Sri Value Of Roofing Materials

Ref cool roof rating council solar reflectance index calculation worksheet.

Sri value of roofing materials.

This measurement can be used as an indicator of how hot shingles are likely to become when they re exposed to the sun. 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 sr value is a number from 0 to 1 0. The third metric used to measure the performance of cool roof coverings is called the solar reflectance index sri.

This measure is calculated from the tsr and te. Solar reflective shingles and solar reflective roofing membranes can be an important component in a building system designed to reduce overall building energy consumption and the impact the home or building has on the environment. A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. Nb this definition means that it is possible to have materials with an sri of less than 0 or more than 100.

Solar reflectance index sri. Sri can be calculated based on the pitch of a roof its weight its solar reflectance thermal emittance emissivity and its ageing characteristics. Asphalt coatings for example have aluminum pigments added to asphalt cutbacks and emulsions to give coatings solar reflectance index sri values of 21 30 on a scale of 0 100. 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.

Incorporates both solar reflectance and thermal emissivity in a single value. Low slope roofs require an initial sr value of 0 65 or higher and 0 50 or greater after three year. Recycled content of berridge metal. The higher the sri the cooler the roof will be.

Different roofing technologies have different sri values. Sri measures the roof s ability to reject solar heat defined such that a standard black reflectance 0 05 emittance 0 90 is 0 and a standard white reflectance 0 80 emittance 0 90 is 100. Te is also measured 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.