of the panels can cause the voltage from one or two panels in a string to drop, either transiently or permanently. Like a string of Christmas tree lights in which if one light goes out, they all go out, the entire string of panels is then cut out and the system loses power from all the panels in the string. The result is that the system can lose somewhere around 15-20% of total power output during a shading incident or permanently if the problem is due to irregular aging.

Recently, new technology has been developed to alleviate this problem. There are two different approaches:

Microinverters - rather than having a centralized inverter, each panel has a separate microinverter on the panel and the electricity coming off the panel is AC instead of DC,
Maximum Power Point (MPP) balancing - the electricity coming off the panels is still DC, but a control unit on the panels adjusts the voltage and current so that the inverter always sees the right combination to maximize power from the array.

Microinverters were pioneered by Enphase. The advantage of microinverters, in addition to the increased performance, is that they make installation of a solar PV systems exactly like installing any other home appliance, for example HVAC or a refrigerator. The installer simply plugs the panels in parallel into an AC bus and runs that into the grid with a cutoff switch. No need to understand the special needs of high voltage DC wiring. But a problem with microinverters is that, like centralized inverters, they use electrolytic capacitors. Electrolytic capacitors contain a fluid that over time evaporates, which makes their lifetime considerably less than that of the solar panels to which the microinverters are attached. Microinverters with electrolytic capacitors have a warranty of 15 years, same as centralized inverters, whereas panels typically have a warranty of 25 years. If the inverter fails before the panel, the panel must be removed and the inverter replaced. When a centralized inverter on the side of the house is replaced, nobody has to crawl around on the roof and remove a heavy panel to replace the inverter. Solar Bridge, a newer company, has announced microinverters with film capacitors having a warranty for 25 years, but their product is not yet available.

MPP balancing systems use a centralized inverter, but each panel has a small control unit on it that measures the voltage and current. The control unit constantly adjusts the voltage and current so that the inverter sees exactly the right combination to maximize the energy generated by the system. The MPP balancing system can also determine whether the panel is experiencing accelerated aging or otherwise needs replacing, and report this through a Web interface (microinverters have this ability too). The capacitors in the control unit don't have to be very large and therefore don't need to be electrolytic. So MPP balancing systems typically have a longer warranty, usually 20 years. Still not the same as panels, but better.

When I was originally considering 315 watt panels, I discovered that nobody made a microinverter which handled more than 230 watts per panel, so I requested an MPP balancing system. Residental MPP balancing systems are not parametrized by the panel power rating but only depend on what the centralized inverter can handle. Tigo is one manufacturer of MPP balancing systems. Because MPP balancing systems are used more in large, commercial PV installations where ease of installation by relatively untrained personnel is not an issue, very few residential installers have much experience with them, so they either won't bid them or they have lots of reasons why such systems aren't as good as microinverters. I requested that Christine call up Tigo and another MPP balancing manufacturer and ask them for recommendations about solar installers that know how to install MPP systems.

After I found out about the increased panel size for the 315 watt panels and decided to go with the smaller 235 watt panels, I briefly considered switching to microinverters. But in addition to the issue of the short warranty, microinverters may have a thermal problem. The temperature under a solar panel in the summer is usually very high, maybe well above 100F. The inversion process itself generates heat, and the electronics become more inefficient as the temperature rises. Since a centralized inverter can be positioned where it is in the shade (as it is on our house), a lower temperature can be maintained. MPP balancing systems therefore have the potential to be more efficient in summer, when the PV system is generating the most energy. Because they don't handle such large amounts of electricity, they don't generate as much heat from the electronics. As a result, I requested that we stick with an MPP balancing system. REC has experience installing Tigo MPP balancing systems, which is another reason why we selected them.

REC's final projection was that the system would offset 101.65% of our electricity use and 90.04% of our bill. It's impossible to offset 100% of the bill because PG&E charges around $7/month for the privilege of connecting up to their system. Here's a table of REC's projections about our power use, solar production, current (actually projected) utility cost without solar, and projected utility cost with solar:

The chart shows that we only need to pay for electricity in January and February. In the other months, only PG&E's connect charge appears. The calculation isn't strictly accurate because the estimated usage is the same for each month. Since we'll only be using the on-demand hot water heater and HRV from October through March, the usage for those months should be higher, while the usage for the months April through September should be correspondingly lower. I recalculated the estimated usage and estimated utility charge with solar and came up with the following table:

My assumptions were:

The 993 kwh/year usage from the HRV and the backup hot water heater were removed from the summer months and distributed evenly over the winter months,
The 165.5 kwh/month thereby gained in the summer months were sold to PG&E for $0.28/kwh, the summer afternoon net meter tariff,
The 165.5 kwh/month used in the winter were bought from PG&E for $0.10/kwh, slightly higher than the current PG&E winter tariff.

These assumptions are likely very conservative, but to first order they nevertheless show us with a $35.42 credit at the end of the year. We could either use that up by running our electric floor heater in the solarium or we could get credit back from PG&E for the power (though they don't pay much).

Holes

2010-11-13T12:03:00.000-08:00

Work seems to be progressing but mostly in the design space at the moment. The electrician finished up the low voltage wiring and all but one of the new 110V circuits. We have settled on a solar contractor and a rough set of specifications for the solar PV. The contractor is now working on a specific design and a bid. We have requested that the contractor have on-site at all times someone who has worked for the firm for at least one year, so we don't get burned again by an incompetent employee that was hired a few months ago. The insulation bids that were solicited by The Project Manager Who Shall Not Be Named were, as with most of the work he did, inadequate and Paul is re-soliciting based on my feedback. Our 200 amp upgrade request is in with PG&E and we are trying to find out the schedule. Projected completion is beginning of Feburary, but I believe that may stretch out depending on the solar PV installation schedule. But best of all: The Lovely Wife seems to be happy with progress!

I had a moment of concern that the extra 100 amps for our grid connect might not be enough after I found out that the on-demand hot water heater has three heating units, each of which requires 220V/40 amps. That is an enormous amount of power, 8.8 kilowatts, but applied over a very short period of time, maximum 20 minutes for a shower, so the net energy used is less, about 3 kilowatt-hours. The electric car charger only requires one 220V/40 amp circuit, but charges over a period of 6 hours. I did a rough calculation assuming a 440V/100 amp upgrade to the existing grid feed (440V/100 amps), which seems to be fine for our current set of appliances, and it should hand the on-demand water heater, electric car charger, and HRV (the HRV is peanuts, maybe 40 watts maximum).

I also did a short tour of the gutted interior looking for holes. One "feature" of older houses such as ours is the shoddy sealing of exterior penetrations. Here is an example:

The thin white line you see on the left side of the picture is a 1/4" to 1/2" gap between the dormer flashing and the building frame in the upstairs bathroom. This gap acts as a conduit for warm air to leak out of the building in winter. The fiberglass batt insulation that was in the stud bays here is completely inadequate to stop such leakage.

Gaps also occur between the interior wall space and the living space, as in this picture:

This picture was taken in the upstairs bathroom where the drywall was removed between the raised downstairs bathroom ceiling and the upstairs bathroom wall. The gray area is the back of the drywall on the light tray above the shower and toilet compartment doors in the downstairs bathroom. The white dust is plaster from drilling when the HRV vent was installed. The thin white line at the bottom is a 1/4" gap where the contractor failed to tape the drywall. This gap now acts as a conduit for smelly air from the bulk of the house to leak into the bathroom when the bathroom ventilation is on.

Another gap has even more serious effects:

I crawled into the unfinished attic next to the southeast bedroom upstairs where the HRV is now located. This picture was taken at the far end, where the uninsulated bathroom wall terminates the space. What you are looking at in the center of the photo is a large gap under the bedroom floor where the old forced air duct plunges under the floor toward the mechanical room where the old forced air furnace was located. The whitish yellow blob is insulation on the forced air duct. To the left of the gap, the space between the unfinished attic and the floor under the upstairs bedroom (which is over the ceiling of the master bedroom downstairs) is blocked off by a floor joist. But the gap for the forced air duct is completely open, and explains why, on summer nights, the downstairs master bedroom smelled like someone's old hiking boots. We had a pocket door installed in the master bedroom a few years ago. The interior of the pocket door is open into the wall cavity and not sealed. So on summer afternoons, when the upstairs unfinished attic is shaded and cool but the downstairs bedroom is warm, cool smelly air from the unfinished attic enters into the wall through this gap and out the pocket door enclosure.

