Final 2010 Energy Star Criteria Issued by DOE

April 7, 2009

With two notable changes from the most recent draft, the U.S. Department of Energy has released its final revised criteria for the Energy Star Windows, Doors and Skylight program, set to go in effect January 4, 2010.  In the final critiera, DOE will treat all doors the same, whether they swing or slide, and retain tubular daylighting devices within the program.

Both those changes had been supported by many in the industry, including both the American Architectural Manufacturers Association and the Window & Door Manufacturers Association.  Recommendations from various parties for further revisions in the Energy Star climate zones, adjustments to U-factor and SHGC requirements within those climate zones, and special criteria for high-altitude products were not included in the final 2010 criteria.

The change in doors represents a category shift for sliding glass doors, and means all doors follow the door criteria and the window criteria only applies to windows, explains Richard Karney, Energy Star program manager, in his letter to stakeholders announcing the final criteria. "Stakeholders suggested it would be easier for consumers to understand the separate criteria for doors if they applied to all doors and left only windows in the windows category," he states.  "The Department’s analysis showed that no significant savings would be lost by transferring sliding glass doors to the door category."

Questions about manufacturers' ability to get tubular daylighting devices rated and certified by  the National Fenestration Rating Council were one of the reasons DOE had considered dropping them from the Energy Star program, Karney's letter notes. Since the last draft criteria report, NFRC has clarified that manufacturers can recertify their products under an old simulation procedure, and therefore DOE decided to retain tubular skylights in Energy Star, as long as manufacturers show that the products' U-factors are rated under NFRC’s computer simulation procedure.

Tubular daylighting devices will get another look, however.  "Stakeholders have raised questions about the reliability of the test procedures for TDD U-factor and about the appropriateness of U-factor and solar heat gain coefficient to represent the energy performance of TDDs," Karney states. "For these reasons, DOE, with input from industry, will decide how best to represent TDD performance in the Energy Star program and will reevaluate TDD program participation as part of the research on Phase 2.

The revised Energy Star program requirements for windows, doors, and skylights go into effect January 4, 2010.  For partners to make the necessary changes to their product and marketing materials, there will be a transition period to full program implementation, scheduled to end on March 31, 2010, DOE notes.  More details on the transition will be provided in the coming months.

Karney notes that response to the final draft, eliminating finalized Phase 2 criteria, was welcomed by most stakeholders.  With Phase 2 criteria not set to go in effect for several years, DOE will begin further analysis later this year.


2010 Energy Star Qualification Criteria for Residential Windows, Doors & Skylights
Climate ZoneU-FactorSHGC
Swinging & Sliding Doors
≤ ½-Lite≤0.27≤0.30
> ½-Lite≤0.32≤0.30
Climate ZoneU-FactorSHGC
NR=No rating   

*Northern zone windows can meet prescriptive (1st row)
or alternative energy performance (2nd & 3rd row) criteria
to qualify for Energy Star.


New Energy Star Climate Zone Map