If you’re considering building a custom green home, then you’re already thinking about sustainability and living in a house that’s better for the environment. You may have even heard reference to HERS ratings and why it’s useful to have your new high-performance home rated.
But what is the HERS rating system, and what do HERS ratings mean?
Understanding the HERS Index System
The HERS Index—short for Home Energy Rating System—is a nationally recognized scoring system used to measure a home’s energy performance. It was developed by the Residential Energy Services Network (RESNET) and introduced in 2006. Since then, it’s become the gold standard used by the building industry to score and measure the energy efficiency of a home—over 4.5 million homes have been HERS rated.
So, what is the HERS Index, and what does a HERS score mean? The HERS rating of a home is calculated by looking at two factors:
- How much energy the home is expected to use, based on building envelope, insulation, HVAC, and more
- How much renewable energy the home generates, such as from solar PV systems
The result is a numeric score—the lower the HERS score, the more energy efficient the home is. Here’s how the scale typically breaks down:
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130: The rating of the average resale home
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100: A home built to current building code standards (RESNET’s baseline home)
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50: A home with a HERS score of 50 uses 50% less energy than the baseline home)
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0: A Net Zero Energy home that generates enough energy annually to offset the energy used
Older, inefficient homes can score well above 130, while on the opposite end of the spectrum, it’s actually possible to have a negative HERS score, meaning that your home generates more energy through renewable sources than it uses. Homes built by BPC Green Builders are often rated 50 or lower—we’ve built a number of homes with negative HERS ratings (somewhat ironically, they’re called Positive Energy Homes).
In short, think of a HERS score as your home’s energy report card, verified by a professional HERS Rater.
What Is a HERS Test?
A HERS test involves a comprehensive home energy audit performed by a certified HERS Rater. This includes:
- Blower door testing for air leakage
- Duct leakage testing (if applicable)
- Inspection of insulation levels and installation quality
- Evaluation of windows, HVAC equipment, lighting, and water heating systems
The HERS Rater uses energy modeling software to generate the HERS Index score. The final report shows how the home compares to a baseline code-built home and outlines specific performance data.
The Benefits of Getting a HERS Rating for a Home
1. Certified Third-Party Verification of Your Home
A HERS report for your custom green home not only confirms your new home’s energy efficiency but also the quality of its build as well.
2. Healthier, More Comfortable, and Greener Homes
Homes with low HERS ratings come with all the advantages of a truly high-performance home, including higher indoor comfort and healthier, cleaner air as well as environmentally-friendly construction.
3. Lower Home Ownership Costs
Living in an energy-efficient home isn’t just better for the planet—it saves money, too. The lower your home’s HERS Index score, the lower your annual energy bills.
For example, reducing a home’s HERS score by just 10 points can result in hundreds of dollars in annual energy savings. Those savings increase significantly over the lifespan of the home.
Why HERS Ratings Are Important for New Green Homes
When designing and building a green home, BPC Green Builders can work with the homeowner to create a target HERS rating. We’ll then plan and build accordingly, aiming to hit that number through smart design, airtight construction, and efficient systems.
But the home’s actual score will be based on a final inspection and diagnostic testing performed by a certified third-party HERS Rater.
All BPC homes are HERS rated and certified, and many of them scored in the 40s, 30s, or even below zero on their HERS test, meaning they have been verified to well exceed industry standards for energy performance!
You can see examples of these homes, their features, and how they achieved their exceptional energy scores in our project gallery.
Learn more about HERS ratings and other green building standards. Contact BPC Green Builders online today to talk to the leading custom green home builder in CT & NY.
