Hashem Akbari, Dr. Rosenfeld’s colleague at the Lawrence Berkeley laboratory, says he is unsure how long it will take cool roofs to truly catch on. But he points out that most roofs, whether tile or asphalt-shingle, have a life span of 20 to 25 years.
If the roughly 5 percent of all roofs that are replaced each year were given cool colors, he said, the country’s transformation would be complete in two decades.
–Felicity Barringer, New York Times, “White Roofs Catch On As Energy Cost Cutters”, 7.29.09
Nice to have our highly trained, massively schooled Lab scientists here to explain those thorny percentage problems for us. I bet Mr./Dr. Akbari has a really cool white lab coat, too. With pens and stuff in the pockets.