Here's a gap that is not quite a hole:

This is between the fiberglass window frame and the wood frame of the house. There is no insulation here although the space is sealed on the outside, but this gap acts as a thermal wire, allowing warmth to escape from the house in winter.

The disturbing aspect of these last two examples is that they are in areas where we had contractors work in the 7 years since we owned the house. They are not from the original framing or from work done by previous owners. You would think that, in the 21st century, contractors would have some clue about building science and make sure that the work was up to the latest knowledge at best quality. But most contractors are clueless about how to properly insulate a building. They are still working with knowledge they gained in the 70's when they started working.

Finally, and example of the attitude toward proper insulation in the 70's when our house was built:

This picture was taken from outside the house, looking into the cavity under the tiled shelf under the living room windows. What you see here is a chunk of fiberglass insulation on the right side and the end of a chunk on the left (obscured by the wood frame). In the middle, is a huge gap, 4-6" wide, where an electrical wire runs and the drywall is visible. It is no wonder the tiles in the living room are icy cold in winter.

The picture is a perfect example of the attitude about proper thermal sealing in California in the the 1970's. It seems to be: "oh, California is such a mild climate and gas is cheap. Let's throw in a couple pieces of insulation here and there to say we did it. No need to do a through job". We saw exactly the same kind of shoddy insulation above our kitchen ceiling when we had a sun tunnel installed a couple years ago.

This example is why I disagree with people such as Matt Golden at Recurve, who claims that there is lots of "low hanging fruit" in energy efficiency. The number of houses that have no insulation at all and can be reinsulated at relatively low cost by drilling through the drywall and injecting blown in cellulose is far exceeded by the number with shoddly installed fiberglass batt insulation like ours. Most houses with no insulation were built before 1970 and there are far fewer of those than were built between, say, 1970 and 1995 or so with shoddily installed insulation. The cost and hassle of reinsulating a house like ours using the existing building technology, as we are finding out, far exceeds what most people are willing to go through.

HRV, On-Demand Water Heater, and More!

2010-11-07T18:04:00.000-08:00

I arrived back home after 2 weeks off-line on vacation last Sunday, and briefly checked out progress on the job. Then I immediately flew to Washington, DC, early the next day for a conference, coming home on Thurs. A lot has been done in the 2 weeks I was gone, more than in the previous 2 months. Today, I finally had time to poke around in more detail. Here's what's been happening.

Mold
Fiberglass batting is not air proof, air can leak through. When our roof was replaced in 2003, the builder did not install any ventilation under the plywood decking as buildingscience.com recommends. Ventilation allows the warm, moist air from inside to vent to the outside, but also of course results in energy loss through the thermal envelope. So in many places, warm indoor air came up against the cold roof decking in winter and condensation accumulated on the plywood. When the water remains more than 24 hours, mold will grow. We had many places on the decking where mold was growing, especially along the ridge in the hallway, since that is the highest spot in the house and is naturally where the hot air accumulates. There were also a couple places on the south side of the house with mold on studs and siding. Since I have a mold allergy (one of the many reasons why we are doing this remodel), I insisted that the mold be removed. We had a mold remediation company come in and treat the mold. The closed cell foam insulation that we are having installed doesn't allow air to penetrate, so it can be sprayed directly on the roof decking and siding to seal against air leakage.

Fireplace
Before we started the remodel, we had in our living room an old pellet stove without any thermostat that needed to be started by hand. I really wanted a newer model with thermostat and automatic starting, but Santa Clara County has a ban on wood burning appliances due to pollution during winter inversions. So we instead opted for a 90% AFUE gas Empire Comfort Mantis fireplace. This is about the most efficient gas fireplace that you can get. It has a condensing firebox that retrieves the heat of condensation from the steam formed by combustion, and takes combustion air from outside rather than within the home. The only downside is that it won't work when the grid is down because the outside venting requires a fan. But neither would a pellet stove, since it requires electricity for ignition and the screw that retrieves the pellet from the hopper.

On Fri., they installed the fireplace. Here's what it looks like without the copper surround:

and here is what the plumbing looks like coming out the back:

One pipe is for the combustion air intake, the other for the combustion gases exhaust. Unlike a lower efficiency furnace/fireplace, the combustion gases are not hot enough to simply float up a chimney and water would also condense out on a metal pipe, so a normal chimney/flue can't be used.

Structural Reinforcement

Another reason why we started this work was because the drywall along the ridge line in the hallway cathedral ceiling was cracking. Not just in small areas, a big gap opened up right along the ridge line from the front bedroom to the middle skylight and it would expand and contract depending on the temperature, raining down little bits of plaster when the temperature rose. Fixing this has turned out to be an enormous problem, and has been responsible for holding up the job for at least a month and a half. We have gone through two structural engineers trying to get some kind of solution that would immobilize the roof enough to prevent future cracking without having to take the roof off and put in new trusses. The basic problem is that the roof beams installed originally were not sturdy enough to support the weight of the skylights and the plywood decking without twisting some. Originally, the roof was wood shake shingles which are lighter, but we replaced it with composite shingles because they last longer, which required the plywood decking. This increased the weight of the roof. But even without the decking, the original roof supports are really not sturdy enough to support the full weight of the skylights - some of our neighbors with the same model house have a similar problem with cracking. It does not mean that the roof will collapse in a major earthquake, just that it is not stable against thermal expansion and minor movement.

The Project Manager Who Shall Not Be Named had the framers install metal plates at the joints but that was insufficient for some of the forces. So the new structural engineer and Paul came up with a series of what look like 10x4's that run up to the ridge beam and transfer some of the load onto the rafters further down:

Here you can see how the beam runs from the skylight, on the left, down along the rafters, on the right, distributing the weight of the skylight more evenly along the roof. The new beams are bolted to the rafters with heavy bolts:

Paul says that the beams will not likely prevent cracking during an earthquake but they will prevent the twisting with temperature and random minor movement which seemed to have caused the original problem.

HRV

The HRV system has been partially installed. We have two HRV units, one in the attic above the garage and one in a chase next to the east side upstairs bedroom. Here's a picture of the one in the chase:

The HRV unit is the Fantek SH704. The hard metal pipe running across above the unit is the existing bathroom ventilation from the downstairs master suite bath. The foil clad soft ducts on the left and the fiberglass clad ducts on the right are the new HRV ducting. The metal bar across the top is the mounting frame for the HRV.

When I first saw the metal bar, I was a bit upset. We had agreed to hang the HRV from wires in order to avoid transferring vibration to the house frame. After all, this unit is right above the master bedroom and next to another bedroom (which we use as The Lovely Wife's sewing studio) . It looked as if they had simply bolted the metal frame to the ceiling rafters and the HRV to the metal frame. However a closer inspection showed that the HRV apparently has a kind of shock absorber on it:

I think a rubber grommet is missing and must be installed yet in the shock absorber. So I'm willing to try it out to see whether or not there is any vibration.

Some details still must be worked out. The attic HRV, on the other side of the house, needs its humidity drain installed somewhere, and I'd like it to go into the new downspout that will be on that side of the house. And the intake and outlet vents on the chase HRV are uncomfortably close, and also close to the master bath venting:

I've asked Paul if we could locate the intake vent further up toward the roof peak where it it is less likely to draw in stale air from one of the exhaust ports. The new chase we installed running from the HRV chase to the hall exhaust vent seems to have enough room that one could run a second duct, depending on how large the duct is. The exterior venting has yet to be determined on the front side for the attic HRV. I've requested that they vent out where the existing attic vent is located, and vent in from the side of the garage. Not sure if they can do this, though, maybe higher on the attic wall would be better.

The interior ducting for the HRV looks like this:

Here the ducting runs in the chase next to the upstairs bedroom. An insulation guy is going to have to climb back in there to insulate the stud bays above the master bedroom and the back of the bathroom wall. It's a tight fit, I climbed back in there myself today. But because the ducts are flexible, you can shove them around, unlike standard forced air ducting. So I think it should be possible.

