The desert oasis is often represented in movies as an island of cool green palms and a running spring or pool amid a sea of sand. The urban oasis is in some ways its opposite, a dark “heat island” whose temperature profile stands out from the cool greenery of the surrounding countryside.
Since 1985, a group of LBL researchers has been studying urban heat islands and ways to mitigate their high temperature. They have found that on a summer day, the average temperature in a typical American city is about 3 to 5 degrees F hotter than the surrounding area; they also estimate that air conditioning to cool cities from this effect accounts for 5 to 10% of urban peak electric demand. In Los Angeles alone, the additional electricity costs more than $100 million per year, not counting the costs of the added smog concentration caused by this heat.