Energy Upgrade California—Up Close and Personal Part 3

Here is the latest from the 10 Maple Lane Retrofit Project.

Met with Bill Stewart on Monday and signed an agreement for:

  • Wall insulation
  • Vapor barrier on crawlspace floor
  • Duct repair and some air sealing

I also asked them to move the filter to the return grill so that I don’t have to crawl around in the attic to change the filter every few months. And we may replace our very noisy bathroom fan and this time vent it to the outside instead of into the attic.

All this should earn us a rebate of $2,000, plus $300 back from PG&E for the test in. Our cost should be about $5,500 total before rebates. Some of the measures we are choosing— moving the filter and replacing the bathroom exhaust fan, are good measures but won’t qualify for rebates. We just figured it would be a good time to have these things done.

We decided to leave the HVAC system as is besides having the ducts sealed. We want to reach 10% duct leakage, the minimum to earn the duct sealing rebate, and hopefully even less. I installed a Chimney Balloon and put gaskets behind all the switch plates and outlets in exterior walls. I put some metallic tape around places in the air handler that were obviously leak spots and I think Bill’s crew will do more of that. Our big hope for the future is to replace the furnace and duct system with a mini-split heat pump and as few inside units as possible. A better insulated and sealed house is a plus no matter what we use as a heat source.

But here is some surprising news: I was putting out the trash and noticed some plugs in the wall on the North and Northeast corner of our house (see photo)! I never noticed them before. There are two rows of them, one at about chest level and the other close to the eves, about 16 inches apart! So I think a portion of the exterior walls have already been insulated. I took off a few socket or switch wall plates and looked in carefully behind the junction box to see if there is any insulation visible in those walls. It looks like a previous owner kept the South, Southeast, and West sides uninsulated, I'm guessing to take advantage of solar gain in the winter. We do notice that the North side of the house is a lot cooler than the rest. I wrote to Bill to let him know. It should cut down on the cost.

Anyone hear of insulating only some exterior walls to take advantage of winter sun in Northern CA?

Interesting what gets hidden inside the walls of 63 year old houses. It's also interesting what homewoners notice and when. I must have emptyed the trash hundreds of times but never noticed the "plugs" in the wall until we decided to add insulation to the walls.

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Comment by Jim Nugent on May 28, 2014 at 1:01pm

Hi Jim,

Yes the energypro 5.1 credits you for the wall insulation but in some climate zones it penalizes you because your cooling loads are calculated as if you have an old AC system.

I was told the thought behind it was people would put in an AC system later so the CEC decided to make house show an AC system whether they have it or not. If you have some hot days and no efficient AC shown you are penalized by the additional wall insulation as the heat cannot get out of an insulated wall as quickly. So you are penalized at the higher rate for AC even though you have no AC.

That is why we stopped doing EUC in the costal climate zones. Made no sense not to insulate them and open the windows occasionally.

We also try to only inject from the inside of the house so we do not penetrate the vapor barrier.

Yes and with proper insulation and sealing we can usually save a homeowner 40% on there overall bill. So I am a huge believer in Passive Home technology. As it is the most cost effective, the home is always more comfortable, and it works day and night without any further costs for the balance of the useful life of the house.

Comment by Jim Gunshinan on May 28, 2014 at 11:55am

Hi Jim. Thanks for your comments. The software that the Energy Upgrade program uses does credit wall insulation, but we do have an HVAC system (just the furnace). Not yet ready to go Passive House! They are using EnergyPro 5.1 for modeling purposes. We aren't using foam, unfortunately, but cellulose. Yesterday while the crew working with Stewart Heat and Air was blowing insulation into the walls from outside, we got a cellulose shower in the shower! There is a big gap I have to fill around the shower-head supply pipe/wall interface.

I was surprised that insulating my walls would make a big difference, in our climate. I thought a sealed and insulated attic floor was the best you could do for the money.

Comment by Jim Nugent on May 28, 2014 at 10:20am

Yes we inject walls with a pre expanded foam individually for both energy and sound.

Many times it is a room that is always to hot or cold. It is amazingly effective as it both seals and insulates.

We use a thermal imaging camera to locate the studs and the blocking. Then after injecting we check the walls again with the camera. The foam has a catalyst which heats it is very easy to see if we missed anything  as the foam shows up as bright red where it has been injected.