This next picture shows the chase in the front bedroom closet where the exhaust duct runs from the attic HRV to the exhaust vent in the hallway:

The framer put this chase in so we could run the HRV duct, and a similar one in the east side upstairs bedroom. The attic HRV draws in warm, stale air from the top of the cathedral hallway through the hall vent into this duct and exhaust it, after transferring the heat to fresh, incoming air. The vent cover for the HRV looks like this:

I've requested from Paul if we could get vent covers that look a little less intrusive. White on a colored wall is just too noticeable for my tastes.

On-Demand Electric Hot Water

The framer put in a closet above the upstairs bathroom door for the on-demand hot water heater and also for storage. The Tempra 20 Steibel-Eltron on-demand hot water heater was also installed, though it can't be actually hooked up to the power line until PG&E comes and installs 200 amp service:

Notice the lack of any venting? That is one nice thing about an electric hot water heater as opposed to gas. Because there is no combustion, it doesn't need venting, it's just another electric appliance like the washer or refrigerator. So we can use this closet like any other closet, for storage. It just happens to have a hot water heater in the back.

I checked out how the plumber fitted it into the solar hot water plumbing, and I am not quite sure if I understand. I've asked Paul to check. It should be in series with the solar plumbing, with the hot side of the solar tank running directly up to the on-demand heater, and the hot side of the on-demand heater running to the mixing valve downstairs and then into the domestic supply. This allows the hot water from the solar tank to rise up to the on-demand heater between use, eliminating a gout of cold water that enters the on-demand heater when a hot water tap is turned on, which could cause the on-demand heater to fire for a couple seconds till the flow from the solar tank hits it.

Some people, like Allison here at the energyvanguard.com, don't seem to like on-demand electric hot water heaters. I suppose, if they are not just being used as a backup to a solar thermal hot water system, they could be a problem, since they do use large amounts of electricity, especially if they need to heat the water from 60 degrees F or so to 120 degrees F. But when they are being used as backup, the incoming water is rarely below 100 degrees F and in summer, they won't be used at all. As my previous blog post showed, on-demand electric backup for solar becomes more carbon efficient than gas at some point *if* (and this is a big if) the grid is migrating to non-carbon energy sources. Of course, if you are offsetting the electricity use with home solar PV, as we are planning to do, then on-demand electric backup becomes essentially carbon free. It is also possible to offset a gas on-demand backup with solar PV too, but a gas on-demand heater then requires complex venting.

Next up: PG&E installation of the new 200 amp service, a decision on the solar PV installation and selection of an insulation contractor!

Time Keeps on Slippin' Into the Future

2010-10-16T21:49:00.000-07:00

At our weekly meeting with Paul and Christine this week, we were looking forward to reviewing solar, HRV installation, and insulation bids, and seeing a schedule that would hopefully get us into the house by Christmas. Paul had a schedule, it would not have had us in the house by Christmas in any case, but it really doesn't matter now because the meeting uncovered some problems with the planning that need to be corrected. And that means...yet more delay.

Christine presented the bids from the three solar companies that she has spent the last month collecting for us. If you recall from this post, one of the companies was a roofer who was "looking to get into the solar business". It turns out another was a nonprofit. According to their Web site, they send volunteers up on the roof to install your solar. The bid from this company was the cheapest, and was recommended by Christine and Forrest, our architect. Considering we have about a 45 degree roof, and a previous professional roofer fell from the roof and broke his collarbone, there is no way I am going to let random people clamber around on my roof. I wasn't all that interested in the roofer either. Somebody else can pay for his training. I'm interested in trained professionals who do the job right, and don't punch holes in my roof, and I am willing to pay for that.

In email to Forrest and the previous project manager in July, I asked for SunPower 315 watt panels, the they spec-ed out 225 watt panels. I asked for a maximum power point (MPP) tracking inverter, they spec-ed out a traditional centralized inverter. Only one of the bids came close to matching my specs, and that was the professional solar installation company. I had thought Forrest and Christine were communicating about what I wanted, but, apparently not. I sent Christine and Paul an email detailing *exactly* what I wanted, duplicating my mail of July, and even giving them the telephone numbers of installers and manufactures of MPP systems to call. Christine said she would start the bid process over.

Why am I being so picky about the solar? The main reason is because I want to be able to match the anticipated demand without having to plaster my entire roof with solar panels. With the Sunpower 315's and the MPP system, I can get by with around 20 panels, 2 more than I currently have. With 225 watt panels and a centralized inverter system, I would need 32. That would mean that I would need to put the panels on the east side of the roof, which would not get any sun in the afternoon. Since the highest PG&E solar tariff is in during summer afternoons, keeping the panels on the west side of the roof - where my panels are now - means they will earn the highest return, in addition to offseting the electricity use.

The difference between the power output from the two types of panels partially explains how I can approximately double the amount of energy I get now out of only 2 more panels than I have now (we now have 18 panels, 165 watts per panel). The other factor is the MPP tracking system. There are now two kinds of power maximizing technology for solar that has come available in the last couple years: microinverters and MPP tracking. Microinverters convert DC to AC directly at the panel rather than at a centralized inverter. The advantages of microinverters are that you don't need any high voltage DC wiring, which is tricky to install, and you don't need to string the panels like series Christmas tree lights. With series Christmas tree lights, if one goes out, the whole string goes out. Similarly, with solar panel strings and traditional centralized inverters, if one panel gets shade or clouded, the entire string stops contributing power. With microinverters, the wiring on the roof is AC and the panels just contribute whatever they can without any hindrance from the others.

There are however two problems with microinverters. One is that the most popular, Enphase, uses electrolytic capacitors, just like centralized inverters, that dry out. So they have a lifetime of around 15 years instead of the 25 years that panels have. There are microinverters around now that use film capacitors and have 25 year guarantees, but they are very new and may be hard to get. A more serious problem is that the available microinverters won't handle 315 watt panels. The maximum is 275 watts. Because the microinverters are installed directly on the panel, they must match the power the panel puts out.

MPP trackers, on the other hand, work differently. The inverter is still centralized, but a small module on the panels performs DC to DC conversion to present an optimal electrical load to the solar panel, and a suitable voltage from the panel to match the load. The result is that the power output from the panel is maximized. MPP trackers require high voltage DC wiring and a centralized inverter that communicates with the MPP modules on the panels. But they are not limited by panel power output. There are two companies making MPP tracking inverters that would handle the 6+ kilowatt array I need, Tigo Energy and Solar Edge. Tigo's will handle the full 6.3 kilowatts, Solar Edge's will only handle 6.2 kilowatts, but I think I could probably get by with that.

In addition to the solar, we discovered that for the upgrade to 200 amp electrical service, we will need to dig up the electrical conduit that connects our house to mains power and replace it. I had asked Forrest twice about this in spring when we were in the planning stage, and the previous project manager (he whose name shall not be mentioned) at least once. Both times I was assured that the conduit was large enough for a 200 amp cable. Paul checked last week, it isn't. So now we have to schedule PG&E to come in and replace it. Being a large bureaucracy, PG&E is likely to take its time, meaning more delay.

Finally, the HRV system design needs a bit of work. If you recall, Forrest had been pushing to extend the mechanical closet on the second floor into the space over the upstairs bathroom door. I was resisting, hoping we could put it in the downstairs mechanical closet along with the electric on demand hot water heater. It turns out that the hot water heater must go above the solar tank, so it must go in the space above the upstairs bathroom door, but there is no need to make that space an extension of the mechanical closet. Unlike gas hot water heaters, the electrical kind can go anywhere, just like a dryer, because they don't need venting or combustion air. So I asked Paul to convert that space into another closet as part of the living space so we can use it for storage.

The HRV ended up in the chase next to the east upstairs bedroom because it was impossible to run the ducting from the space over the upstairs bathroom door or the downstairs mechanical closet to the places we needed it. Our house has two of these dead spaces, one over the kitchen and one over the master bedroom and next to the east upstairs bedroom. With the HRV there, the venting can run below the roof to the living room, east upstairs bedroom, and downstairs master bath, and through a new ducting soffet to the hallway, thereby covering the entire east side of the house (the west side is served from another HRV in the attic). The problem is there are two existing pieces of ducting in that space: an inactive duct for the former forced air heating system and an active duct that vents the downstairs master bath, which runs through the entire chase, from the master bath to the outside south wall.

