Initial Report on Our Household Energy Project

Last March, I reported on the results of an energy audit that we had done on our circa 1850 farmhouse in the hills of upstate New York, together with expected results of the project the contractor proposed to perform to improve our efficiency (1, 2, 3, and 4).  It took a while to get the project organized and approved, but eventually it went ahead in September of last year.

Today I wanted to give an initial report on how things are working out so far.  It would have been ideal to wait until the end of the heating season, but it happens that we were asked to be on the Dryden Resource Awareness Coalition's energy tour tomorrow morning (Saturday), and so I'm doing some calculations now to be able to give information to tour participants.  (Any readers in the area are welcome to drop by - time and place information at the link above).

To recap, when we first moved in, we had a wood stove and pre-existing baseboard electric heat.  The wood stove could not keep the entire house to a reasonable temperature, and the baseboard heat was used extensively.  We had an energy audit performed and it turned up a variety of issues.  Although the walls were insulated tolerably well, and the attic was insulated, a lot else was not great.  In particular, the house was balloon framed and a lot of the interior walls opened into the attic.  The stone basement was vented to the outside, and was extremely damp - water dripping from the floor joists and plumbing year round, frequently standing water on the basement floor.  Overall, the house allowed a very high level of infiltration - 5155 cubic feet per minute at 50 pascals pressure difference.  It's likely that in practice a lot of infiltration took the form of cold air we being pulled into the basement, up through the flooring into the house and then out the attic, due to the stack effect.

Snug Planet proposed to do work in four main areas.  They air sealed all the gaps in the attic and blew in additional cellulose insulation to bring it up to R-49.  They air and moisture sealed the basement using a mixture of heavy plastic fabric and spray foam.  They reinsulated a small side-attic in our house that had a lot of very poorly installed ragged fiberglass.  And they replaced a number of our older appliances with high-efficiency modern ones; most significantly, a new heat-pump hot water heater.  All of this was done via New York State's on-bill recovery financing over 15 years - we put out essentially no cash for all the work.

Here's a few photos to illustrate the work.  Here's the side attic, with the ragged fiberglass replaced with a neat box of foil-faced polyisocyanurate which encloses the plumbing in the wall to the right (there's a bathroom on the other side of this):

Here's the basement, no longer a muddy stone-walled hole in the ground:

The ragged fiberglass between the floor joists was pre-existing.  You can imagine how well that was working.

We added the carpet to protect the plastic membrane and drain matting on the floor.  The vertical strips of carpet lead to crawl spaces off the main basement.  They are there so the cat can easily patrol the whole area for mice without scratching the plastic (you can see the cat bowls in the right foreground).

The project has made the basement usable for certain applications which don't fit well elsewhere in the house:

Previously, it was pretty unusable space because it was so damp and unpleasant.  Here's a detail of spray foam sealing of the stonework:

Flopsy the cat is in there too, if you look carefully in the shadows, as she was very intrigued by my intrusion into her domain.

Here's the heat pump hot-water heater:

So far, this has been performing its appointed function with no fuss or difficulty of any kind.  It is noisier than an immersion-type heater, but we don't notice the noise down in the basement.  It uses less than half as much electricity as the most efficient immersion heaters.

Between all the air sealing and the hot water heater (which extracts water from the air and sends it via a plastic line to the sump pump at the lowest point in the basement), the basement conditions are now much healthier:

I didn't measure the humidity before the project, but with water dripping off all the plumbing, I assume it was pretty much 100% all the time.  I have a dehumidifier down there, but it's turned off at present.  We may need it in the summer.

So how did all this do at actually saving energy?  The most immediately striking effect was on the icicles hanging off the roof in January - we didn't have any, whereas most of our neighbors had a lot, some up to six feet long.  This indicates that we have far less heat leaking into the attic than we used to.

Because wood is much cheaper than electricity, we elected to continue to use the wood stove continually throughout the winter, much as we had the previous winter.  In both cases, we got through about 3 1/2 cords of wood, so there was no saving there.  However, the electricity saving was dramatic:

The darker blue line shows cumulative electricity usage through the winter of 2011-2012.  The red line shows this last winter, to date.  This winter was colder than last winter, so the pale blue line shows my estimate of what the electricity usage would have been last winter if it was as cold as this winter (ie corrected for the greater number of HDD - heating degree days).  You can see that overall we cut our electric usage by about two thirds.

It's worth acknowledging a couple of limitations here.  Firstly, heating almost exclusively with wood means a living room (where the stove is) that generally runs about 75-80^oF during the day.  Then the outlying areas of the house might get up to 65^oF in the afternoon, and fall to 60^oF at night.  So this is not American standard 72^oF everywhere.  We kind of like it this way - a very warm cozy living room, and then cooler in the bedrooms, but not everyone might.  Also, my wife is a full-time homemaker, and I was telecommuting to my job for most of this period.  We are around a lot to keep the stove fed.  A dual career family would probably need a pellet stove to accomplish a similar result.  Also, a couple of rooms at the opposite end of the house from the stove would never stay warm enough and we used the electric baseboard sparingly to keep them usable.

While we are saving a lot of electricity, are we saving money?  Here we have to account for the fact that we have now added a $123/month payment to our electricity bill for the work that was done.  This next graph compares the cumulative cost of utility bills this winter (red, including the loan payment), to last winter (blue, including the correction for temperature):

You can see that we saved almost $1000 through the heating season.  It's not clear yet whether we will save money in the summer when we only have the benefit of the more efficient appliances to offset the loan payment.  However, we have almost certainly saved enough in the winter to offset any possible loss in the summer.

Finally,  I want to report on how reality so far compared to my projections based on a heat flow model of the house.  This last graph shows as the left two columns my estimate of heat inputs and outflows from the house done last spring.  The right columns show my estimates now:

My projection of electricity usage was accurate to within 3% (which must be a fluke to a significant degree).  However, we used an additional cord of wood relative to what I expected.  The main reason is likely that the project did not cut infiltration as much as I had hoped.  I was projecting a final blower door measurement of 2500cfm@50pa, but Snug Planet actually achieved 3300cfm@50pa (vs the original 5155cfm@50pa).

Overall, while the project didn't cut energy usage quite as much as I projected, the project economics are still very clearly positive.  Furthermore, we created a large new storage/utility space in the basement, which was previously unusable, and probably extended the life of the ground floor joists significantly.  We also got a number of new appliances.  All for zero cash outlay.  I'm pretty happy so far.