Residential Roofing Solar Reflectance

Solar reflectivity or reflectance is the ability of a material to reflect solar energy from its surface back into the atmosphere.

Residential roofing solar reflectance.

Solar reflective shingles. Solar reflectivity r solar reflectance index sri by color. Owens corning asphalt shingle products labeled as cool are rated with the cool roofing rating council ccrc for solar reflectance and thermal emittance. The sr value is a number from 0 to 1 0.

The most well known type of reflective surface is the cool roof. Painting a metal roof can increase its solar reflectance and thermal emittance allowing it to achieve cool roof status. A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. 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. 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. Innate reflectance is measured on a scale from 0 to 1 with the latter being the highest level of reflectivity meaning it reflects 100 of all radiant energy coming in contact with it. All of these types of residential roofing products are now available with ir reflective color pigments which act to reduce the temperature of roofs and reflect heat away from the home.

Feature gaf proprietary color blends and enhanced shadow effect for a genuine wood shake look. Unpainted metals are typically good solar reflectors but poor thermal emitters so they rarely satisfy low slope cool roof requirements. Cambridge tm cool colors reflect a percentage. As you re shopping for your new roof look for the tag or label solar reflectance.

These shingles must have an initial solar reflectance of at least 0 25 and a three year solar reflectance measurement of at least 0 15. Reflective surfaces are a form of geoengineering. California s building energy efficiency standards for residential and nonresidential buildings title 24 part 6 contains requirements for the thermal emittance three year aged reflectance and solar reflectance index sri of roofing materials used in new construction and re roofing projects. Meet the prescriptive solar reflectance and thermal emittance requirements according to the 2016 title 24 standards are rated by the cool roof rating council and meet the cool roof requirements of the los angeles green building code find out more about title 24 here.

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. This is a requirement in some energy codes.