Rating System

LEED BD+C: New Construction, LEED BD+C: New Construction, LEED BD+C: New Construction, LEED BD+C: New Construction, LEED BD+C: Schools, LEED BD+C: Schools, LEED BD+C: Core and Shell, LEED BD+C: Core and Shell, LEED O+M: Existing Buildings, LEED O+M: Existing Buildings, LEED O+M: Existing Buildings

Rating System Version

v2 - LEED 2.0, v2 - LEED 2.2, v2 - LEED 2.2, v3 - LEED 2009, v2 - Schools 2007, v3 - LEED 2009, v2 - LEED 2.0, v3 - LEED 2009, v2 - LEED 2.0, v3 - LEED 2008, v3 - LEED 2009

Inquiry

Since SSc7.2 roof area calculations exclude skylights, parapets, equipment, paving, and other rooftop surfaces ineligible for EnergyStar consideration, we question whether the translucent tensile fabric structure covering portions of our Project qualifies as "roof" in SSc7.2 calculations. For our Project, the proposed fabric roof covers unconditioned outdoor space, but the same questions may apply on projects using similar products to enclose conditioned interiors. The manufacturer of the proposed tensile fabric system claims that their membrane meets EnergyStar reflectivity requirements and that they are pursuing California Cool Roof and EnergyStar ratings. On this basis, we included this area in our initial roof area calculations. However, the manufacturer has not submitted conclusive evidence supporting their claim. We received ASTM E408 test reports confirming their product\'s emissivity, but submittals have referenced ASTM E424 reflectivity tests, not the ASTM E903 & C1549 tests cited in EnergyStar\'s Eligibility Criteria. The manufacturer asserts that ASTM E424 test for visible light reflectivity is equivalent to E903. They have only submitted data for new materials, but they have not complied with EnergyStar\'s aged testing requirements. SSc7.2 Credit Requirements specifically refer to EnergyStar Eligibility Criteria and ASTM E903 tests for solar reflectance, noting that visible reflectance is irrelevant to Credit compliance. Past CIRs emphasize the requirement for aged testing and the need for all testing to conform to the specific, cited ASTM methods. However, these tests may be inapplicable to translucent materials, and such materials may not even qualify as "roofs" under EnergyStar Eligibility Criteria. EnergyStar\'s Eligibility Criteria define "roof surface" as, "The uppermost part of the roof system that is in direct contact with solar radiation", yet their list of "Qualifying Products" does not include light-transmitting roof materials such as glass, plastic, fiberglass, or fabric. All roof types defined in the Criteria appear to be opaque membranes, coatings, tiles, and shingles applied directly to structure. Both cited reflectivity tests, ASTM E903 and C1549, apply primarily to opaque membranes, referring to other test methods for translucent materials. [Measurements of reflectivity and emissivity alone may not accurately gauge heat-island effect at clear or translucent materials. Opaque roofs can only reflect solar radiation or convert it to heat. When considering translucent materials, one may need to deduct energy from transmitted light as well.] If the tensile structure counts toward our total Project roof area, but fails to achieve EnergyStar, one of the buildings on our campus will not meet the 75% EnergyStar/high-emissivity requirement. [All other buildings do comply, including the Main Building, whose EnergyStar roof makes up at least 87% of the total Project roof area. However, the Main Building\'s designer can only sign the Letter Template for his own scope. We had hoped that each building could comply independently, allowing each designer to sign SSc7.2 Letter Templates for each respective scope.] If we can exclude the tensile roof from the total Project roof area, all buildings will clearly comply. Can we omit light-transmitting materials, such as those described above, from SSc7.2 roof area calculations as we would skylights? If not, what tests, applicable to light-transmitting materials, will demonstrate EnergyStar equivalence of such materials? Finally, if one of our three Designer\'s scopes cannot demonstrate Credit compliance, can the Project still achieve the Credit based on Letter Templates from the remaining Designers?