cool roofs improve comfort on hot summer days and reduce the amount of energy used for air-conditioning – thereby reducing energy costs and improving air quality. whitening flat roofs is a low-cost solution which, if implemented in certain cities across the globe, has been estimated to have the potential to offset the carbon emissions of 300 million automobiles.

in this video, renowned physicist and energy efficiency expert arthur rosenfeld discusses research at lawrence berkeley national laboratory (lbnl) that for the first time quantifies the reflective power (albedo) of urban surfaces that would be necessary to mitigate the urban heat-island effect and offset carbon dioxide emissions. other speakers discuss insulated and vegetated (“green”) roofs and how different types of cool roofs may be combined or integrated with solar-roofing systems, photovoltaics (pv) and/or solar thermal technology. more information is available at bit.ly/​coolrf