The inactive forced air duct is easy enough to remove, but the active vent for the bathroom is another story. I have been asking Forrest and Paul about this and also Mr. Former Project Manager before he disappeared. Forrest and Paul had some vague plan about rerouting the venting, but last week I found a great Web site about a house in Marin that was remodelled into a passive house (uses no active heating). On that site, they mentioned that they doubled up the HRV and bathroom ventilation. I asked Paul about this, and he said he would check into it, but we don't know if it is possible to boost the Fantek HRV systems up enough to perform bathroom ventilation.

So it is back to the drawing board for Paul to do another schedule, and it looks like we will not be back into the house until late January, if then. The solar will probably be the long pole in the schedule.

Built Environment Panel at Fountain Blue

2010-10-06T20:52:00.000-07:00

On Monday night, I attended a Fountain Blue CleanTech event. Fountain Blue is a networking forum run by my neighbor, Linda, for Silicon Valley entrepreneurs, funders (VCs and angels), and wanna-bes like myself. People with an idea get together with people who have money and, sometimes, interesting things happen. I hadn't been to an event for about a year mainly because I have been busy with my new job. This event was about the Built Environment and featured a panel including a collection of entrepreneurs, a builder, a VC, and a guy from HP who was obviously their home networking "visionary". Since we are right in the middle of a system remodel to improve the energy efficiency of our house, I thought I would check out what the latest technology is.

Much of the discussion was overhung by the projection that the housing market won't recover in the US until 2014. The panel talked about this projection at the beginning, not uniformly gloomy but making the realistic assumption that any CleanTech built environment improvement must show some kind of ROI (more on this later). They then went on to discuss their particular startup or involvement in CleanTech for the built environment. One guy was looking for early stage funding for a company that was in the process of designing roofing shingles made from PET plastic, the plastic disposable water bottles are made of. He accurately described asphalt roofing shingles, which dominate the market in the US, as a problem because they are made from oil and when the oil runs out, no more shingles. But he forgot to note that PET is made from plastic too. When the recycled PET bottles run out, his company is going to have to buy virgin PET on the market and it is as vulnerable as asphalt shingles to oil depletion.

The topic of home energy monitoring came up, and the usual assertions that "consumers just need more data about how they are using energy to make smart decisions about saving". I turned to my friend Paul and whispered: "People don't care about that. All they want is to be comfortable". A couple minutes later, the VC, Kevin Kopczynski, from RockPort Capital, spoke up and said that they had been approached many times with proposals for companies working on home energy monitoring software and had declined to fund them for exactly this reason. Recently, they funded a company that uses weather report data and data about the house to adjust thermostats automatically so that the temperature stays comfortable. Proprietary algorithms are used to do this. I know we could use this in our home. Our hydronic radiant system has a lot of latency, it takes 2-4 hours to heat the house up to 68 F from 58 F or so where it drops to at night. So we need to have the heat come on at 2 AM if we want it comfortable for the two hours before we go to work (and when the temperature goes down into the 30's, the temperature doesn't make it to 68). But if the nighttime temperature goes up, then the house heats up faster, and it is heated while we are still in bed, wasting energy.

Matt Golden, of Recurve (formerly Sustainable Spaces) was also there. I tried Sustainable Spaces home performance monitoring 3 years ago, and paid $600 for essentially nothing. They did a blower door test and some superficial inspection of my house, got the insulation wrong, then redid the report when I told them about the problem. The report essentially said: "there isn't much you can do for this house, it is pretty well insulated". A year later, I had a thermal imaging test done for $200 by a small company that no longer exists, and it was much more valuable. I could see where the insulation was sagging or had been improperly installed (or didn't exist), and with a blower door test and thermal imaging, it was very clear where there were holes through which air was entering. These guys didn't recommend I do anything either, saying my house was reasonably well insulated, but then they see much worse, and also I guess they knew that fixing the problems and really making our house thermally tight would be difficult.

Matt is really into "low hanging fruit" and he has published on GreenTechMedia.com about how much energy could be saved by insulating houses that are uninsulated. Problem is, most of the houses in this country were built from the 60s through the last few years, and they are insulated, though not well sealed at all, especially the houses like ours that were built in the 60s and 70s. A house that is already insulated can't be insulated better without tearing off the walls, either from the outside or inside, or bulking out the walls by installing essentially a second wall and ceiling. So most of the houses in the US aren't "low hanging fruit", they are hanging pretty high (to the tune of $100K+ in California). Recurve is now into using the home performance data it mines from its customers to come up with data driven home models that it can sell to contractors wanting to do home performance improvement. This is, I suppose, a worthwhile goal, but my experience is most contractors have absolutely no clue about how to properly seal a house, or do any other green performance improvement. Until that problem is solved, most green remodeling will be improperly done and so a waste of money. This is the primary reason why we decided to work with an architect having green building experience in our system remodel.

Greg Howes, of IDEAbuilder, spoke about his company, which designs and builds "prefab" houses. The designs are cut out of wood or steel by automated CAM machines in a factory and fit together at the home site. He mentioned a building in Oregon that went from design to finished product in 2 weeks! Considering we've been sitting here in a torn apart house for 3 months with little progress to show, I was completely shocked. Greg mentioned something about "Passivhaus", a German technology for building a house that uses no energy for heating or cooling, except for the energy generated by the appliances. Active ventilation, like the HRV system we are having installed, is required to keep the air fresh. I spoke with Greg about this afterward, in particular, that the Passivhaus technology was developed for cold, humid climates (Germany, Austria, Switzerland) while in our Mediterranean climate, we have hot dry summers and cool humid winters. This requires a completely different technology. The traditional building materials and architectures for such climates involve walls with lots of thermal mass (adobe) and various tricks of architecture to keep the sun out in winter and let it in in summer. Wood isn't a particularly good material for such a climate.

The other panelists - the builder, a guy from Serious Materials, and the guy from HP - didn't have much interesting to say.

During the summary at the end of the panel session, Kevin Kopczynski had the best summary. He said that people were looking for technologies that didn't require them to make any changes in their lifestyle and required the minimum amount of effort on their part to use. Additionally, the technologies and products had to essentially show payback in 2-3 years that people usually occupy their houses. Products and technologies directed at the commercial market could have a somewhat longer payback time, maybe 7-8 years. Everybody agreed on the panel that if the home upgrades were perceived as essentially free, they would be easy to sell. "Free" in this case means the homeowner doesn't need to invest anything up front, and that the cost of the upgrade went along with the house when the owner moved. The PACE program was the best hope for that, but unfortunately the Feds decided that having the cost of the upgrade be senior debt wasn't acceptable (because it would get paid off first in a repossession). Since the Feds are doing essentially 100% of the home loan financing after the private securitization market collapsed in 2008, their opinion rules.

The event left me vaguely depressed and confirmed the other reason why I stopped going to these CleanTech events. If people aren't expected to change their lifestyle, and want clean tech for free, what hope is there that the problem of global warming is going to be solved by business? People are willing to pay lots of bucks for cell phones, tablet computers, plasma displays, songs on iTunes, and other entertainment and communication technology and content, but they refuse to shell out any money for products and technologies that will reduce carbon emissions. Nobody is committed enough to go through the grief and financial load that we've been going through with our system remodel. The Congress and President have failed in political leadership, in enacting policy that will make carbon-based energy expensive or otherwise encourage people to make decisions that involve less carbon intensive purchases and activities. The Feds even managed to sideline a program like PACE, which wouldn't cost any level of government anything.

The constraints on solving the problem are just too tight.

Some Progress, Mostly Not Noticable

2010-09-30T20:25:00.000-07:00

The reason I've not been posting is that not much is happening on our job. The project manager who didn't do anything for 2 1/2 months disappeared, taking "leave of absence" for stress. The guy who took over project management, Paul one of the co-founders of the combined green architectural/construction firm we are using, now has 5 jobs in total, including three that the former project manager dumped on him, and he's pretty swamped. Today during a meeting I asked him when the 200 amp electrical service was going and he said: "What 200 amp service?" Bad sign. It seems other customers were complaining too, and the whole situation was almost a duplicate of the case last summer with the solar thermal installation and the incompetent plumber.

