At the recent CRRC Technical Committee meeting there were three presentations on the development of predictive aged solar reflectance formulae for different types of roof products. The equations are based on CRRC directory data of initial and aged solar reflectance values. The predictive formula for painted metal showed the best fit to a linear equation and had the least non-compliance. Overall, aged painted metal roofing also showed the best retention of the initial reflectance values compared to all other types of roofing products.
At the same meeting, the CRRC technical committee approved the removal of the exception for metal profiles in the CRRC-1 program related to high profile testing using ASTM E1918. This removal means that product profiles other than standing seam, corrugated and agricultural do not have to be measured for solar reflectance using the E1918 method. ASTM E1918 has no precision and bias in the standard and has been found to be very eratic and non-reproducible due to the large number of test variables.