White roofs can cool your homes and the planet

White roofs can cool cities

05 February 2010 CITIES can battle the "urban heat island" with paint. Highly reflective white roofs could cool cities by an average of 0.6 °C, according to a global simulation.

Dark city surfaces like roofs and roads absorb and radiate heat, leaving cities up to 3 °C hotter than surrounding areas. A team at the US National Center for Atmospheric Research in Boulder, Colorado, combined climate models with a simulation of how temperatures are modified by city landscapes.

They found that in a hypothetical world in which cities sported highly reflective white roofs, urban temperatures were on average 0.6 °C cooler than in cities with existing, mostly black roofing materials. In the real world, says lead author Keith Oleson, the benefits might be slightly less as rooftops get covered in dust (Geophysical Research Letters, in press). More >>>