The U.S. Environmental Protection Agency (EPA) issued a letter yesterday requesting feedback from stakeholders about draft two of the Energy Star tubular daylighting devices (TDD) and revised skylight criteria.

Draft two specifications “[do] not include any revisions to address the issue [of addressing concerns previously raised for drafts one and two] because EPA believed the situation warranted further investigation,” according to Douglas Anderson, program manager for Energy Star for Windows, Doors and Skylights.

Last year, Anderson says the EPA learned that all TDDs would be “retested and the corresponding TDD listings in the National Fenestration Rating Council (NFRC) certified products director would be updated January 1, 2013 … Based on the findings of [an EPA] analysis and additional skylight information received during the draft two comment response period, EPA has modified the skylight criteria. Prior to finalizing the specification, EPA is seeking further stakeholder input on these proposed skylight criteria changes.” See the chart below for the proposed changes (noted in italics).

Table 3. Energy Efficiency Requirements for Skylights

Climate Zone U-Factor Solar Heat Gain Coefficient (SHGC)
Northern ≤ 0.45 ≤ 0.47 ≤ 0.35 Any
North-Central ≤0.47 ≤ 0.30 ≤0.35
South-Central ≤ 0.50 ≤ 0.25 ≤0.28
Southern ≤ 0.60 ≤ 0.25 ≤0.28


Proposed changes include having:

-the Northern Zone U-Factor maximum raised to 0.47 expand the number of Energy Star-qualifying double-pane curb-mount and double-pane deck-mount skylights as well as top-performing TDDs;

-any SHGC is now allowed in the Northern Zone. The EPA plans to complete further analysis of SHGC in the Northern Zone to address the issue and revise if needed;

-the North-Central Zone maximum will be raised to 0.35. The EPA plans to also complete additional research on this issue and revise if needed;

-the SHGC maximum will be raised to 0.28 in the South-Central and Southern zones, addressing feasibility and affordability concerns raised in the draft 2 comment response period.

Written comments must be submitted to the EPA by Friday, March 8, 2013, at EPA will post all of the comments to the Energy Star product development website for doors, windows and skylights unless the submitter requests otherwise.

EPA is also drafting responses to comments received about the draft 2 criteria and will release those comments at a later time. EPA plans to incorporate comments on this current request into the draft 2 comment responses.

The agency anticipates finalizing the specification in April, with a criteria effective date in early 2014.

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