Friday, May 15, 2009

Energy Audit

Remember all that hand-wringing I was doing in the last post about insulation? That was mostly based on what we'd have to do if we followed LEED for Homes "prescriptive path" for energy efficiency. That path spells out certain requirements you have to meet for your windows, insulation, etc. If you don't meet the criteria for any one of these areas, you can't get LEED.

After further research and discussions with friends, we realized that we could instead follow the more flexible Energy Star Homes path. Under this option, you must become an Energy Star certified home. The way you do this is to achieve or surpass a certain score on the HERS (Home Energy Rating System) Index. An Energy Star Home has a HERS rating that's 15-20% better than a typical home built to the 2004 International Energy Conservation Code. Houses in Northern climates need to get a slightly better HERS rating than those in Southern climates -- I'm guessing because Northern houses require more energy for heating, etc.

For us, being in a Northern climate, it looks like we need to achieve a HERS rating of at least 80 to get Energy Star certified.

The first step in this whole process of getting a score was to have a Home Energy Rater come to the house and test how efficient it is now. With this information, the rater can construct an energy model of the house. We can then instruct him to make changes to the model to determine what our HERS rating will be after rehab. For example, we can see the impact of using certain types of insulation, or of installing a new, more efficient boiler.

We hired George Trappe from Residential Energy Services Co. Ltd. in Westlake. George came recommended by both Kevin and Lillian, our two friends who built new construction LEED homes in Cleveland. He came to the house last weekend and conducted a blower-door test. This was pretty cool. They set up a big fan in our front door and turned it on. The fan exhausts outside, pulling air through the house. Then George and his colleagues ran around the whole house, testing for air leakage on each floor with a battery of tests and instruments that I can't explain. Usually, a HERS rating involves testing the ducts, too -- but we don't have ducts because we have radiator heat.

Once we get our current score and the model is set up, we can start playing around with different solutions to get to the magic HERS number.

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