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Solar at Home

Solar at Home


The trials, tribulations and rewards of going solar
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Before we began: A home energy audit, infrared scan and all


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Editor’s Note: Scientific American‘s George Musser will be chronicling his experiences installing solar panels in 60-Second Solar. Read his introduction here and see all posts here.

Last fall, before we decided to go solar, my wife and I had done a fair amount of work on weatherstripping and insulating and had reached a decision point on what to do next. Get a new back door? Replace the decrepit dining-room windows? Fix the bull-headed T in our steam heat piping? (Plumbers’ jargon is even more colorful than astrophysicists’.) In an old house (ours dates to 1868), there are always more projects than time or money, and I hoped an outside expert would help us choose. Besides, I thought an infrared scan of our walls, showing the heat flow in vivid false color, would be cool.

My wife was put off by the $450 price tag charged by local energy auditor, Tom Testa of Home Energy Diagnostics, but knew that she couldn’t stand between me and thermal imaging. (As it turns out, if you want New Jersey state subsidies for installing solar power, you need a home energy audit, so we would have ended up bearing the cost anyway.) I hired Testa in September, and he spent nearly half a day at our place in early November, when the temperature difference between inside and outside was large enough to ensure good infrared readings.

The imager looked like a cross between a digital camera and a cordless drill, and it was definitely fun to play with. If you touch the wall with your palm, the imager will show the thermal handprint. Testa used it to check the quality of wall and ceiling insulation. A house of the age of ours doesn’t have fiberglass insulation or housewrap. Instead, wedged between the interior plaster wall and exterior clapboard is a non-load-bearing wall of bricks. Their insulation value isn’t great, but Testa said it’s good enough that trying to retrofit something better wouldn’t be worth the hefty cost.

For the attic and those walls that lacked brick fill, we’d brought in a contractor several years ago to blow in cellulose insulation, which is basically confetti. Evidently they screwed up. The imager revealed cold spots around the top of the walls where the cellulose had settled. It also found a spot on our kitchen wall that was the outside temperature—the dark spot in the photo above. Later, I took a closer look and found that the exterior siding in this area had bent back and exposed the wood to the elements. We ended up having to shell out $1,000 to replace part of a load-bearing beam.

On the whole, though, Testa said we’d get the most bang for our buck by focusing not on insulation but on air leaks, which carry away a huge amount of heat. To ferret them out, Testa used a lower-tech device: the blower door. He propped open the back door to the house and covered the gap with a canvas door with a circular opening. He inserted a fan and started sucking air out of the house. A controller regulated the fan to bring the house to a negative pressure of 50 pascals, or roughly 0.01 pound per square inch. That, in turn, pulled in air through every crack and crevice, making it easy to pinpoint air leaks.

In fact, the fan turned our house into a scene from Poltergeist. Doors slammed shut. Windows hissed. Gale-force winds poured out of our attic door. To maintain the negative pressure, the fan had to pull 5,800 cubic feet of air a minute through our house, nearly three times as much as in a properly sealed house. Our walls were sieves.

To get a grip on the problem, Testa advised concentrating on choking off the house’s chimney effect. Outside air enters the basement, rises, and vents out the attic. This overall circulation pattern is more important than local problems such as single-glazed windows. Testa said there will be a human colony on Mars before new windows paid themselves off.

So we added weatherstripping and rigid foam insulation to the attic door. In the basement, we got a contractor to close off the leaky bilco cellar door with a proper fiberglass exterior door and seal the rim joist (the part of the basement wall between the ground level and the first floor) with foam boards. Two thousand dollars later, I get the feeling that I’m running my own stimulus package for the local construction industry.

Now, every weekend, I go on hole patrol. I kiss my wife and daughter goodbye and disappear into the basement with cans of spray foam, tubes of caulk, and sheets of foam insulation. I feel for drafts and look for telltale signs of air flow such as cobwebs. I’m just astounded by how many holes our basement had once I began to look for them in a serious way. It’s a miracle of Victorian overengineering that our house hadn’t just collapsed. If President Obama thinks we can rescue our economy by putting people to work sealing up houses, the amount of time I’ve put into our basement suggests he’s right.