Anyway, I've been encouraged by the reports I'm getting, though of course it will be even nicer to see some work actually being completed. Paul and his assistant Christine put out the solar for bid, three bids came back. One is a roofer who "is interested in getting into the solar business". Hmm. Am I "interested in acting as a training site for a reduced fee"? This is a question I need to ponder. The solar company who put our system up in 2004 punctured the roof in at least 3 places, two of which we only discovered recently after the roofer on the current job did a leak test. The third place was an ongoing battle getting the previous roofer to fix, he finally fixed it this spring but in the quickest and least likely to last way possible: he sprayed polyurthane foam over the roof in the area of the leak. We had extensive mold damage in one closet and had to tear out the drywall, treat the mold with chlorine bleach, and redo the insulation on the ceiling, put back the drywall and paint. At least this current solar installer is also a roofer, so he will probably do a good job on the roof. But whether he'll do a good job on the solar design is another question.

We also finalized the location of the HRV vents. This was a long and complicated process, since I was interested in getting exhaust vents high in the central hallway, which has 20 foot ceilings. The idea is to draw down the stale heated air that rises to the cathedral ceiling, extract the heat, and recirculate fresh heated air in the lower part of the house. We ended up adding two ventilation chases, one in the back bedroom and one in the front bedroom closet, that will exhaust air from near the cathedral ceiling in the hall. We also had to move the HRV on the east side of the house into the chase under the roof above the master bedroom. If you recall, our HRV system consists of two independent HRV units, one on the east side of the house and one on the west. The west side is simple: just install in the attic. But we never really figured out what to do with the east side. Forrest, our architect, thinks we can keep the noise down by hanging the HRV from wires so that the vibrations are not transferred to the building structure, keeping the master bedroom vibration free. We will see.

Forrest finally convinced me that the electric on-demand backup should be installed in a newly constructed overhead closet above the upstairs bathroom door. He told me a while back that NREL recommends backup hot water heaters for solar to be installed above the actual solar storage tank, but he never told me why. While traveling in Europe, it suddenly occurred to me one day that this was probably because the hot water from the solar tank would rise into the connection pipe with the backup water heater, eliminating the short gout of cold water that would hit the on-demand heater if it were below the solar tank. This would thereby ensure that the on-demand heater doesn't switch on and then quickly off when the hot water is drawn out of that solar tank. I was holding out for putting it in the mechanical closet where the current gas-fired tank backup heater is.

Paul keeps discovering stuff that the now-departed project manager forgot to do. Apparently, he never wrote anything down. The electrical service upgrade is just the tip of the iceberg. But slowly, Paul and Christine seem to be getting the job in hand. Although it has been really hot this week - actually, the first long stretch of hot weather we have had all this summer - colder and rainier times are coming. If the work is not complete by Halloween, so that we can move back in, we are going to have to work out some way of keeping part of the patio outside our bedroom door dry so we can continue to live partially outside. Right now, we are living in our master bedroom suite, with a long walk around the building to get into the kitchen through the garage.

Lack of Progress

2010-09-19T13:01:00.000-07:00

While on my recent business trip in northern Europe, daily emails flying between the lovely wife and the contractors left me somewhat disconcerted. The upshot of the emails was that nothing was getting done on the job. It seems the project manager consistently didn't show up to open the house for subcontractors, or didn't even schedule the subcontractors, and basically seemed unable to plan and execute on the job in a professional manner. This was not something we had anticipated, since the architecture and contracting firm that we had selected, founded by the two guys dedicated to and knowledgeable about green building, came highly recommended.

As it turns out, we and they were victim to exactly the same problem that we had last year with the solar thermal contractor. The project manager had only been working for them for 8 months or so, so they really had little idea about how reliable he was. Hiring someone is always a gamble. The resume looks good, the person looks like he/she will work well with people and is personable (as this guy was), but when it comes time to execute and deliver, they fall short. Perhaps this guy wasn't able to handle more than one project at a time, it sounds like they were asking him to do 3.

Anyway, we've told the architect and the head of the contracting part of the business that we no longer want to work with the guy they put on our project as project manager because he was not getting any work done. In the 2 1/2 months the job has been ongoing, the only thing he managed to get done is have the drywall removed (and even then he missed one wall and the ceiling of a closet), and put in some steel reinforcing where structural problems were showing up. The homeowner inspection prior to foam insulation was supposed to be on Sept. 20 and we are nowhere near having enough done for that. Before we had him taken off the project, the project manager said something about the structural engineer wanting additional re-enforcing around the skylights, which might involve having to open up the roof, so we may be more than a month away from the homeowner inspection.

There has been some progress. Here's a few pictures showing the steel reinforcing the framers put in. This one shows how they joined the two halves of the header that the former owner drilled through for the hall toilet vent:

Here they put a steel plate in to couple the load bearing beam above the header over the sunroom entrance to the header. This is something the former owner forgot to do when he built the sunroom:

And here the two sides of the ceiling peak have been tied together. This is where we were seeing the ceiling cracking. The steel should ensure that the beams don't move:

In addition to structural reinforcing, the framers put up plywood along the two chases where a backing for foam is needed. The fiberglass batt was just tacked on against the drywall, but foam needs a backing to expand against. And they also cut a hatch which will open into the chase so that the HRV system can be accessed for cleaning:

Finally, this past week, the electrician did some work installing new outlets in the garage, some wiring in the living room for an FM radio antenna, and wiring for the electric skylight shades. You can see the latter in the following picture (yellow wire, lower right):

Hopefully this week we'll finally get the information on what the structural engineer wants to do to reinforce the ceiling. It will likely not be cheap, but since we canned the geothermal, we are running a under the original budget, including the design costs. If we hadn't canned the geothermal, we would have been about 50% over by the end. But we are now looking like maybe a month or a month and a half before the job is finished, where we had been told it would be done by the end of September.

Electric or Gas On Demand Hot Water?

2010-08-22T12:23:00.000-07:00

Inspired by Brendon's comments at this blog entry, I took a deeper look at our decision to go with electric on demand backup hot water heating. Brendon maintained that electric hot water heating is much more inefficient than gas because most electricity (around 45% this year) in California is generated from gas, and electricity generation is only about 33% efficient, as opposed to heating the water with gas directly, which uses most of the heat for actually heating the water. My response to Brendon was that since we were offsetting all of our electric use with PV anyway, hot water was another electric use that we could offset, just like the lights we use at night when we don't generate any solar power. We are not storing the solar electrons in batteries, then using them later, as would be the case with a non-grid tie system. And also the electric grid is projected to get greener over time but the gas grid won't.

After thinking about it, though, I decided that we could equally well offset the carbon from gas by generating solar electricity. It would not directly offset the cost, of course, but starting next year, PG&E is going to reimburse people on their net metering schedule for unused solar electricity credit. Currently, any net metering credit simply expires at the end of the year. So we could conceivably be reimbursed for the gas cost indirectly by the amount we receive for any solar electricity that we don't use. The reimbursement rate PG&E is proposing isn't equivalent to the amount you would receive through net metering, but it is certainly better than just losing the accumulated credit. And I wanted to check my assumptions about the greening of the electric grid, to see which type of backup water heater would actually have a lower carbon footprint over the long term.

So I did some calculations. Our current gas fired tank water heater is a 40 gallon Bradford-White, circa 2001 vintage. The Bradford-White web page on energy efficiency has an efficiency of around 0.6 for their "natural" gas fired tank water heaters. I don't know our exact model (it is currently packed behind several layers of insulation and plastic curtains for the remodel) so I took that number as sufficient. We used an average of 6.1 therms per month for hot water over the past few years, of which only 3.66 therms actually ended up heating the water due to the low efficiency. The rest either went up the flue or was radiated out by the tank while the water was in storage. Since we will be using backup hot water for 7 months of the year, this amounts to 25.6 therms or 750.67 kwh per year for backup hot water heating.

The on demand electric hot water heater we are thinking of installing is the Steibel-Eltron DCH-E. Electric hot water heaters have an efficiency of 1, so all of the energy goes to hot water heating. I could not find any data on backup energy use by the Steibel-Eltron, so I assumed therefore that it is negligible. Electric hot water heating would require 750.67 kwh. The carbon footprint for that amount in 2010 in California is 222.26 kg/yr.

Our architect recommended a Takagi gas hot water heater, the T-H2 is their greenest model. It has an efficiency of 0.93, which would result in 27.55 therms per year for water heating over the 7 month season during which we need backup. But it also requires electricity for standby and for ignition. The standby energy use is 196 Wh/day. Assuming that the heater comes on 4x per day for about a minute, it would use 10.1 Wh/day for ignition. So the total daily electricity use during the season when we need backup is 206.93 Wh/day, or 44.90 kwh for the 7 month season when backup is needed. The carbon footprint of the T-H2 for both gas and electricity in 2010 is 159.66 kg.

