Tuesday, August 30, 2011

So Long and Thanx for all The Fish!

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:

Tuesday, August 23, 2011

Nissan Leaf

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. 

Monday, August 22, 2011

Retrospective on System Remodel

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.

Wednesday, June 22, 2011

Heat Control

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.

Thursday, June 2, 2011

Plastic Packaging

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.

Thursday, May 26, 2011


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.

Sunday, May 1, 2011

New LED Lights

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?

Monday, April 25, 2011

Solar Fountains

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:

Friday, April 22, 2011

Earth Day Post: Is E85 Worth It?

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.

Wednesday, April 20, 2011

It's Getting Very Near The End...

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.

Sunday, April 10, 2011

How to Get People to Adopt a Low Carbon Lifestyle?

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.

Sunday, April 3, 2011

Roof Comparison

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.

Sunday, March 27, 2011

Job Progress Update

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.

Monday, March 21, 2011

Measuring Insulation Effectiveness

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.