Solar Reflectance Of Roofing Materials

Residential and commercial roofing shingles slate roof ventilation roof underlayments asphaltic and tpo roof membranes.

Solar reflectance of roofing materials.

Link between energy savings and emissivity. Asphalt shingles with higher solar reflectance values can achieve energy star certification. The solar reflectance measurement ranges between 0 0 and 1 0 with 1 0 representing 100 reflectance with no absorption. One example is a metal wrench left in the sun which is hot to the touch because it has a low emissivity value.

The larger these two values are the cooler the roof will remain in the sun. Heat island effect roof. 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. How they can be made cool.

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

With the exception of a metallic surface most roofing materials can have emittance values above 0 85 85. Reflective surfaces are a form of geoengineering. Roofing shingles and materials plus factory certified roofers including ratings from real homeowners from north america s largest roofing manufacturer. The more waves that are bounced back into the atmosphere the higher the solar reflectance of the asphalt roofing shingle.

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. A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. 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.