August 27, 2008 This Old, Old House and Our Energy Audit

 In advance of Maine’s winter winds blowing through our 200-year-old house, and blowing a hole through our budget, my wife and I decided to have an energy audit done on the house. We had already purchased our annual allotment of heating oil, but we bought less than usual, figuring that we would undertake some of the suggested retrofits from the audit.

We hired Curry Caputo of Sustainable Structures in Whitefield, who did a fantastic job.  Curry set up a fan in our front door to create a strong air flow throughout the house, which reveals where hot air leaks out in the winter.  (He had a cool infrared camera to see the hot and cold spots.) He visually inspected the house from attic to basement. He checked the efficiency of our furnace and checked for gas leaks from our stove and propane tank.  We followed him around for most of the morning, peppering him with questions.

(Photo above: An infrared shot of a cold spot in our kitchen floor, under the dishwasher.) 

The upshot? Our biggest issue is the air barrier between our house and the cold Maine winter.  You see, it’s all about the air flow.  The air seal in our basement is bad, due mostly to the condition of the foundation under the ell.  (We already guessed that was the culprit of our high oil bills.) In addition, the metal bulkhead needs to be insulated, and the basement under the main part of the house needs to be air-sealed where the foundation meets the sill. As air leaks into the basement from outside, it creates a chimney effect, which pushes warm air up through the house—and eventually out the attic and roof.  In our house, this effect was worsened by a large hole in the ceiling of a second-floor closet—a perfect avenue for warm air to zoom into the attic. That was something we never suspected was a big deal. But with a little drywall we’ll make a huge difference.

Does it help to have your furnace serviced every year? You bet.  I always wondered about this. Curry found that our furnace was running at 82% efficiency—not as good as the newer models, which can get into the high 90s, but good performance for this one, given its age.

Once the house is tighter, we’ll have to deal with moisture. The basement is wet—like many houses with a granite foundation in our town—but because the house is so well ventilated, mold and mildew don’t build up. That will change, and we’ll have to take some steps to reduce the moisture (sheathing the basement floor and walls in plastic sheeting, and excavating part of the back lawn to divert water away from the basement).

Years ago, we had most of the old windows replaced.  Although the house is much less drafty now, Curry said that he rarely if ever recommends replacing windows, because the return on investment is so low.  That was perhaps the biggest surprise of the day.  Apparently even the best window is still a huge source of heat loss. Better to live in a bunker.  So have an energy audit done before undertaking any major renovations. Otherwise it’s like going in for surgery before you’ve even seen the doctor.

Mathew Scease

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http://blog.nrcm.org/2008/08/this-old-old-ho.html