GreenHouse wide What Is A HERS Score?

With an increasing focus on green home building there is also a greater interest in knowing just how energy efficient an already-built home is. The HERS score is a way of quantifying that information. Realtor® Melisa Camp of Phoenix, Arizona, the ‘Green Queen’ of Arizona real estate, explains what the score is and how it may come to affect home values:

Like it or not HERS scores will be entering our mainstream home sales market and you will start seeing more and more of them, but just what is a HERS score? The Home Energy Rating System or HERS, is a numerical value for the efficiency of a home. It is frequently compared to the MPG or miles per gallon rating you would see when buying a car, except the HERS relates to the efficiency of your home. A HERS score would take into account factors such as the home’s insulation levels, the home’s orientation (with N/S exposure being more efficient), the number and kind of windows, the efficiency of the HVAC unit(s), leaks in the home envelope (your home’s barriers to outside elements), leaks in ducts, and electricity generation like solar panels.

A RESNET certified professional would use performance testing like a blower door test in addition to energy modeling software to give you a numeric score. The lower the score the better. A new home built to standard 2006 international codes would have a score of about 100. ENERGY STAR homes have HERS scores of 85 or lower, meaning they are built 15% more efficiently than what’s required by code. Existing homes may be around 130, though I have seen scores well over 200 for really inefficient homes. Net-zero energy homes score zero or lower. I published a case study on the Habitat for Humanity “Legacy Home” in 2010, where they had a -16 HERS because the home produced more energy than it used.

hers11 What Is A HERS Score?

The rating shown is from my 1954 built block-construction home, renovated in 2005. Apparently, the previous owners did a pretty good job when retrofitting and didn’t skimp on insulation. We have not had another rating since installing PV solar panels this winter.

HERS scores may be required to be posted in future home sales so that buyers know exactly what they are buying and would be a good indicator of how much it may cost to operate the home. I’ve heard other countries like Germany have been doing this standard practice for years. The cost of HERS ratings vary by company so it’s important to shop around. Quotes for my own home were between $250-$450. Unfortunately, the $99 energy audits offered in Arizona do not include a HERS score but can be added and done at the same time as long as the professional is both BPI and RESNET certified. You can find qualified professionals to hire at:

If your home has a good HERS score it can be a great marketing tool when you are ready to sell. As a buyer, you also have 10 days to inspect a home before proceeding. Why not order an energy assessment if you plan to live in and operate the home over the next 5-30 years? After all, energy costs are anticipated to continue to rise.

The Arizona MLS, mortgage industry, and green home building industry all recognize the HERS index and it is been searchable within the MLS since 2009. It will be more and more common as new home builders and savvy investors and homeowners lead the way in making HERS indexes a standard disclosure.

The lower the HERS score, the better

Lot 52 Ellington Gait (805 Carousel Court) has a HERS Score of 62.


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