Sri Index Roof

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.

Sri index roof.

Solar reflectivity or reflectance is the ability of a material to reflect solar energy from its surface back into the atmosphere. In many cases asphalt roofing shingle manufacturers use a shingle s third party certified aged sri value to demonstrate compliance with cool roof energy codes. Sri can be calculated based on the pitch of a roof its weight its solar reflectance thermal emittance and its ageing characteristics. It defines that the standard black is 0 which is most likely to absorb heat.

So just what is sri. Ref cool roof rating council solar reflectance index calculation worksheet. Solar reflectance index sri. Solar reflectance thermal emittance and solar reflectance index sri.

For instance the standard black has a temperature increase of. Cool asphalt roofing shingles are characterized by 3 key values. That s how the three terms listed above came into prominence as these measurements are how cool roofing is determined. Leed 2 2 sustainable sites credit 7 2 states that to receive one point building owners should use a roof with a solar reflective index sri of 78 over at least 75 percent of the roof s surface for roofs with slopes less than 2 12.

The sri is a calculation method using solar reflectance and thermal emittance values to determine the roof s overall capacity to refuse solar heat. The sr value is a number from 0 to 1 0. Solar reflectivity r solar reflectance index sri by color. Solar reflective index sri is important to understand when selecting a highly reflective roof coating that will help lower energy cooling costs.

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 is a unit developed by scientists at lawrence berkeley national laboratory. It stands for solar reflectance index which is a combination of two numbers a material s emissivity a measure of how effectively it rejects heat and reflectivity how much light energy it bounces back. Minimum sri for cool roof materials.

Incorporates both solar reflectance and thermal emissivity in a single value. The sri is a measure of the roof s ability to repel solar heat as shown by a small temperature increase. The selection of materials with a high sri can reduce indirect solar gain in buildings and reduce the urban heat island effect. What is solar reflectance index.

The standard white is 100 which is most likely to reflect heat. A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. This practice is prevalent in california.