Urban Heat Island

Mar 9th, 2011 | By | Category: Youth Blog

On a warm summer day, a city can be 6-8F warmer than its surrounding areas. Scientists call these cities urban heat islands. The higher temperatures in urban heat islands increase air conditioning and raise pollution levels. Urban heat islands are not only uncomfortably hot, they are also smoggier. Smog is created by photochemical reactions of pollutants in the air. These reactions are more likely to occur and intensify at higher temperatures. Higher ambient temperatures in heat islands also increase air conditioning energy use. As power plants burn more fossil fuels, they increase both pollution levels and energy costs. In Los Angeles, we estimate that about 1-1.5 gigawatts (GW) of power are used to compensate the impact of the heat island. This increased power costs the Los Angeles ratepayers about $100,000 per hour, about $100 million per year.

Measures to cool heat islands are simple and have been known to human beings for ages: reflective surfaces and trees. Light colored roofs reflect solar radiation and reduce air-conditioning use. The Heat Island Program estimates that by 2015, the full-scale implementation of reflective surfaces and vegetation will save the nation about $4 billion per year in reduced cooling energy demand.

**I found all this information at http://eetd.lbl.gov/HeatIsland/ The Heat Island Program is jointly funded by the U.S. DOE (Program Manager: Mark Decot) and the U.S. Environmental Protection Agency (EPA).

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