Residential Roofing Solar Reflectance Index

The sr value is a number from 0 to 1 0.

Residential roofing solar reflectance index.

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 third metric used to measure the performance of cool roof coverings is called the solar reflectance index sri. It also must meet the specific solar reflectance thermal emittance and or solar reflectance index values defined by the specific energy code. Installing a cool roof can cut your energy costs while contributing toward a better environment.

It is defined so that a standard black reflectance 0 05 emittance 0 90 is 0 and a standard white reflectance 0 80 emittance 0 90 is. The guide to choosing a cool roof. Solar reflectivity or reflectance is the ability of a material to reflect solar energy from its surface back into the atmosphere. For example a standard black asphalt shingle would have an sri in the low single digits.

Solar reflectivity r solar reflectance index sri by color. The us department of energy defines the solar reflectance index sri as a measure of the roof s ability to reject solar heat as shown by a small temperature rise. The attic under the roof. By lessening the demand for energy it decreases carbon emissions that cause pollution.

Incorporates both solar reflectance and thermal emissivity in a single value. Solar reflectance index sri. The higher the sri the cooler the roof will be. Solar reflective shingles are designed specifically to reduce the absorption of the suns infrared radiation by reflecting ir rays off the surface of the roof thus not allowing the heat to be transferred to the interior of the structure i e.

A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. This measure is calculated from the tsr and te. Another method of evaluating coolness is the solar reflectance index sri which incorporates both solar reflectance and emittance in a single value. Furthermore it doesn t store as much thermal energy as an ordinary roof.

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. 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.