A brief overview of the benefits of cool roofs.  Solar reflective “cool” roofs save energy, money, and CO2 when applied to air-conditioned buildings; improve comfort when applied to unconditioned buildings; and offset CO2 via global cooling (negative radiative forcing) whether or not the building is conditioned. They also relieve strain on the electrical grid by reducing late-afternoon peak power demand. Widespread use of cool roofs can lower outdoor air temperatures, further reducing the need for cooling energy, as well as improving air quality and human health by slowing the formation of smog. Over the 20 year service life typical of roofing, a national cool roof campaign could save 5.7 quad of net primary energy with a present value of $33B.