Now, I've assumed in the above calculations that during the 7 months the backup heater is in use, all of the hot water will be provided by the backup water heater. This is obviously not the case, since the solar thermal hot water heater will provide some heat, though in December, January, and February, it will be minimal. In addition, even in the depths of winter the solar thermal will raise the temperature of the incoming water from 60 degrees as it comes out of the main to around 80-100 degrees, thereby reducing the amount of heat input from the backup water heater. The calculations above scale by the amount of energy needed from the backup heater. If the backup heater only comes on 10% of the time, then, with the exception of the standby electricity use for the T-H2, the carbon footprint for both types will be reduced by 90%. So the calculations should still be good for comparison purposes.

Today, in 2010, the gas on-demand heater clearly has the lower carbon footprint, but not by much. The difference is only 62.6 kg, and that will scale down by how much heat the solar thermal provides. The carbon footprint of the gas water heater is therefore about 28% smaller than the electric. However, the situation is likely to be different as the electric grid (hopefully) gets greener. The plan in California is for the grid to have 33% renewable content by 2020. Today, the renewable content is around 15%. Gas-fired power generation is practically the only fossil carbon generating source of electricity in California of any consequence today. Coal has been completely phased out by PG&E, and oil has not been of any consequence since the energy crisis in the 1970's. Assuming that the planned increase in renewable content goes to offsetting gas-fired power generation and not to reducing the contribution from other non-carbon based sources such as large hydro or nuclear, the result would be a reduction in carbon generated by the grid from 0.302 kg/kwh in 2010 to 0.137 kg/kwh in 2020. Our carbon footprint for hot water if we chose an electric heater would then be reduced to 103.17 kg. in 2020, making the electric backup's carbon footprint 32% smaller than the gas. Note that this calculation accounts for the reduction in carbon footprint in the Takagi electricity use.

The crossover point - where the gas and electric hot water heater generate the same amount of carbon - is in 2013, when the grid should have 22% renewable content, if of course the renewable content is introduced in an incremental, linear fashion between 2010 and 2020. This is surprisingly soon. The crossover carbon footprint is 155.94 kg. The graph below summarizes the calculations. The vertical axis is kg/yr carbon for backup water heating, assuming 100% of the water heating in the 7 month season is supplied by the backup, the horizontal axis is the year:

That said, the assumption of a nice, linear increase in renewable content may be too optimistic. PG&E's record in introducing renewables has not been linear, and the political climate at the moment isn't very good for continued policy pressure on them to do so. Valero, the big oil company, is sponsoring a proposition on the November ballot to suspend AB32 until the unemployment rate goes down to 5.5%, and Meg Whitman, the Republican candidate for governor, has said she will deemphasize renewable energy should she win the election. But PG&E seems to be forging ahead signing power purchase agreements with different renewable providers. The graph below shows the historical and projected (until 2011, when PG&E's current policy on renewable purchases should complete) trend for percent renewable content in the northern California grid (data from PG&E's web site):

Gas on-demand hot water heaters have some other undesirable characteristics:

Ignition is quite noisy and combustion is also not entirely quiet. The Takagi installation manual recommends not installing it next to a room used for sleeping or meditation. In contrast, the electric on demand heater makes a clicking noise when the relay goes on to start it, but is otherwise quite quiet. The most convenient place to install the backup heater is where our current gas-fired tank heater is located, which is across the hall from our bedroom. If we were to get a gas on demand heater, we would probably have to pay to have another space modified for it.
Complex flue and venting is required to support combustion. The T-H2, for example, uses PVC venting because the condensing unit required for high efficiency generates combustion byproduct air that is considerably cooler than is the case for less efficient gas appliances such as our hydronic boiler, and the byproduct air would condense out on the sides of the metal flue that vents our hydronic boiler if it were vented through that, causing it to rust. In addition, air must be vented into the area where the water heater is located for combustion, and it must come from an unihabited space or outside. An electric heater requires no such complex venting.
Gas on demand heaters require 3/4" to 1" gas piping due to the huge draw. Our house has 1/2" from where the main enters the house to the combustion closet. This would require another $4-5K to replace the gas piping. The electric heater requires a 220 line, which will likely cost a fraction of what the gas piping would cost to install.

Based on considerations of cost and convenience of installation, the electric heater wins hands down.

Considering that we will only be using the backup heater for a small fraction of our water heating in winter, except for December, January, and February, and that the greening of the grid (if it happens on schedule) should result in a break-even carbon footprint sometime roughly around 2013, we've decided to go with electric.

What's Behind the Walls?

2010-08-11T19:54:00.000-07:00

Ever wonder what was behind your walls? If you've ever had any remodeling work done, you know that sometimes you can be in for a surprise. Our walls have been off for a couple weeks now, and I did a photo expedition into the curtained off part of the house. There were some interesting findings.

The first one was this:

and it certainly came as a surprise. What you see is one of the biggest No-Nos in remodeling: a large hole cut through a load bearing header. The previous owner installed a hall half-bath, and he cut the hole to run the toilet vent through. In California, with our out-sized earthquake activity, this can lead to a major structural failure during a severe earthquake.

The result is some extra expense and time needed to fix the problem. It should be fixable by running a metal strap across the header and another strap at an angle from the header to the top of the wall. But I've not had a full structural report yet, so I don't know precisely what the structural engineer will recommend.

Here's another one, that I sort of knew would be there:

The blackish stain you see around the ridge is mold. The house originally had a shake roof, but we had it replaced with a composite roof when we moved in . According to buildingsciences.com, a composite roof with fiberglass batt insulation requires a ventilation space under the roof decking so condensation doesn't form in the winter. Our contractor told us nothing about this, and I didn't really know enough about construction at that time to ask (I know more now, and I don't trust contractors to know anymore either). So there are areas on the roof, like this one, that have some mold on them. Not a lot of mold, but still some. The ridge is particularly bad since it is the highest point in the house, so all the hot air collected there and the water condensed out as the heat radiated out through the ridge (increasing our heating carbon footprint). We of course need to get the mold treated, so more time and expense.

Unlike fiberglass batt, closed cell foam does not let air through so it can be installed directly in contact with the roof decking. Closed cell is not only more energy efficient than fiberglass batt, but it also is much less complicated than having to install vents at intervals along the roof, like some of our neighbors have.

Portugal and China

2010-08-11T19:33:00.000-07:00

The New York Times today had an article about Portugal's conversion to green energy. About 45% of the country's electricity comes from renewable sources, including large hydro. Several years ago, a new government came into power with a large majority and simply decided to convert, since the country was importing the fossil fuel for electricity generation. Contrast that with the totally abysmal performance in this country since the 2008 election, and you can see the advantages of parliamentary government. The new system required a new kind of grid in which dispatchers act kind of like air traffic controllers, directing power from areas where the wind is blowing strongly to areas where the power is needed. The number of grid dispatchers - a well paying job - approximately doubled.

The Chinese, too, seem to be pushing strongly on policy to improve the carbon efficiency of their economy. Will it take the US another 20 years to finally wake up?

Thermal Imaging and Insulation

2010-08-04T20:42:00.000-07:00

Around two years ago, we had a thermal imaging study done of our exterior walls and ceiling of our house. In a thermal imaging study, the walls are photographed using an infrared camera. Areas that are colder show up dark blue to purple, areas that are warmer show up light red to white. The study also involves a blower door test, where the house is otherwise sealed and a blower is installed on one door to exhaust air out of the house. Infrared photos are then made of areas where there might be air leaks, for example around light fixtures, plugs, etc. The study showed that our house had average insulation compared to other houses, with several areas where the insulation had failed or was not properly installed resulting in thermal holes. There were also numerous places where the blower door test showed extensive air leaks. "Average" sounds fine, except the baseline is very low. Most houses built before 1970 in California have little to no insulation. After all, the climate here is mild compared to the Midwest and East Coast. Of course, we get subfreezing temperatures in winter at night and 100 degree temperatures in summer periodically, but back in the 50's and 60's, energy was cheap and people who moved from the East Coast were happy with running the furnace.

