Solar Reflectance Index Metal Roofing

After 3 years the solar reflectance must be 0 15.

Solar reflectance index metal roofing.

Low slope roofs must have an initial solar reflectance of 0 65. A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. For an asphalt roofing shingle to be classified as a cool under the energy codes it needs to have a cool roof rating council crrc rating for thermal emittance and solar reflectance. It also must meet the specific solar reflectance thermal emittance and or solar reflectance index values defined by the specific energy code.

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. Only those roof products that meet the specifications. Solar reflectivity r solar reflectance index sri by color. Link between energy savings and emissivity.

A cool metal roof with high solar reflectance and high thermal emittance would have a lower surface temperature as compared to a roof with low reflectance and low emittance. Solar reflectivity or reflectance is the ability of a material to reflect solar energy from its surface back into the atmosphere. 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.

Recycled content of berridge metal. 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. 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. After 3 years the solar reflectance must be 0 50.

Steep slope roofs must have an initial solar reflectance of 0 25. Incorporates both solar reflectance and thermal emissivity in a single value. In the case of a cool metal roof a lower surface temperature translates into less heat gain into the attic space or living space below the roof. Solar reflectance index sri.

The sr value is a number from 0 to 1 0. The attic under the roof.