Friday, May 1, 2009

A tale of two home energy audits

Blower door test apparatus in my front doorway This week I had a home energy audit done on my house -- the second time I had it done this year. Here's why I had it done twice -- and what you need to look for when shopping for a home energy audit.


I had the first audit done in January. I got a reference from a reputable home improvement store for a contractor to do the audit. When they arrived, snow flurries were falling outside; the contractors used the weather as an excuse not to do a blower door test -- which is a key component of a home energy audit.

They did, however, interview me and my wife about our house. They examined the attic, the outside of the house, and each floor inside. They found the source of our cold-first-floor-in-the-winter problem: In the basement, the rim joist at the front of the house -- where the cinder block wall meets the wood framing above -- needs to be air sealed, so air doesn't come pouring in.


These contractors wrote up a nice report -- which included steps I could take to improve my home's energy efficiency, along with how long it would take to recoup the costs. Audit price: $400. However, no receipt or invoice stating what they did.



Fast forward to April, when I meet a home energy auditor at an environmental meeting. He asks me about my experience with the audit, and I say it was less than perfect. We didn't get the blower door test done and the contractor did not provide a receipt. So the guy I just met, a long-time builder from Bethesda named Ralph Smith, offers to do a blower door test for free.


This week he came and did more than that -- he did a full audit of the house, including the blower door test. The latter did yield some new information not revealed during the first audit. Ralph used the blower door test to quantify how bad our problem is, by depressurizing the house and then checking behind each internal door one at a time to see how much air was leaking back in. The results: Our basement registered a 49 on the manometer scale, where outdoor air was 50 (I think it was in some denomination of pascals). So that front basement wall was doing virtually nothing.


Our master bedroom was something like 27, so not very good -- probably because air is coming up the wall. Ralph showed me some likely empty wall spaces that I could have tested and then filled with insulating foam.


Ralph noted that the blower door test -- and the entire audit -- give you an idea of where the worst problems are in terms of air entering or leaving the house. These are not ultra-scientific, exact measures, but they do provide some information.



Ralph will analyze my electric bill from the past year and the audit info, and then send me a report detailing what he found and how I can remedy the problems. The report will also recommend some local contractors. In addition, he'll send my data to the state of Maryland, and they'll also send me a report.


To become certified in Maryland to do home energy audits, Ralph had to pass a week-long class and do a certain number of hours with an audit mentor -- including audits he did with the mentor watching. The Maryland Energy Administration runs the training program as part of the Maryland Home Performance with Energy Star program. Home energy auditors are trained to audit homes and to install whole-house energy improvements. Ralph carried a certification card from the state.

In DC, some folks can get a free audit and some assistance is available for low-income households. Or you can follow the do-it-yourself instructions here. Virginia doesn't seem to have anything online about state-supported or recommended audits, but you can view and download the Virginia Energy Savers Handbook here.


To wrap up, if you want someone to do an energy audit on your home, check for:




  • state certification (in Maryland)


  • affiliation with the federal Energy Star program


  • make sure they'll do a blower door test




Have you had a home energy audit? What was your experience?



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