I subsequently built a spreadsheet model of our house and calculated that we could get about a 30% improvement by doubling the insulating power (R-value) of the insulation using closed cell foam. That prompted us to move forward with the current plans to seal up the thermal envelope of the house in order to reduce natural gas usage for heating. With the exception of a couple areas, the drywall and insulation are now off the inside of the house. The temperature inside is about twice as warm during the day as beforehand (and maybe twice as low at night). Just as for the solar hot water tank I measured last fall (reported on here), insulation does seem to make a real difference in temperature control. This is good news, since our primary effort on this job is to substantially increase the insulation.

Here's some pictures of the inside of our house without drywall. Here you can see the pellet stove and the fireplace without insulation around it:

The fireplace area was one of the worst areas in the thermal imaging study. There was essentially no insulation around the fireplace. This thermal image shows the area above the fireplace:

The colored bar on the side shows colors corresponding to temperatures. Further toward purple is colder, further toward red is warmer. The horizontal light green to yellow lines are the studs you see in the picture above with the drywall off. They are warmer than the cavities, which are the turquoise areas between the lines. Typically, in a well insulated wall, the cavities are warmer than the studs because the insulation material filling the cavities transfers heat much less efficiently than the studs.

Here is what the west wall of the family room looks like with the drywall off:

This shows the wall between the sunroom (protected from construction dirt by the plastic curtain) and the side door.

In the thermal image below, you can see that the insulation in the stud bay next to the door was either omitted or was so poorly installed that it collapsed:

In the thermal image above, you can see that the insulation along the header at the top and the stud in the middle has sagged away from the stud.

The thermal images point out a major problem with the most common form of insulation used in the US: fiberglass batting. Batting is very difficult to install correctly and even when installed, has a tendency to sag with age. Any areas where the batting detaches from the studs results in thermal holes or air leaks. In California, the likelihood that batting will sag is relatively high because of the high amount of ground movement (i.e. earthquakes). Even small movements can result in tears to the paper surrounding the fiberglass, eventually causing the paper to fail and the insulation to sag. Tightly packing the stud bays with batting, blown fiberglass or, even better, cellulose is a superior way to get the same amount of insulating power (R-3 per inch). Closed cell foam is yet better because it seals air leaks tightly and has twice the insulation power (R-6 per inch) but is more expensive. Open cell foam provides the same tight air seal but has the same insulating power as blown fiberglass or cellulose.

Air leaks cause even more heat loss than simple conductive transfer through the walls. In the picture below, you can see some insulation peeking out from under the drywall that was not removed from the area in front of the upstairs bathroom:

In the thermal image below done with the blower on, you can see the air being pulled in around the light on the ceiling right outside the bathroom where the insulation above is at:

Notice how the pink fiberglass is discolored by black dirt? That is from 30 years of air flow entering and leaving the house in winter when the heat is on (and taking the heat energy with it). The fiberglass acts as a filter, removing all the dirt from the air. While it is nice to have fresh, filtered air inside the house, pulling it randomly through the ceiling and walls doesn't seem the right way to do it.

Our plans for the system remodel are to seal the thermal envelope and instead ventilate the house through the heat recovery ventilation system. This will pull fresh air into the house and exhaust stale air out in a controlled manner, through a heat exchanger which transfers heat from the inside air to the outside, so the heat doesn't get lost. It also filters the air so that the black dirt you see above doesn't end up on random inside parts of the wall, but rather on a removable filter that can be washed periodically.

Nissan Leaf

2010-07-28T20:20:00.000-07:00

I got email from Nissan the other day. The date for ordering our Leaf will be in January, 2011. Can't wait! Our 2002 Prius is a fine car, a bit thin on the acceleration side though better than stock with the Pulstar plugs. But having a car that runs totally on clean, solar electric is something I've been looking forward to. Hopefully, it will not totally demotivate me from riding my bike.

More on Costs

2010-07-25T20:43:00.000-07:00

I've refined the carbon footprint calculations and cost estimates for our previous carbon reduction measures and for the post 2011 projection after the system remodel and electric car. My previous cost calculations have been based on the cost per kg. carbon reduced over the next year. That isn't quite a fair comparison, since if we had continued to use fossil fuel, we would have generated carbon every year and payed the cost of the fossil fuel every year. So in these calculations, I've calculated the cost per kg. carbon reduction over the projected lifetime of the reduction measure. As a rough estimate, I've used 10 years for the electric cars since the battery life is probably that long, though it might be longer or shorter, and 30 years for the measures on the house. For the new refrigerator, I've estimated 15 years and for the solar hot water system, 20 years. Also, I've ascribed the cost of the reduction measure for making an electric car into a zero carbon emitter to the solar PV, since the lifetimes of the solar PV and the car are so different (10 years for the car, 30 years for the solar PV).

First, the refined carbon footprint calculations:

The most effective reduction measure in our current plans is the solar PV. It results in a 17% reduction, causing the total reduction from the estimated 2002 base line to increase from 54% to 71%. The next most effective reduction is the electric car, at 13%, followed by the insulation and on-demand hot water heater, at 6%. It seems that natural gas usage is the most difficult carbon emission to offset.

Here's what the evolution of our carbon footprint looks like:

As discussed in my previous post, the solar PV contributes more zero carbon energy to the grid than the house uses, making the electricity footprint negative and offsetting the natural gas and gasoline footprints from heating/cooking and transportation.

Finally, the per kg. cost of the reduction measures calculated over the projected lifetimes:

The most cost-effective reduction measures here tend to be the hybrid/electric car, followed closely by the solar hot water and the new solar PV. The old solar PV and the pluggable hybrid are next, followed by the measures taken to reduce gas consumption from heating, including the double pane windows and reinsulating the house. Finally, the refrigerator is last.

The refrigerator was the most expensive because we bought a high end fridge in order to avoid having to reconfigure the kitchen for something else. The kitchen has a Subzero sized hole exactly where the fridge would fit, anything else would have involved some cabinetry work to reconfigure the hole. I can't say I am a big fan of high-end fridges, but the kitchen looks pretty nice the way it is, so we just decided to go for it. The cost of the measures taken to reduce the heating are also no surprise. We are basically ripping out the walls and putting in new insulation. It's a big, dirty job and it involves a lot of hand labor, hence the expense. But, as a practical matter, we need to put some steel in the hallway ceiling anyway to prevent the drywall from cracking, so we would have had to pay for the scaffolding, etc. for that anyway.

The cost of the plug-in hybrid is higher than the hybrid and electric cars because we got no subsidy for it. Neither the state of California nor the Federal government was giving out subsidies for plug-in hybrid conversions in 2008 (they since have changed policy and it is now eligible). The subsidies make all the difference, the Nissan Leaf would be around $10K more expensive without the subsidy. Hopefully the need for the subsidy will diminish over time as battery costs decline.

Surprisingly, the solar PV and solar thermal systems are close to the most cost effective. Most commentators rate them as expensive, and rate efficiency measures as more cost effective, but what such commentators are talking about is maybe putting weather stripping around your windows, not removing the walls and putting in more insulation. In reality, you need both. Reducing electricity demand by plugging power vamping appliances into power strips and turning off the appliances on the strip, replacing frequently used lights with CFLs, and buying new, power-efficient Energy Star appliances is necessary to reduce the electricity demand to the point where solar PV can completely offset the demand. Otherwise, the cost of solar PV is too high.

Natural gas use for heating and cooking remains the most difficult carbon generation source to remove. The work we're planning to reduce natural gas use for heating involves quite a disruptive change in our house, essentially replacing the insulation in the thermal envelope, but it will not reduce carbon emissions from that source to zero. We will still need some heat. If we had gone through with our plans to install a geothermal heat pump, the cost would have been even higher, much higher in fact. These considerations point up the carbon cost of our preferred built environment style for family residences in the US: single family housing with all four walls and roof open to the elements. With more multiple family housing, the cost of heating can be reduced substantially, though, of course, at a much higher expense due to the replacement of the existing built environment infrastructure.

