Sri Value Of Roofing Materials

Solar reflectance index sri.

Sri value of roofing materials.

The higher the sri the cooler the roof will be. A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. Low slope roofs require an initial sr value of 0 65 or higher and 0 50 or greater after three year. The third metric used to measure the performance of cool roof coverings is called the solar reflectance index sri.

Incorporates both solar reflectance and thermal emissivity in a single value. 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. Sri can be calculated based on the pitch of a roof its weight its solar reflectance thermal emittance emissivity and its ageing characteristics.

Different roofing technologies have different sri values. 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. Recycled content of berridge metal. The solar reflectance index or sri is a calculation using the aged solar reflectance and thermal emittance measurements of the asphalt shingles materials.

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. Te is also measured from 0 to 1. This measurement can be used as an indicator of how hot shingles are likely to become when they re exposed to the sun. The higher the value the more heat the material emits.

Nb this definition means that it is possible to have materials with an sri of less than 0 or more than 100. Ref cool roof rating council solar reflectance index calculation worksheet. 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. 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.