Our project\'s operational requirement mandates large paved areas in excess of 30% of the 490,314 s.f. site area. Our goal is to specify a previously developed concrete mix that complies with ASTM C1549 and has been previously tested and presented to USGBC on a prior project. The test results for this material yielded a Reflectance Average Value of .41 for the concrete paving material. The previous test results on three concrete pavement samples ranged from 0.38 to 0.45 Reflectance (Albedo) Values. The testing lab that conducted the reflectivity testing for the prior project has the following accreditations: IAS-ES TL-189, State of Florida TST 1556, Metro-Dade 01-0727.03, and CRRC. This C.I.R. is requesting confirmation that USGBC will accept documentation certifying that the concrete mix utilized on our project is equivalent to the previously utilized and tested mix and that actual laboratory testing will not be required on a project by project basis.
The applicant is inquiring if test data obtained for a different project can be used to document the albedo/reflectivity of the concrete mix used on this project if the same mix is used. It would appear that the previous project being referenced was a LEED NC v2.1 project since the test data supplied relates to albedo/reflectivity. It should be noted that with regards to paving materials, LEED NC v2.2 SSc7.1 requires that paving materials have a Solar Reflectance Index (SRI) of at least 29. The SRI value of a material takes into account both a material\'s reflectivity and emissivity. It is acceptable to use the previous test data as documentation of the materials reflectivity assuming the concrete mix is identical and the test data was done in accordance with ASTM E 903, ASTM E 1918, or ASTM C 1549. This reflectivity value can then be used in conjunction with the material\'s emissivity value to determine the material\'s SRI value. To document the reflectivity value, the applicant should provide the test data along with documentation demonstrating that the concrete mixes used in both cases are identical. It should also be noted that when a range of values is provided, as is the case above for the material\'s reflectivity value, the more conservative number should be used, not the average. Applicable Internationally.