What would happen in Los Angeles if some roofs and pavements were resurfaced with light materials and the right kind of trees were planted in several communities?

Heat Island Group staff has been painting the town and shading its homes--all by computer simulation--to answer that question.

Staff scientist Haider Taha has run meteorological and air quality models for the Los Angeles basin. Taha divided the L.A. basin into hundreds of portions and estimated how much vegetation and reflective surfaces could be added to each location. Then he added trees and lightened surfaces in only about 15% of the possible areas. Summer temperatures at 3 p.m. dropped 6°F.

About 40% of the area in the LA basin is covered by buildings and roads which could realistically be made 30% more reflective during their next resurfacing. If this were done, summer temperatures in LA at 3 p.m. on August 27 could become 5 to 9°F (or 3 to 5°C) lower. The LA would consume 1/2 to 1 GW less in peak power, energy worth at least $100,000 per hour. Most areas would also have improved air quality, and the population-weighted average predicts an ozone reduction of 10 to 20% overall.

Because the rate of smog formation depends on temperature, this same model was used to estimate the effect on the region's smog, taking into consideration wind patterns, moisture, and other factors specific to the area. The results showed an overall reduction in smog by about 10%, the equivalent of removing three to five million cars from the roads. Similar modeling studies are being performed for Houston, Dallas, Chicago, Atlanta, Washington D.C., Baltimore, Philadelphia, New York City, Miami, Phoenix, and Tucson.

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