Frequently Asked Questions
What is the HERS Index, how is it scored and what does it mean?
HERS stands for “Home Energy Rating System.” The HERS Index is a nationally recognized standard for home energy rating. It scores a home in relation to a HERS Reference Home, which scores 100 based on the 2006 International Energy Conservation Code (IECC). In other words, a home otherwise identical to the one being rated but built exactly to the 2006 IECC would have a HERS Index of 100. Each 1-point decrease in the HERS Index corresponds to a 1% reduction in energy consumption compared to the HERS Reference Home. So a home with a HERS Index of 85 is 15% more energy efficient than the HERS Reference Home, and a home with a HERS Index of 50 is 50% more energy efficient. A home with a HERS Index of 0 would be a net-zero energy home, a home that produces as much energy - usually from renewable sources like solar - as it uses.
What is a HERS Rater?
A HERS Rater is a person trained and certified by a RESNET (Residential Energy Services Network) -accredited Home Energy Rating Provider to inspect and evaluate a home’s energy features, prepare a certified home energy rating and make recommendations for improvement. To become a certified HERS rater a person has taken intensive training classes and has passed a certification exam, and has then performed a number of “probationary ratings” under the guidance of the accredited Rating Provider.
What’s the difference between an Energy Rating and an Energy Audit?
An Energy Rating (aka HERS Rating) is a standard measurement of a home's energy efficiency performed by building a computerized model of how a home uses and loses energy. In order to get a house into the computer model an in-depth examination of the homes existing or planned systems is performed, including wall assemblies, mechanicals, insulation levels, wall-to-window ratios, building orientation, etc. The end-result of a Rating is that a HERS Index Score is generated, usually between 0 and 100, which allows a house to be compared to other houses on a uniform scale. The lower the score, the less energy a house will use.
In contrast, and Energy Audit is an assessment of a house’s energy-using and energy-losing systems which is meant to help a homeowner better understand their house’s weak points and better prioritize energy efficiency improvements. Unlike with an Energy Rating, a computer model of the house is not created; rather, the auditor uses his or her expertise in energy efficiency practices and systems to be able to guide the homeowner in making those changes that will make the biggest difference in the house’s energy efficiency. Generally, an audit will result in recommendations about specific areas of improvement, such as “add 5 inches of insulation to the attic to a level of R-44” or “replace the old refrigerator with a new Energy Star model to save $150 per year in electrical costs.”