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.

Solar reflectance of roofing materials.

Heat island effect roof. 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 attic under the roof. 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.

Asphalt shingles with higher solar reflectance values can achieve energy star certification. The more waves that are bounced back into the atmosphere the higher the solar reflectance of the asphalt roofing shingle. The ages solar reflectance and thermal emittance requirements will vary depending on the slope of the roof climate zone and the density of the roofing product. The larger these two values are the cooler the roof will remain in the sun.

The solar reflectance measurement ranges between 0 0 and 1 0 with 1 0 representing 100 reflectance with no absorption. Requirements and is calculated according to astm e 1980 using values for reflectance and emissivity. 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. Emissivity is a material s ability to release absorbed energy.