Research from Oregon State University describes how deep blue may be just as effective as white roofs in keeping the buildings cool. The researchers state that the sun’s rays don’t make objects warmer until they have been absorbed into the ground and get radiated as heat. So to keep a roof cool, you want to reflect the sun’s rays before it can be turned into heat.
Changing the chemical makeup of darker pigments can reflect as much of the rays as the common white roofs currently being used. The Oregon researchers mixed up and heated a bright blue pigment with manganese, yttrium and indium oxide that reflects the sun’s rays extremely well.
Cool Roof Color Choices Coming Soon
Other colors can be modified to be used in the cool roof tiles and the cost is nearly the same as asphalt or rubber roofing materials commonly used. The U.S. Recovery and Reinvestment Act funds are being spent for basic research into the new reflective pigments.
Cool roofs can reflect between 29 and 78 percent of the sun’s heat compared to 10 to 20 percent on conventional roofs. Construction of cool roofs is becoming standard procedure for new roofs, the Department of Energy calls for cool roofs to be incorporated whenever practical.
The Lawrence Berkeley National Laboratory’s Heat Island Group says an energy savings of $15 billion over 20 years, the average lifespan of a roof, for retrofitting 14,000 square miles of roofing.
This might be especially useful for apartment buildings that tower over flat white roofs. Tenants often complain about the bright white surface when looking out their windows.
