The potential for reducing urban air temperatures and energy consumption through vegetative cooling

A network of 23 weather stations was used to detect existing oases in Southern California. Four stations, separated from one another by 15 25 miles (24 40 km), were closely examined. Data were strongly affected by the distance of the stations from the Pacific Ocean. This and other city-scale effects made the network inadequate for detection of urban oases. We also conducted traverse measurements of temperature and humidity in the Whittier Narrows Recreation Area in Los Angeies County on Sept. 8-10, 1993. Near-surface air temperatures over vegetated areas were 1 2 °C lower than background air temperatures. We estimate that vegetation may lower urban temperatures by 1 °C, while the establishment of vegetative canopies may lower local temperatures by an additional 2 °C. An increase in vegetation in residential neighborhoods may reduce peak loads in the Los Angeles area by 0.3 GW, and reduce energy consumption by 0.2 BkWh/year, saving $20 million annually. Large additional savings would result from regional cooling. t This workwassupportedby theCaliforniaInstituteforEnergyEfficiency(CW_.E) throughtheU. S.Departmentof Energy,undercontractDE-AC0376SF00098. _:Presentaffiliation:CapitalEnvironmentalEng. Corp.,Taipei,Taiwan,R.O.C.