Policies to reduce heat islands: Magnitudes of benefits and incentives to achieve them
A "Cool Communities" strategy of lighter-colored reroofs and resurfaced pavements, and shade trees, can directly lower annual air conditioning bills in Los Angeles (LA) by about $100 million (M), cool the air in the LA Basin (thereby saving indirectly $70M more in air conditioning), and reduce smog exceedance by about 10%, worth another $360M, for a total savings of about $0.5 billion per year. Trees are most effective if they shade buildings; but they are still very cost effective if they merely cool the air by evapotranspiration. Avoided peak power for air conditioning can be about 1.5GW (more than 15% of LA air conditioning). Extrapolated to the entire US, the authors estimate 20GW avoided and potential annual electricity savings of about $5–10B in 2015. To achieve these savings, they call for ratings and labels for cool materials, buildings` performance standards, utility incentive programs, and an extension of the existing smog-offset trading market (RECLAIM) to include credit for cool surfaces and trees. EPA can include cool materials and trees in its proposed regional "open market smog-offset trading credits".