Energy-efficient roofing materials are becoming more popular,
but most commercially available products are geared toward the
low-slope sector. However, research and development are taking
place to produce "cool" residential roofing materials.
In 2002, the California Energy Commission asked Lawrence
Berkeley National Laboratories (LBNL), Berkeley, Calif., and Oak
Ridge National Laboratories (ORNL), Oak Ridge,Tenn., to collaborate
with a consortium of 16 manufacturing partners and develop "cool"
non-white roofing products that could revolutionize the residential
The commission's goal is to create dark shingles with solar
reflectances of at least 0.25 and other nonwhite roofing
products—including tile and painted metal—with solar
reflectances not less than 0.45. The manufacturing partners have
raised the maximum solar reflectance of commercially available dark
products to 0.25-0.45 from 0.05-0.25 by reformulating their
pigmented coatings. (For a list of the manufacturers, see
"Manufacturing partners," page
Because coatings colored with conventional pigments tend to
absorb invisible "near-infrared" (NIR) radiation that bears more
than half the power of sunlight (see Figure 1), replacing
conventional pigments with "cool" pigments that absorb less NIR
radiation can yield similarly colored coatings with higher solar
reflectances. These cool coatings lower roof surface temperatures,
reducing the need for cooling energy in conditioned buildings and
To read the article in its entirety, please log in or register (registration is free).
Log in or register for FREE access to this article and other Professional Roofing online content.