This credit is the first and major one for the performance pathway, which requires a HERS rating from our green building rater. There is one prerequisite: EA 1.1 : Energy Star for Homes. I am not sure if we have an Energy Star House, but a home that earns points under EA 1.2: Exceptional Energy Performance automatically demonstrates compliance with the prerequisite EA 1.1.
To get our HERS rating, our green rater had to come inspect our house as it was being built — insulation, windows, the HVAC system, appliances, lights, and how the house was coming together. Then, once we moved in, he conducted a blower door test to test the leakiness of the house (through doors, windows, etc.), as well as a duct-leakiness test. He plugged a bunch of numbers into the Resnet Software, and out popped a number between 0 and 100. A net-zero energy home scores a zero, and the standard “Reference” home scores 100 — so the lower the score, the better.
Currently, our HERS Index Rating is 46, giving us 21.5 LEED points for this performance path (if we were located in a slightly warmer state, we would have received 24 points for the same HERS score, but colder climates have higher requirements).
The week of September 13th, 2010, though, we will be installing a 3.68 kilowatt solar system on our roof. Once the inputs from this new system are plugged into the HERS Index model, we will get a new HERS rating. I will then update the number of LEED points we get. (This is the piece that I believe will push us from silver to gold rating.) I will also go through the other prescriptive measures so I can better understand all the inputs required to get this many points through this mysterious model. For now, though, we are getting a lot closer to LEED Certification.
Energy & Atmosphere Points so far: 21.5
Cumulative points: 52.5
Additional points needed to get to Gold: 35.5
We are currently installing solar panels on our roof, which lowers our HERS Index rating from 46 to 39. (That means our house is 61% more efficient than the typical home.) A HERS Index of 39 gives us 24 LEED points (as opposed to 21.5), so we get an additional 2.5 points for our solar system. I will adjust our “Cumulative points” and “Additional points needed to get to Gold” in future posts.
I spoke with our Green Rater about our HERS Rating again, and it seemed that one of his inputs in lighting was incorrect — he did not incorporate how many LED lights we have. When he updated the model, our HERS Index dropped from 39 to 35! A rating of 35 gives us 25.5 LEED points (so the LED lights gave us 1.5 more points). I’ll update the cumulative points going forward.