(This is Part 7, the final installment of a series about the solar remodel I did on my house in 2007. Start here.)
The interior of the remodel was not complete, but the envelope was done enough to conduct an energy audit. I called my friend, Alva Morrison, who is a Certified Energy Rater. He’s been working in the state weatherization program for a long time and is very knowledgeable about energy conservation. Becoming an energy rater was a natural next step for him in his career.
We were going to conduct a blower door test. A huge fan was placed in the opening of an exterior door and sealed to be air tight. Then we sealed up the other exterior doors, closed all the windows and left all the interior doors open. We were going to need the air in the house to flow to the fan and outside in order to determine leaks.
Alva measured the house to determine to volume of air it holds. He also asked me a lot of questions about my heating systems, insulation, building materials and the foundation. I also gathered up my utility bills so he could see my average annual energy use. All that data was input into the software on Alva’s laptop.
We put the laptop on a table by the door, and connected the fan to the laptop. You can see all the cords in the photo on the left. We turned on the fan, and it recorded the air flow through the house. At the same time, it analyzed the results based on the other information I had given him.
While it was running, we went around the house looking for air leaks. We were surprised to find them in some places and not in places where I expected them! The older windows had some spaces around them, and we caulked them. There was also a small space in the panel where I gain access to the attic space. We tightened that up, too, then rechecked the figures the software was spitting out. With just sealing up those areas, we had improved the house’s energy efficiency.
We were surprised at the analysis, recommendations and ROI, too. Alva included them in his report:
“Nan’s house is a great example of what can be done to turn a pretty average house, built to code a couple of decades ago, into a modern energy-efficient home. If built as is today, it would exceed qualification for the USEPA Energy Star certification, even though many of the walls still have 2×4 insulation in a 2×6 wall. The main factor driving the house’s lean performance is a thick blanket of attic insulation. But the solar hot water and the balmy sunroom, with a thick adobe wall to catch and hold the heat, provide solid backing. Add to that a refrigerator, which squeezes kilowatts until they scream, and you have a working person’s house to take us all through the next century of global warming both economically and comfortably. All these things were added to the house by Nan at moderate expense.
“Analyzing possible improvements was very interesting. Tearing off sheetrock and re-insulating the walls seemed like it should be a no-brainer. But when we ran it through the computer, it only showed a savings of around $25 a year- not much reward for all that trouble. The moral is, heat goes up, not sideways.
“However, we found another weaker spot in the building’s ‘heating envelope’: the uninsulated foundation. A quick rework of the house through the energy rating software showed that digging a barrier of four inch rigid foam in around the perimeter of the foundation would return $175 a year – and that’s if the cost of wood and gas stays the same (don’t hold your breath for that!). Get out your shovel, Nan!”
Hopefully, I can get that work done this summer. It’s kind of back-breaking for me, but I have some energetic friends that could pull it off.
I had Alva calculate a HERS (Home Energy Rating System) score, because I wanted to be able to show others the entire process. Tangible results say so much more than academics.
The number of a HERS score is based on the International Energy Conservation Code (IECC), which is 100. My score was 88, meaning my house is 12% more efficient than the code. The lower your number, the more efficient your home is. When I make improvements, Alva can plug that information into his software, analyze the results again, and give me new recommendations.
Many municipalities, including Taos, are beginning to require HERS scores and/or LEED certification on new construction. This is the only way were are going to get our building to be more efficient. I have found over they years that voluntary energy conservation doesn’t work. Mandates do.
I have now lived in the house for four winters since the remodel. My energy bills are very low. Here are some thoughts on energy:
> My gas bill for hot water, cooking and heating my daughter’s rooms rarely goes over $30, and in summer, it’s usually $18.
> Instead of burning 5-7 cords of wood, I burn about three. This is always hard to judge, because there’s usually wood leftover from the year before, and I burn a lot of scrap lumber and paper trash when it’s not very cold in spring and fall.
> I did not install solar PV, because my electric bill is about $25 a month. It would not be cost effective to install, since the payback would take so long. If I were gung ho about generating my own power and returning it to the grid, I would definitely have PV on my house. It would be a wonderful experiment!
> When I think of selling and moving closer to town for walkability and a smaller home, I figure my bills will be much more than they are here. Even though I have more space than I need, and I have to drive everywhere (I don’t drive to town every day, though), I am still using less energy than I would in a smaller home closer to conveniences. The gas bill in my hybrid car is certainly less than an increase in rent and utilities, so from a financial point of view, I am probably better off staying put until I sell and move away. There are always trade offs in the energy conservation game.
> I’ve cut my grocery bill by being able to grow food indoors year round. It doesn’t take much to do this. A few pots with greens and other cool weather vegetables offsets my food bill.
> Low-e windows and insulation work wonders to reduce energy consumption! I also bought a front-loading washing machine just before this remodel, and it measurably cut back on my hot water.
> Find a certified local Energy Rater through RESNET – Residential Services Energy Network.
Thanks for reading about my remodel! If you have any questions, please don’t hesitate to email me! nan at desertverde dot com.
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