Solar Reflectance Of Roofing Materials

The more waves that are bounced back into the atmosphere the higher the solar reflectance of the asphalt roofing shingle.

Solar reflectance of roofing materials.

Solar reflectance and thermal emittance are the two key material surface properties that determine a roof s temperature and they each range on a scale from 0 to 1. The solar reflectance index sri is a measure of the constructed surface s ability to reflect solar heat as shown by a small temperature rise. All roofing products must be certified and labeled according to the cool roof rating council crrc to comply with the standards. To meet leed requirements a roofing material must have a sri of 29 or higher for steep slope 2 12 roofing and a sri value of 78 or higher for low slope roofing.

Requirements and is calculated according to astm e 1980 using values for reflectance and emissivity. It is defined so that a standard black surface reflectance 0 05 emittance 0 90 is 0 and a standard white surface reflectance 0 80 emittance 0 90 is 100. The solar reflectance measurement ranges between 0 0 and 1 0 with 1 0 representing 100 reflectance with no absorption. The solar reflectance index is used for compliance with leed.

Heat island effect roof. Asphalt shingles with higher solar reflectance values can achieve energy star certification. Solar reflective shingles are designed specifically to reduce the absorption of the suns infrared radiation by reflecting ir rays off the surface of the roof thus not allowing the heat to be transferred to the interior of the structure i e. Emissivity is a material s ability to release absorbed energy.