Home Energy Assessment: Part Two

In Part One of my home energy assessment write-up, I mentioned that our 91-year-old house is very expensive to heat during cold weather –- it can cost us roughly $350 for gas alone in January and February each year. To locate the source(s) of the inefficiency, we had an energy audit in November, performed by home performance consultant Keith Williams.

Keith arrived at 9 a.m. on November 19. The inspection lasted about an hour and fifteen minutes. When he was done with his inspection, I asked Keith several questions about my house, as well as about home energy efficiency in general.

First, I asked Keith to explain his work as energy auditor. He likened his role to that of a doctor. "We give houses physicals because they're energy sick," he said. After an inspection, he sends the homeowner his "prescription" for how to make a house "energy healthy." He also refers the homeowner to "specialists" (insulation contractors, etc.).

Unlike window, insulation, and HVAC contractors, who may inspect homes and write estimates for ways to make a home more energy efficient, a home energy consultant's inspections and recommendations are unbiased because a consultant does not sell products or services (other than the service of inspecting a home, of course).

Keith's inspection consisted primarily of air pressure and wall insulation tests, including an infrared scan and a blower door test. He told me that our house's air change rate per hour is 7.5. That means our house needs to be re-heated about seven and a half times every hour. The goal should be fewer than three.

The main problem with our home, he said, is a few uninsulated walls, particularly one he identified in our upstairs that opens into the attic. Conditioned air is flowing out of the top of our house, causing our home to be drafty, inefficient, and dry.

Incidentally, Keith said the 92% efficiency furnace we bought two years ago will only works at 92% if the house is properly sealed.

Keith has yet to send us his formal report, but in our informal conversation he said adding insulation to the uninsulated walls will be key to tightening up our home and improving our air change rate per hour.

As soon as I've received Keith's final report, I will begin getting estimates on insulation. Then, once we've made certain changes to our home, Keith will come for a follow-up visit to inspect work and verify safety (there are risks that go along with making a home more air-tight, e.g. carbon monoxide poisoning and mold/humidity problems). Keith's inspection fee of $375 covers both his first inspection and his follow-up visit.

With Keith's report he said he will send me a list of consultants who can make necessary changes to my home. In order to be on Keith's list, consultants must meet certain standards; underperforming or unethical companies don't make the cut. Keith said he receives no money from the contractors he refers.

FYI, if you're wondering about the efficiency of your lighting and appliances, home energy consultants don't typically assess these things. Their focus is on home heating and cooling, the most significant part of a home's energy bill.

Here are some other things I learned from Keith during his visit:

On saving money while making a home more energy efficient: Keith said that it's hard to pin down exactly how much money can be saved from making a home more energy efficient, mostly due to fluctuations in temperature, price of fuel, and resident lifestyle (how warm individual families keep their homes). While some changes may cause a homeowner to save money, those changes can be costly, so the ultimate goal of energy efficiency isn't to save money – it's to reduce energy consumption. Generally, though, consumers who make recommended changes to a home can expect approximately 20 percent savings in fuel/cost.

That said, there are many tax incentives that can bring down the high price of retrofitting a home to make it more energy efficient, and having a formal energy audit can make a consumer eligible for some of these incentives.

On fireplaces as a manner of heating a home: Keith said that anything that uses a chimney to generate heat is not energy efficient, as the chimney will suck warm air from the house. Plus, radiant heat from a fireplace doesn't spread very far. A fireplace consumes 20 percent more energy than it produces. Bottom line: don't use a fireplace to heat a home. Use it for entertainment. And remember to keep the flue shut when the fireplace is not in use.

On replacement windows: replacing windows can make a home more energy efficient, but this improvement should be low on the list. Changing windows from an R-value of 1.5 to an R-value of 4 will cost $30 per square foot, whereas changing walls from R-4 to R-19 costs about $2 per square foot. You'll get much more bang for your buck by adding insulation.


As soon as I hear back from Keith I hope to share his verdict and discuss our future plans. In the meantime, have a merry Christmas and a happy, blessed 2010!