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.

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.

Progress on Urbanite and Siding

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

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

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

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.