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AAMA Submits Comments on ENERGY STAR 6.0 Regarding Skylight Criteria

September 30, 2013

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AAMA issued a response earlier this month on the final ENERGY STAR® Draft Specification that was released by the Environmental Protection Agency (EPA) in late July. The following details AAMA’s response in regards to ENERGY STAR skylight criteria development.

Skylight and Tubular Daylight Devices (TDDs)
AAMA continues to recommend that the EPA must take the necessary steps to separate TDDs and skylight criteria. Continuing to dismiss the overall benefits of daylighting and the energy savings realized by reducing the need for artificial lighting has created an ENERGY STAR program for skylights and TDDs that leads to prohibitive manufacturing costs while significantly decreasing the advantages of these products. Continuing to apply the same performance criteria to TDDs and skylights results in inaccurate comparisons and ultimately distorts and provides erroneous conclusions for builders and homeowners.

TDDs are suited for use in places where skylights use can be difficult. Their design and function differ to meet distinctive consumer desires, which justify separate treatment in the criteria.

AAMA asks EPA to recognize the following updates pertaining to TDDs:

  • AAMA requests that an interim Version 6.0 ENERGY STAR addendum be considered which includes separate qualification criteria for TDDs once new testing data is available for review in the next few months. NFRC has approved procedures for VT ratings for TDDs (NFRC 203), which will allow TDDs to meet emerging code requirements for minimum VT. A testing apparatus is currently under construction and should be available and accredited to this procedure beginning in early 2014. Also, proposals are being considered to modify NFRC’s size adjustment formula for TDD U-factors, which may affect those ratings as well.
  • Based on this new data, AAMA encourages a study evaluating light to solar heat gain ratios (LSG) relative to TDDs. The EPA needs to reevaluate assumptions that solar heat gain coefficient (SHGC) reductions do not affect daylight availability.
  • AAMA asks the EPA to justify the methodology used in calculating the percentage of qualifying TDDs based on the CPD review discussed in the comment 1 response. It is not apparent how the percentages can be added without knowing the numbers in each climate zone.
Skylight Criteria Development
EPA has not technically justified lower than IECC SHGC criteria for skylights in South and South Central zones. Window criteria in both zones is at code maximum; therefore, the same relationship should be applied to skylights resulting in SHGC criteria of 0.30.

The current 0.48 U-factor in both the Northern and North Central Zones disqualifies approximately 80 percent of double-pane curb mount skylights available today. Most of the qualifying models are not marketed nationwide, greatly limiting consumer choice when they need this type. A slight increase to a 0.50 U-factor maintains a 10 percent improvement over the 2009 IECC and even the Department of Energy’s (DOE) proposed 2015 IECC values of 0.55 and allows a wider range of such skylights to meet ENERGY STAR qualifications. The number of eligible products within the CPD would double from 6 percent to 12 percent and have an equivalent or slightly higher incremental cost increase.

Draft Criteria For Skylights
  U-Factor SHGC
Current ES Criteria EPA Draft Criteria DOE Proposed 2015 IECC AAMA
Current ES Criteria EPA Draft Criteria DOE Proposed 2015 IECC AAMA
Climate Zone Maximum
U-Factor U-Factor Maximum
Northern 0.55 < 0.48 0.55 0.50 Any Any NR Any
North-Central 0.55 < 0.48 0.55 0.50 0.40 < 0.35 0.40 0.40
South-Central 0.57 < 0.50 0.55 0.55 0.30 < 0.28 *0.20/0.25 0.30
Southern 0.70 < 0.60 Z1-0.75
0.65 0.30 < 0.28 *0.20/0.25 0.30
*Exception: Skylights may be excluded from glazed fenestration SHGC requirements in Climate Zones 1 through 3 where the SHGC for such skylights does not exceed 0.30.

The DOE has requested that 2012 IECC U-factor values of 0.55 for both the Northern and North-Central Climate Zones be maintained within the developing 2015 IECC. Additionally, it is assumed that qualifying skylights and TDDs will be incorporated into the ENERGY STAR “Most Efficient” program, so it is difficult to ascertain how the EPA will expect manufacturers to achieve further U-factor and SHGC revisions to meet any proposed “Most Efficient” Program criteria without considerably sacrificing the performance attributes and benefits of these products.


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