What is a HERS, or Home Energy Rating System score? Well it is basically a rating of how energy efficient a home is based on a number of things, including a blower door test, the HVAC system, energy usage, and so on. The HERS rating is what is used to qualify a home for the Energy Star Rating. The rating is based off of a standard new home built to code that was rated originally tested and used as the test case with the score of 100. A typical older home has a HERS index of 125-150. Most homes that qualify for Energy Star homes must have a HERS rating of 85. That means that those homes are 15% more energy efficient than the test house. This is really good and a step in the right direction. Most of our homes have been scoring in the 50's, which is where we would expect the to fall. That HERS score would qualifies our homes as 5 star+ in the Energy Star rating system. The "Vineyard Project" came in at 34 (lower the better) making it 66% more efficient than a new home built to code.
Based on their Home Energy Rating System (HERS) scores, the average home certified under LEED for Homes since its launch in February 2008 is predicted to use an estimated 30-60% less energy than a comparable home built to International Energy Conservation Code. Based on the average HERS ratings for each level of LEED certification, these homes could potentially see energy reductions of:
- Certified: Up to 30%.
- Silver: Approximately 30%.
- Gold: Approximately 48%.
- Platinum: 50-60%.
As many know, Adam and I are firm believer in Kaizan ( A Japanese philosophy Adam introduced me too), or continuous improvement. We are continually studying the design & construction of our homes to make improvements to them so they are as energy efficient as possible within their budgets. So even though a HERS rating of 34 is the best we have achieved so far our goal are to continually improve upon that score with the ultimate goal of a HERS score of 0. You can read Adam's take on it at his blog.