It would be much better to do the whole building but sometimes do to monetary constrains the client doe not wish to.

We use 2" holes as it is gives the installer a better feel for how the injection is going.

Did you have problems with the modeling in your climate zone if you do not have hvac. In our coastal climate zones we can get heavily penalized for adding insulation to the walls. The modeling software and CEC penalize you for heat loads if you do not have a HVAC system. So the more insulation you put in the walls the lower your energy score goes! Clients looking for rebates only sometimes chose not to insulate the walls?

Comment by Jim Gunshinan on May 23, 2014 at 5:10pm

Thanks George. You give me a lot to ponder, but thanks for affirming what we are doing right! We are in it for the long haul and every time we do an upgrade or replace an appliance it is a chance to explore and learn new things about our house. Sure makes the articles I edit for Home Energy come into three dimensions and in full color.

I am glad to be a part of a community where I can share experiences and ideas with some really smart and experienced people such as yourself.

Comment by George J. Nesbitt on May 22, 2014 at 10:42pm

In the winter uninsulated walls will loose far more heat than they gain, will be cold & uncomfortable, and encourage mold growth. In the summer they will gain far more heat than they loose, and be hot & uncomfortable. The north wall is cooler because it gets less sun as well as it's insulated.

I'm not surprised that wall insulation provides so much calculated savings.

I have always recommended wall insulation. Unfortunately 20 years ago the practice was 3/4" holes, 16 o.c., and to this day I still see 1" holes. The problems? they are too small to probe to check for blocking, and adjacent studs, so cavities get missed. They are also to small to insert a hose into the cavity, so the a nozel is used to install the insulation, and you can't densepack (>=3.5# cu. ft.) and get the air leakage benefit.

When I was in the predecessor to EUC, the RCP (Residential Contractor Program) we were required to use a 1-1/2" hole, within 1' of the top of the wall, and a maximum of 4' apart. 1-1/2 is about the minimum size that you can probe easily, especially with stucco over 7/8" sheathing.

When I started blowing walls myself, I went to a 2-1/2" hole, and a 1-1/2" hose inserted into the cavity to densepack.

I'm not sure if it's better to insulate walls wrong than not at all. The cost to go back, re-drill and densepack would be as much as doing it right in the 1st place.

Air sealing is always a good thing to do, but probably does not show much savings in the calculation.

 I can get most existing duct systems below 6%, lower is better. Unfortunately your previous test results showed they were tighter, but now leakier again.

Crawl space vapor barriers are another always recommend item, it's so much nicer to work in a clean & dry crawl. Of course the benefit is reduced moisture, dust, and gasses (if fully sealed), not energy use.

Your "62%" efficient furnace, would have been below federal minimum for the time. I've tested wall & floor furnaces as well as central furnaces (with & without fans), and almost always 80% of the heat does not go up the flue / vent. Any central gas furnace (with a fan), and natural draft I would consider to be 78 AFUE (pre 1978 75 AFUE would be a valid according to CA Energy Code), with a fan induced flue / vent it would be 80%.

Tweaking values in energy modeling to get results seems to be a common issue from what I see. People want to downgrade insulation based on poor installation, but the energy code software already does this (EnergyPro & Micropas) unless it's Verified by a HERS Rater as QII (Quality Insulation Installation) or Grade 1 (RESNET).

Comment by Graham Irwin on May 22, 2014 at 12:17pm


Unlikely the walls were left uninsulated for passive solar gains (minuscule compared with windows, regardless.) My guess is that the walls that got insulated were having interior mold issues, and the owner only insulated the walls he/she had to for that problem.



Comment by tedkidd on May 22, 2014 at 12:04pm

Cool!  Be interesting to have some basic numbers for orientation.

Blower door #?

Duct leakage? outside? 

Square footage?  

Annual KWH.  Annual therms.

Some of the measures we are choosing— moving the filter and replacing the bathroom exhaust fan, are good measures but won’t qualify for rebates. We just figured it would be a good time to have these things done.

Nicely illustrates one of the many perversities of EUC incentive structure.  That, and the fact they are paying for nearly 50% of the improvement. 

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