The 10% carbon emissions that we can't reduce is about equally split between transportation and heating/cooking: 887 kg for transportation and 1300 kg. for heating/cooking. For now, it seems like we are at the limit of what we can do with current technology and our pocketbook. We need a car to get out of town. We could get a Chevy Volt which has much better gas mileage than the plug-in Prius, but our plug-in Prius works fine so it seems there is no need to buy something new (besides, I have a fondness for Toyota products). And, as mentioned, the cost of removing the heating/cooking carbon emissions from natural gas is simply too high. So, our only choice is to offset our carbon emissions by buying carbon offsets. The graph also shows the cost of buying carbon offsets from CoolIt.org and PG&E's Climate Smart program. In each case, the cost is pennies or fractions of pennies per kg. carbon offset. Carbon offsets are, by far, the most cost effective way to reduce carbon emissions.

Which brings up the interesting question: why not simply buy carbon credits and forget about taking the reduction measures? The reduction measures are from 10x to 100x more expensive. Many commentators are skeptical to negative about carbon offsets, because in the early days of carbon offsetting some projects were scams or would have proceeded anyway even without the offset. But both CoolIt.org and PG&E seem to have credible programs where the projects are solid and specifically designed as offsets, and PG&E's is even tax deductible (tax deduction was not included in the per kg. cost of the figure). If everybody bought offsets and nobody took any real, concrete measures to reduce carbon, we would be left with a built environment and transportation infrastructure that generated exactly as much carbon pollution as today. In reality, as with efficiency and solar PV, you need both concrete reduction measures and offsets. Implement the highest degree of reduction measures you can afford and use carbon offsets to take care of the rest.

Miscellaneous Items

2010-07-24T21:21:00.000-07:00

Looks like the drywall removal is set to start on Monday, a month after the job was supposed to start. But because we removed the geothermal heat pump from the plan, the job should actually complete about two weeks before the original plan. I'm certainly happy that things are finally getting started.

On the other hand, less thrilling is the fact that the US government now has completely and totally abdicated doing anything serious about climate change. The Senate has dropped any attempt at pricing carbon and now is contemplating a few minor changes, primarily around responding to the Gulf oil spill disaster. It's business as usual on the policy front: we are completely on track for the IPCC's Business as Usual scenario in which the world roasts by 2100.

What happened? Obama basically gave up. He could have come out with a strong speech rallying wavering Democrats and even trying to corral a couple of Republicans who have been sympathetic, like Lindsey Graham. But he did nothing. Peculiarly, something similar happened with his ambitious plans to reform NASA. He unveiled plans in February to scale back on Bush's moon program because the plans were so grandiose and the technology being proposed so deficient that the US wouldn't have reached the goal until 2030 if then. The amount of money needed was much larger than the US could afford. His plan was to turn development of Earth to orbit transportation over to the new, entrepreneurial companies that are building rockets more cheaply than the government can. But he failed to push the plans, compromised at the first sign of opposition, and now the House wants to continue the Bush plan but at a lower funding level (practically guaranteeing that nothing will happen) purely as a jobs program.

Is there any commonality in these two occurrences? They both involve policy making about science and technology that require difficult decisions in which some political pain will be involved. In the case of pricing carbon, the price of carbon-based energy will go up. In the case of NASA, government employees will lose their jobs. In both cases, it seems the US government wants an easy political out, like buying an iPod for 400 bucks, rather than the hard and difficult work of making policy that will be expensive but, in the end, will make the country and the world a better place. The problem, particularly with climate change but also with space, is that the physics and economics aren't subject to compromise. For climate, if we continue on the BAU path, the planet will cook, and the only way to get off that path is to make carbon-based energy more expensive. For space, the government's record of technology development over the last 40 years has indicated that it can't develop economical solutions to the problem of getting to orbit. So it's back to where we were 2 years ago with the Bush administration as far as climate change goes.

What might the world look like after 2100 when the oil runs out and the ice caps are melted? An interesting perspective can be found in the science fiction book The Windup Girl (warning: don't follow the link if you don't want the plot revealed) by Paolo Bacigalupi. The book is set in 2100's Bangkok. Energy is supplied by windup springs, biogas, and human and animal labor, plus coal that is carefully rationed to avoid making global warming even worse. Bangkok is kept from flooding by enormous dikes and coal-fired pumps. Since mechanical technology no longer has any energy source to power it, the world has turned to genetic engineering and the results are environmental catastrophes in which most of the world's original biodiversity is gone and has been replaced by genetically hacked organisms. Like all science fiction, this book takes artistic license with the possible reality in order to generate a good, engaging story, but the general setting sounds plausible to me.

I think we can now reasonably concluded that neither the Democratic nor the Republican party are going to do anything about climate change.What will it take to get the government to finally put in place the policy changes needed to stop the world from cooking?

Projected Carbon Footprint

2010-07-17T20:34:00.000-07:00

Since we removed the geothermal heat pump from the system remodel plan, I've recalculated the projected carbon footprint we can expect from our house plus cars next year, after we have the remodeling work completed (hopefully) and have an electric car powered by solar (again hopefully).

The assumptions I'm making are the following:

The reinsulation reduces gas usage by 30% below current average (around 350 therms per year for heating). Several years ago, I constructed a spreadsheet model of the house and calculated what the reduction in energy use would be for changing the insulation to closed cell foam. It came out to about 30%. This ignored the floor, which we will have done, and included the kitchen and master suite, which we won't, though the kitchen ceiling is now at R-30 using fiberglass batt.
The on-demand electric hot water heater provides backup hot water heating in winter so that total hot water gas reduction including solar thermal and backup on-demand electric is 20%. The electric hot water heater will be offset from the solar PV.
The heat recovery ventilation system is around 800 kwh per year (running in winter only) and is offset by solar PV.
We swap out our current, 6 year old polycrystalline 165 watt per panel 18 module solar PV system for a new system consisting of 20 Sunpower 315 watt per panel modules.
The Nissan Leaf which we are hoping to purchase next year uses 0.25 kilowatt-hours/mile and we drive it around 8000 miles per year, which is about what we usually drive our "commuting car" (as opposed to our long distance car which is more like 10,0000 miles per year).

With these assumptions, we can extend the estimated carbon reduction described in this post to the following:

The chart shows an almost 90% reduction in carbon emissions from the estimated pre-2002 baseline. This includes extra capacity in the new solar PV (around 1131 kg/yr) which the house will not use and will therefore offset some of the natural gas emissions from heating.

The contributions from each component (electricity, gas, and cars) to the total household footprint can be seen in this graph:

Notice that the electricity footprint is now negative because the house is generating more carbon-free energy that it consumes. This offsets the natural gas and gasoline usage. One car will be completely carbon free, since it will run off electricity generated by the sun, but our current plug-in Prius will still require gasoline.

Finally, the bottom line: the cost. The following graph shows the cost per kg carbon eliminated:

The cost takes into account the federal and state subsidy for the Nissan Leaf, which brings the price below $20,000.

The efficiency measures here are the most expensive. Reinsulating the house requires taking off the drywall, blowing in closed cell foam insulation and otherwise sealing up any air leaks, putting back the drywall, and installing a ventilation system to ensure that the house gets enough fresh air in the winter when the windows are all closed. This is expensive and disruptive work, but, unfortunately, there is no way around it if we want to reduce the energy use due to heating.

So by the time we finish next year, we should have achieved almost 90% reduction beyond the estimated pre-2002 baseline. Environmental groups are calling for an 80% reduction by 2050, and this is the aspirational target for governments, though, the steps they've been taking are laughable so far. We will have beat the deadline by almost 40 years. The house and cars will not be total net zero energy, but they will be as close as we can get them, given:

We need some way to get out of town with the car, and gasoline or diesel are the only realistic fuel choices right now. We could do an under the table conversion of the plug-in Prius to E85, but unfortunately there is very little E85 available in California.
We have little choice with the heating but to continue using natural gas. The complexity of installing a geothermal heat pump doesn't match the architectural configuration of this house. The house simply does not have enough room for the complex machinery. And the cost of a geothermal heat pump is far and away above the value it provides (something like $700 per kg of carbon eliminated). The amount of money we'll have put into the house for the upgrades even without the geothermal heat pump probably exceeds the resale value, not that we are thinking of selling it of course. Green remodeling does not yet pay in terms of resale value, at least according to a friend who is in real estate. As for cooking, continuing to use a gas stove is a choice: we both prefer gas to electric, and the existing gas stove is still in pretty good condition so we don't see any point in replacing it.

Now, I wish the contractors would finally get started on our system remodel! We are still waiting on a second bid for the drywall removal.