Solar Reflectance Of Roofing Materials

Metal roofs are available with natural metallic finishes oven baked paint finishes or granular coated surfaces.

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. 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. 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.

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. Residential and commercial roofing shingles slate roof ventilation roof underlayments asphaltic and tpo roof membranes. Using solar reflective shingles and solar reflective roofing products that reflect ultraviolet and primarily infrared radiation will reduce damage caused by u v and heat degradation. Roofing shingles and materials plus factory certified roofers including ratings from real homeowners from north america s largest roofing manufacturer.

Link between energy savings and emissivity. Scientists use a number between 0 and 1 or 0 and 100 to express emittance. Unpainted metals are typically good solar reflectors but poor thermal emitters so they rarely satisfy low slope cool roof requirements. The sr value is a number from 0 to 1 0.

A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. Heat island effect roof. Reflective surfaces can deliver high solar reflectance the ability to reflect the visible infrared and ultraviolet wavelengths of the sun reducing heat transfer to the surface and high thermal emittance the ability to radiate absorbed or non reflected solar energy. Asphalt shingles with higher solar reflectance values can achieve energy star certification.

With the exception of a metallic surface most roofing materials can have emittance values above 0 85 85. Energy star requires an initial sr value of 0 25 or higher for steep slope 2 12 roofs and 0 15 or greater after three years. Reflective surfaces are a form of geoengineering.