Research at Lawrence Berkeley National Laboratory suggests that if the 100 largest cities in the world replaced their dark roofs with white roofs, and if we changed dark blacktop roads to cement or other light-colored materials, we could offset more than 10 years of emissions growth.
Making roofs white is a win-win-win in the researcher’s minds because a white roof can reduce the air conditioning load of a building from 10 to 20 percent (while making it more comfortable), the reduced heat from buildings helps avoid the summer heat island effect in cities (while improving outdoor air quality), and the cooler roofs help cool the entire planet.
As we begin looking at the low-hanging fruit to combat climate change, regulations to mandate white roofs, particularly flat roofs, seems like step number one. California has mandated that flat roofs be white, primarily for the cooling benefits, since 2005. It would be good to see that regulation spread nationally.
