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Standard Development Process For HERS Impact and Increased Deliberations

Jul 1, 2022

RESNET Modifies Its Standard Development Process to Allow The Disclosure of Potential Impact on HERS® Index Scores of Proposed Standard Amendments and Increased Industry Vetting and Amendment Implementation Deliberations


The past 10 years have been a period of dynamic change for RESNET standards. Standards have evolved as energy use technologies and building performance modeling in HERS rating software have advanced and as new opportunities for use of HERS ratings have expanded. At times the change has seemed rapid and change has been difficult to keep up with.

RESNET has taken and continues to take steps to make change more predictable and to improve the energy rating industry’s ability to adapt.

RESNET has developed energy rating standards since 1995. In 2012 RESNET decided that to gain wide acceptance of its standards and to advance the recognition of energy ratings in building energy codes, mortgage financing, and other new and emerging opportunities it would develop its technical standards through the American National Standards (ANSI standards) process.

RESNET moderates the impact of the ANSI/RESNET changes by controlling their adoption for its HERS Rating Index. ANSI/RESNET standards do not apply to the HERS until adopted by the Mortgage Industry National Home Energy Rating Standards (MINHERS) as referenced standards. This approach also allows RESNET to amend the ANSI/RESNET standards, (e.g., ANSI/RESNET/ICC 301), to adapt them specifically to the HERS Index ratings.

RESNET recognized in 2016, that the implementation of changes to its standards happening at random times caused difficulties for the HERS industry, builders, and energy efficiency programs using the HERS Index. To address this issue RESNET responded by establishing January 1 and July 1 as default effective dates of MINHERS addenda via Addendum 32 in 2018. The criteria were modified and expanded to include Voluntary Compliance Dates, Mandatory Compliance Dates, and Transition Periods via Addendum 43 in 2019. Compliance was first benchmarked to the building permit date and then expanded by the second addendum to include additional options.

By 2021 it was recognized there was still stress resulting from standards revisions and RESNET has responded by revising its Standards Development Policy and Procedures.  

The most recent changes focus on the determination of the impact standards revisions have on the HERS Index rating. Standard Development Committee (SDC) 300’s advisory committee on calculations is now charged with estimating the potential impact on HERS Index Scores when reviewing amendment proposals. Its estimates will be reported to SDC 300 and disclosed with public review drafts. When amendments are final and updated rating software is available the impact of the changes will be analyzed more precisely by RESNET staff. The results will be provided to the Standards Management Board for consideration when setting Voluntary and Mandatory Compliance Dates.

Some changes to RESNET standards are more urgent than others and will require the industry to adapt quicker. However, better information on the impact of changes on the HERS Index and the ability to establish appropriate Transition Periods will moderate disruption of builders’ production decisions and marketing as well as impacts on energy efficiency programs that rely on HERS ratings.

As RESNET’s technical standards evolve RESNET will continue to be sensitive to how change impacts the rating industry. The HERS Index must remain nimble and responsive to change in the face of evolving competition and opportunity as well but it will continue to be sensitive to the rate and how much change the industry can effectively absorb.