Last week, while attending a continuing education class, I along with the other attendees saw on a listing the classification for a HERS Index. One student in the class asked, what is a HERS Index? No one was able to answer the question. As is usually, when a question like this arises there will be research done and a blog post to follow that answers the question. This is no exception.
After doing a Google search, the first site that I visited in my quest for information on a HERS Index/Rating was the Energy Star site. What I found was that a HERS rating is a scoring system that involves an analysis of a homes construction plans along with on site inspections and testing. Upon review of the plans the “Energy Rater” uses an energy efficiency software package to analyze the design of the home. The Rater will then make recommendations to the builder that will identify energy efficiency improvements that will ensure that the home will meet Energy Star performance guidelines.
Onsite inspections are made by the “Energy Rater” along with the input from the original plan review are used to generate the HERS Index. The on site inspections typically include a blower door test that tests for leaks in the house and a duct test that test for leaks in the duct work.
So now we know what HERS stands for: Home Energy Rating System.
But What Do The Numbers Mean?
Based on the 2006 International Energy Conservation Code, a home built to these standards will have a Hers Index of 100. The lower the Hers Index the more energy efficient the home is. A 1 point decrease in the HERS Index equals a 1% saving in energy consumption compared to the standard. A home with a HERS Index of 85 would be 15% more efficient than the standard.
Who Does The Testing?
The second site that I went to while searching for information was the Residential Energy Services Network (RESNET) site. From their site we get the RESNET Mission Statement:
• The Residential Energy Services Network’s (RESNET®) mission is to ensure the success of the building energy performance certification industry, set the standards of quality, and increase the opportunity for ownership of high performance buildings.
Certified Rater’s must complete training by a RESNET Accredited Training provider and pass a test to be certified. After certification, the Raters then begin their work of examining plans and helping builders construct more energy efficient homes.