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Welcome to the latest installment in our Home Certification 101 series. In our first post, we described the what and why of certification for your energy-efficient or high-performing home. Since then, we’ve explored the ins and outs of Pearl Certification and other certifications and home scores. Today, we’re talking about the Home Energy Rating System (HERS®) Index.

To find other articles in this series, go to our blog and search “Home Certification 101”. Keep up with new posts by signing up below for our newsletter.

HERS Index: A Tool for New Homes

The most straightforward way to calculate home energy use would be to review a year’s worth of energy bills and tally actual usage. But for newly constructed homes, that’s not an option.

Enter the HERS Index. Designed by the Residential Energy Services Network (RESNET®), the HERS Index is primarily used to calculate energy use for newly built homes.

The HERS Index home score models the energy use of an “average” homeowner based on the home’s physical characteristics, including exterior walls, attic spaces, windows, ductwork, heating and cooling systems, and thermostats.

Think of the miles per gallon (MPG) stickers you see on new cars at a dealership. You can compare cars’ MPG estimates — and you can do the same with homes’ HERS scores to quickly evaluate their energy efficiency. Unlike MPG ratings, lower HERS scores are better.

How Does the HERS Index Work?

A certified RESNET Home Energy Rater first conducts an in-depth home energy performance assessment. “It paints an extremely detailed picture of every asset in that home,” says Pearl Certification expert Corey Bressler, who works closely with both raters and homeowners. “All that data — the U-values, R-factors, mmBTUs, and more — isn’t really homeowner-facing, though.”

The rater compares that data against a reference home — a computer-modeled home the same size and shape as the actual home but built strictly to 2006 energy-efficiency standards. They translate that comparison into a single score.

The reference home scores 100 on the index. The lower the actual home scores in comparison, the more efficient it is compared to the reference home. The HERS Index website provides two examples:

  • “A home with a HERS Index Score of 70 is 30% more energy efficient than the RESNET Reference Home.”

  • “A home with a HERS Index Score of 130 is 30% less energy efficient than the RESNET Reference Home.”

You might be used to 100 being the top score. That’s not the case here — but there’s plenty of room for improvement if your home scores 100. You can explore the HERS Interactive Tool to better understand what different scores mean for your home and your annual energy savings.

Related Post: What's a Home Energy Audit and When Do I Need One?

How Does the HERS Index Compare to Home Certification?

As we’ve discussed earlier in this series, certification is the process of evaluating a home and demonstrating that it meets specific criteria. Some certifications focus on a single aspect of home performance; ENERGY STAR® home certification, for instance, evaluates how efficiently a home uses energy. Other certifications define home performance criteria across multiple attributes. For example, Pearl Certification’s criteria relates to energy savings, comfort, health, and home value.

Certifications for newly built homes, including ENERGY STAR, LEED®, and the National Green Building Standard (NGBS), incorporate the HERS Index into their criteria for energy efficiency.

Related Post: What Is Home Certification and What Can it Do for My Home?

How HERS Index Score and Pearl Certification Work Together

Pearl factors in the HERS score when certifying newly built homes — and helps communicate the value of the HERS score to homebuyers, real estate agents, lenders, and appraisers. Pearl can also capture the value of HERS in existing homes, similar to how Pearl promotes and communicates the value of the U.S. Department of Energy's Home Energy Score and/or ENERGY STAR or WaterSense product ratings. 

“The HERS score gives you the big picture, and the full report does a great job collecting data,” Bressler says. “As part of the Pearl Certification process, we comb through the rater’s full dataset. We then highlight why the home performs well. We show homeowners, appraisers, and real estate agents the value of those high-performing features.”

If your home has a HERS Index score, why pursue Pearl Certification?

“When you get a HERS rating,” Bressler explains, “you get a wealth of data … but it represents a single point in time..” In contrast, he says, “Pearl is a living record of your home’s high-performing features. We integrate your original HERS rating and guide you as to how to keep improving. Two years later, you might add info about new appliances to your home’s record via our Green Door app. Five years later, you might add details about new insulation.”

Ensuring that your home’s value is visible to the market is another reason.

RESNET cites a 2017 study that demonstrates a connection between lower HERS scores and higher home values: “Energy-efficient HERS-rated homes sell for a premium anywhere from 3.5% to upwards of 9%.” The report itself calls the HERS Index score “a potential starting point to obtaining higher sale prices” but notes that turning potential into reality requires clear documentation and communication. That is exactly how Pearl Certification helps you get the most from your HERS score.

What’s Next?

Whether or not you have a HERS score, you can learn more about Pearl Certification and sign up for the award-winning Green Door app to start your home’s living record. You can also connect with qualified builders who work with Home Energy Raters and learn how to keep improving your home.

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