The January 1, 2027, mandatory compliance date (MCD) for ANSI/RESNET/ICC 301-2022, including Addenda A, B, C, and E, is approaching. To help the rating community prepare, RESNET® will publish a series of HERS® IQ articles explaining the upcoming changes and providing practical guidance for Rating Quality Assurance Providers, HERS Raters, Rating Field Inspectors (RFIs), and HERS Modelers. Background The original MCD for ANSI/RESNET/ICC 301-2022 was January 1, 2026. However, members of the rating community reported significant changes in HERS Index scores and requested additional time to evaluate the effects and prepare for implementation. In response to this feedback, RESNET postponed the MCD until January 1, 2027. The additional year provides organizations and individuals an opportunity to evaluate the updated calculation methods, train staff, revise procedures, and communicate anticipated changes to builders and other clients. If your organization has not yet begun preparing, now is the time to start. The rating community also raised concerns about the new requirement to specify wall orientation. In response, RESNET approved Addendum 98 on May 15, 2026. The addendum makes the specification of wall orientation voluntary until further notice. Upcoming HERS IQ Articles Over the next several months, RESNET plans to publish articles addressing: Revised modeling and field practices for HERS Raters, RFIs, and HERS Modelers required for ANSI/RESNET/ICC 301-2022 How to evaluate changes and communicate effectively with builders The results of RESNET’s impact study These articles will focus on practical steps the rating community can take to support a smooth transition. Software for Evaluating ANSI/RESNET/ICC 301-2022 The following software options support calculations under ANSI/RESNET/ICC 301-2022 and may be used to evaluate representative projects and existing templates: Ekotrope: Use Version 5.1 or later. REM/Rate: Select the applicable standard version at the bottom of the Rating Information screen. EnergyGauge USA: Use FL Code version 9 or later once released, or test with the public beta. When conducting comparisons, confirm that the correct standard version is selected. Consider testing several representative projects, including different climate zones, foundation types, HVAC systems, ventilation strategies, and construction specifications. Before registering a rating, users should also confirm that they are using an approved production version consistent with current RESNET requirements. Previous Impact Studies RESNET’s software accreditation team completed a limited software impact analysis comparing results under ANSI/RESNET/ICC 301-2019 and ANSI/RESNET/ICC 301-2022. The analysis included Ekotrope, EnergyGauge USA, and REM/Rate. Because the study used a limited group of building configurations and climates, individual projects may experience changes outside the ranges identified in the report. Ekotrope has also published two impact studies: The first study addresses changes associated primarily with Addenda A and B. The second study addresses additional changes associated with Addenda C and E. These studies can help rating professionals identify which building characteristics and modeling inputs may produce changes in HERS Index scores. RESNET’s upcoming impact study will be more comprehensive than the previous studies. It will evaluate a broader range of home types across all climate zones and include a variety of equipment types and efficiency levels. This expanded scope will provide the rating community with a clearer understanding of how ANSI/RESNET/ICC 301-2022 may affect HERS Index scores under different building and equipment configurations. The findings will help rating professionals identify common trends, anticipate potential impacts, and focus their own testing on the projects most relevant to their markets. Conclusion Successful implementation will require more than installing an updated software version. Rating organizations should begin testing representative projects, identifying changes that may affect workflows or HERS Index targets, training staff, and discussing potential impacts with builders and other clients. Rating Quality Assurance Providers should also consider how the transition may affect quality assurance procedures, documentation, and technical support. HERS Raters, RFIs, and HERS Modelers should become familiar with the new inputs and calculation methods before the mandatory compliance date. Starting now will allow time to identify questions, make necessary adjustments, and support an orderly transition to ANSI/RESNET/ICC 301-2022 on January 1, 2027. Next Standards Update Following this transition, the next edition of the standard, ANSI/RESNET/ICC 301-2028, is not scheduled for implementation until 2029, providing the rating community additional time to adapt before the next standards update. For questions contact technicalsupport@resnet.us