Although we haven’t had enough gas meter readings since we started the work to tell whether we’ve recouped our investment, we’ve noticed a definite improvement in comfort. The temperature differential between upstairs and downstairs is much less than it was, and we don’t need to wear sweaters in our kitchen on winter days anymore. I’m not sure the audit told me anything I couldn’t have figured out on my own, but like others, I found it a real eye-opener.

Thermal infrared image of George’s kitchen wall, courtesy of Tom Testa





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  1. 1. PeterTroast 5:18 pm 03/2/2009

    Laughing out loud at the poltergeist comment. During our audit, the breeze was so strong from the kneewall cavities it blew my hair back! And our sieve of a house tested at only 4500 cfm. At http://www.energycircle, we’re big advocates of whole house energy audits. Well worth the investment (provided you’re OK with long list of to-do’s).

    Link to this
  2. 2. astjohn 9:17 am 03/3/2009

    "we dont need to wear sweaters in our kitchen on winter days anymore. "

    do yourself a favour: keep wearing the sweaters, and turn down the thermostat one or two degrees to make up the difference.

    Link to this
  3. 3. davidfuchs42 2:50 pm 03/3/2009

    some one brave enough to go solar in NJ ….. are you doing solar with a syncronizing inverter to pump power back into the grid? I tried a heat pump, pumping the heat through a small thermal power supply (2.5 kw) dumping waste heat to heat my house. It worked nicely, almost got arrested because the unit wasnt UL listed. I love NJ

    Link to this
  4. 4. Old Witch 9:30 am 03/4/2009

    A cheap way to check for leaks is with an incense stick. Light one and see which way the smoke blows. Follow the draft upstream to its source, then plug the hole.

    Link to this
  5. 5. kate.builder 6:33 pm 08/24/2009

    Anyone in the SF Bay Area interested in home energy auditors should check out http://www.ecoproach.com . Their FAQ section has a ton of great information on the audit process.

    Link to this
  6. 6. WillyMars 11:46 am 09/5/2009

    Energy audits are A great way to learn about your home’s inefficiencies. Energy efficiency is the practical and economical way to reduce energy consumption. To learn more about efficiency and lifestyle changes to decrease consumption, visit http://www.austinauditors.com and click the Get Informed tab.

    Link to this
  7. 7. thinkingthermally 9:15 am 05/3/2010

    "A cheap way to check for leaks is with an incense stick. Light one and see which way the smoke blows. Follow the draft upstream to its source, then plug the hole."

    ….and a great way to start a fire. DEFINITELY not recommended. Smoke pencils or dust (talcum powder) is effective and much safer.

    Link to this
  8. 8. thinkingthermally 9:21 am 05/3/2010

    While air sealing is essential, I’m surprised the STEAM heat system was not also targeted. Although replacement may entail more than is obvious from your mention of it, these are typically notorious energy hogs. After reducing the heat load, the next suggestion is to consider the delivery system: as efficient and as small as possible. I’d be interested in your analysis comparing the solar system with continuing to improve the efficiency of your heating (and cooling?) systems.

    Link to this
  9. 9. amanation 1:43 am 11/8/2010

    In this blog we raed the concept of solar Energy.It is the best source of energy to save electricity. It Takes heat directly from the sun is known as thermal energy and in the form of light <a href="http://endthehype.com/endthehype">energy</a&gt; is known as solar energy. Solar thermal technologies uses the solar heat energy to heat substances (such as water or air) for applications for homes and businesses. There are a variety of products on the market that uses solar thermal energy. Often the products used for this application are called solar thermal collectors and can be mounted on the roof of a building.

    Link to this
  10. 10. amanation 1:46 am 11/8/2010

    In this blog we raed the concept of solar Energy.It is the best source of energy to save electricity. It Takes heat directly from the sun is known as thermal energy and in the form of light
    <a href="http://endthehype.com/endthehype">energy</a&gt; is known as solar energy. Solar thermal technologies uses the solar heat energy to heat substances (such as water or air) for applications for homes and businesses. There are a variety of products on the market that uses solar thermal energy. Often the products used for this application are called solar thermal collectors and can be mounted on the roof of a building.
    http://endthehype.com/endthehype

    Link to this

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