The U.S. Environmental Protection Agency (EPA) released an update on its Energy Star Most Efficient program this week, including proposed criteria for 2024. As of June 2023, 2,651 models meet the current Most Efficient criteria across all categories, including 517 fenestration products produced by 48 partner companies. After a review of the data associated with currently recognized models, officials say they found that updates to the program’s criteria are needed “to recognize the best of Energy Star.” As a result, the agency is proposing changes for numerous categories, including sliding glass doors and windows. Criteria for skylights will remain unchanged in 2024.

For windows and sliding glass doors, no changes are proposed for the Northern and North-Central climate zones. In the South-Central zone, EPA proposes revising the requirements for solar heat gain coefficient (SHGC) from ≤ 0.25 to 0.23, aligning with new Energy Star Version 7.0 criteria set to take effect in October. At the same time, EPA proposes revising the current U-factor requirement of ≤ 0.20 and the SHGC requirement of ≤ 0.25 for the Southern zone to two equivalent energy performance options: U ≤ 0.21 and SHGC ≤ 0.23, or U ≤ 0.22 and SHGC ≤ 0.21. Changes to Southern zone requirements “may help expand the number of products available to consumers,” officials say. Proposed combinations of performance criteria for the Southern Zone have equivalent energy performance when using a Results and Assumptions table created for the Version 7.0 criteria revision analysis, they say.

The agency is also proposing the removal of North American Fenestration Standard/Specification (NAFS) Performance Grade ≥15 for doors, windows and skylights to help simplify criteria. Officials believe that the NAFS Performance Grade requirement “has not been shown to be beneficial in the product’s energy performance.”

EPA will provide additional information regarding the roll out of its Energy Star Most Efficient 2024 recognition with the finalization of criteria.

Stakeholders are invited to provide written comments on the new proposed criteria no later than August 21, 2023. They can do so by emailing

1 Comment

  1. I have walked through several manufacturers about this – it is very confusing, the IRA (inflation reduction act) and the tax credit vs. the Energy Star updates for October – and whether those qualify for the tax credit – thanks for putting the numbers down in writing in one spot – it’s helpful to everyone

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