10 Jun HERS Score and ENERGY STAR
As part of our efforts to quantify how energy efficient our homes are, we applied for both ENERGY STAR and LEED certifications. In the first phase that was built, we were pleased to have reached a low score of 53 (lower is better). In order to qualify for the ENERGY STAR rating, a score of 85 or lower had to be obtained. We were extremely proud of this achievement, but not wanting to stand pat, we radically redesigned the building envelope system to ensure an even tighter house on the second phase. This was achieved by using staggered stud construction to minimize thermal bridging, adding a combination of spray foam and mineral wool in the cavity and then topping it off with 1″ of Dow SIS, which has an R-value of 5.5 per inch. The end result is a home that has a stated wall R-value of 33 and an effective R-value of 31. As a comparison, a home built to code only requires an R-value of 19 and is more often than not, effectively lower.
So what does all this mean? Well, we recently received the HERS scores back for the 4 homes which were tested so far in the second phase and the lowest score is, wait for it, wait for it, 48! We are excited to have lowered the score this much, considering that ENERGY STAR increased their standards quite a bit since the first time around.
So, there you have it. All homes tested so far easily reached ENERGY STAR qualification. We are still awaiting our final LEED certifications, and as soon as we receive them, we’ll blog about it.