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RESNET HERS® Index Ratings Soon to be Recognized in California

Jul 15, 2019

California dreamin’ on such a winter’s day – “California Dreamin’ (The Mamas & The Papas)

In the past, home energy ratings in California were different from the rest of the country, but this will soon change.

In California State law requires that home energy ratings be governed by the California Energy Commission (CEC). Ratings in the state are primarily used for compliance to the California energy code, Title 24.

Section 101.2.1 of RESNET’s Mortgage Industry National Home Energy Rating Standards provides that where state law governs home energy ratings, that state’s law shall preempt the RESNET standards.

The result has meant there were large differences in scores between a RESNET HERS Index rating and a California HERS rating.  This means that national production builders who rate and market their homes’ under RESNET’s HERS rating across the nation, cannot do so in California.

For the past five years the CEC and RESNET were in discussions on harmonizing HERS ratings between California and the rest of the nation. The effort is being driven by the desire of national production builders to use the RESNET HERS Index to market the energy efficiency of their homes in the state of California, just as they do across the rest of the country.

These discussions have resulted in a number of successes including the 2019 Title 24 Energy Design Rating (EDR) being very similar to RESNET’s HERS Index rating.  Both the EDR and the RESNET HERS Index reference home is based on the 2006 version of the International Energy Conservation Code.  See RESNET’s July 9, 2019 announcement “New California Energy Code Moves State to Closer Alignment to RESNET HERS® Index”.

The discussions also led to an agreement that national energy rating systems should be recognized in California, but CEC staff concluded that CEC HERS regulations need to be modified to make this happen.

On June 20, 2019, CEC formally recognized a RESNET true market research project that would quantify how RESNET HERS Index ratings could be used by builders to market the energy efficiency of their homes while not disrupting the CEC programs. The results of the research project could guide CEC staff in updating the CEC HERS regulations.

The outline of the research project will entail:

•The CEC CBECC-R development team building a HERS Index calculator module for CEC accredited rating providers to incorporate in their open source CBECC-R software.  This would only be allowed for use within the state of California

• RESNET partnering with the CEC accredited HERS Providers to incorporate HERS Index scores into their participating builder partnerships.


• Reports to the CEC on the progress of the effort including:

• How HERS Index Scores compare to the EDR scores in homes in California
• How the housing industry and real estate market responds to a HERS Score of homes for sale
• What next steps are needed to avoid confusion in the marketplace
This research project holds great promise in launching a truly national home energy rating system and allowing California builders to have their homes HERS Index rated and market their HERS Index scores in the state.  This also creates new business opportunities for California raters.Drew Bohan, the CEC Executive Director commented on the RESNET research project, “The Energy Commission understands that RESNET will be working with California’s HERS Providers during this pilot project, along with California production builders.  We support these partnerships and look forward to receiving the results of this pilot, which we agree should inform our future HERS II regulation update.”