Facts collected to date: 1. The Cool Roof Rating Council (CRRC) is the referenced document for this point in the LEED Reference Guide v2.0. 2. The CRRC does not identify the testing system used per each roofing system listed 3. I have been in discussion with one roofing company about a product listed in the CRRC with a 0.9 emmissivity. i have received a cut sheet on the product stating the emmissivity rating as 0.9. 4. Further investgation revealed that the test used was the ASTM C1371 not the ASTM E408. The roofing company states that the E408 is a more expensive test and with the same results, so most will use the C1371. 5. The CRRC states that the two tests "can produce results that differ from each other by 0.05." 6. This same discussion has been repeated with many of the roofing manufacturers, with the same results. Questions: 1. How critical is the use of the ASTM E408 rating test for emmisivity versus the ASTM C1371 test to obtain LEED approval of the roofing system used? 2. Is it enough to submit a cut sheet highlightng the 0.9 emmissivity for LEED compliance of this point?
Your first "fact" is incorrect. LEED references the Energy Star roofing criteria for reflectivity and ASTM E408 for testing emissivity. ASTM C1371 will not be accepted in place of ASTM E408 to test emissivity. SSc7.2 CIR dated 12/15/2003 states that "To meet the requirements, 75% of the roofing material must meet both the reflectivity requirements of Energy Star based on testing using ASTM E903 and the 0.9 emissivity requirement based on ASTM E408 testing. The metrics used for this credit are currently being reviewed for potential revision in Version 2.2. Until a revised requirement is approved through USGBC membership ballot, the current credit language must be upheld." Documentation provided to support achievement of this credit must indicate both the emissivity value and testing method used. If the cut sheet includes this information, then it is sufficient for your LEED submittal. Please note that ASTM C1371-98 is used for determination of emittance of materials near room temperature, making it a more appropriate test method for the emissivity of interior materials such as foil and other reflective insulations. ASTM E408 measures total normal emittance of surfaces. ASTM itself states that "this Test Method (C1371) does not supplant