Cool Roof Rating Council Unveils Addition to Directory

OAKLAND, Calif. — The Cool Roof Rating Council, a nonprofit that maintains a third-party rating system that tracks the radiative value of roofing materials, recently added the Solar Reflectance Index to its online directory of rated roofing products.

 

The SRI, which determines both the solar energy reflected by a roofing product and the product’s ability to radiate absorbed heat has been applied to some 2,000 roofing products already by the CRRC, says Sherry Hao, administrative manager for the organization.

 

"Say you’re a roofing product manufacturer and you have your product," says Hao. "You can send samples to one of our independent testing labs and they test for solar reflectance and thermal emittance, giving you a value for each. We’ll obtain those values from the test lab, combine them to determine the SRI, and post them on our directory."

 

The SRI value is set on a scale from 0 to 100, with 0 being a standard black roofing product and 100 a standard white. When determining the SRI value, solar reflectance weighs heaviest, largely because it is a measure of how much of the sun’s energy is reflecting off the rooftop, says Hao. By contrast, thermal emittance is the amount of absorbed energy that can be radiated outward. As such, products that run very hot when exposed to the sun can have a negative SRI value, while particularly cool materials can exceed a value of 100.

 

The CRRC tests for and maintains two SRI values in its online directory: an initially installed value for products right off the assembly line and a three-year value for products that have been in use for a period. 

 

"When a product sits on a roof for a number of years, its going to get soiled and weathered from exposure to the elements," describes Hao. "Technically the three-year value is more representative of the actual energy performance of that product."

 

According to the CRRC, the SRI is referenced by several green building programs and building code bodies, including LEED for New Construction, Version 3; California’s Title 24 standard; and the American Society of Heating, Refrigerating and Air-Conditioning Engineers’ standard 90.1-2007.