Wednesday, February 23, 2011

Energy Star Certified

We decided to have our new house Energy Star certified. I had two motivations for doing it: I wanted to be able to advertise the house with some sort of green credential if we sell it and I wanted to have an independent third party directing all the various subcontractors toward building an energy efficient house. I feel like it turned out great.

Bill at Infrared USA did our verification and ensured that everybody was building things energy efficiently. Oddly enough, just the fact that we were building a home we intended to have certified seemed to make a big difference in the subs' attitudes. I'd overhear them discussing how to do something and picking a certain option because it was an Energy Star house. I'm not sure if they were required to do it that way to meet the certification, and in some cases I'm guessing it wasn't. However, that sort of green umbrella over the project is the kind of secondary effect I'd hoped to achieve by opting for the certification. Some of the credit for that effect certainly should be extended to our builder, Keith Fraser who made a point to mention the goal.

The news aspect of all of this is that today we had our final blower door test. One of the key aspects of the Energy Star certification is ensuring the house doesn't leak much air. To do that, the tester performs a blower door test with a rig that looks like this:

That rig contains a fan that turns hard enough to generate a specific amount of pressure and an anemometer to measure the amount of air moving through. From that and the volume of the house, the air changes per hour can be calculated. To meet the standard, the home needed to have 4.0 ACH or better. Our house measured over six times better than that, 0.65 ACH. I'm pleased.

The downside of having such a tight home is that we'll need to install an HRV to ensure that the home has sufficient fresh air. In the short term that hurts because it's another couple thousand dollars we'll be putting into the mechanical system of the home, but long term it means that the house will have fresh air that we're not paying to heat which should mean lower heating bills (and hopefully no cooling bills).

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