Are You Living on a Heat Island?

Most people in metropolitan and urban areas are unaware that they are living on a heat island – an area marked by significantly higher surface and air temperatures than surrounding rural areas. There are several causes of heat islands:

• Replacement of the natural environment with pavements (especially asphalt) and buildings
• Reduced air flow between large buildings
• Heat from air conditioners, factories, and cars
• Weather conditions
• Location of city or town

According to the EPA, “cities with 1 million people or more can have air temperatures 1.8-5.4 degrees F warmer than surrounding areas” during the day and “as high as 22 degrees F” in the evening. Even cities with less than 1 million people often have higher temperatures of up to 10 degrees F than the surrounding areas.  Although inhabited by less than 1 million people, cities like Oklahoma City, Tulsa, and Lawton are potential heat island locations.

Frequently, heat islands are discovered using satellite imagery and measured according to the urban heat island index (UHII)[i].  An UHII study was conducted in Oklahoma in 2003[ii]. At 29.5 feet (9 meters), the air temperature was consistently 32.09-35.15 degrees F (0.5 -1.75 degrees C) warmer at the center of Oklahoma City than in surrounding areas.

Why do heat islands matter? Heat islands have devastating consequences for communities: they increase energy usage, exacerbate air pollution and greenhouse emissions, damage water quality, and are contributors to heat-related illness, even death. What can you or I do?

1. Encourage our state and local policy makers and legislatures by writing or calling them.

• To enact new tree and landscape ordinances
• To  establish new zoning codes such as parking lot requirements
• To reevaluate building codes to include green building standards

2. Increase tree and vegetative coverage, in your own yard, neighborhood, or community

3. Encourage businesses to install a green roof.
A green roof is simply a one that has a garden or vegetation incorporated as either a part of the roof or growing on top of it. The Cardinal Engineering building and the Winnie Mae House in Oklahoma City are great examples of a green roof top. For more information about green roofs visit www.greenroofs.org

4. Encourage governments and businesses to use cool pavements.
While regular pavements absorb and retain much of the sun’s heat, cool pavements reflect 5-40 percent of sunlight (there is no industry standard), and/or facilitate water evaporation. For example, one might use a lighter color of material to reflect the sun or use a pervious concrete to increase the permeability of the pavement .In addition to reducing the heat island effect, cool pavements also lower tire noise and increase road visibility at night.

5. Painting structures white or lighter colors

Currently, only 23 states have initiatives to reduce the temperatures and effects of  heat islands.   Oklahoma is not one of them. For more information on heat islands, visit the Environmental Protection Agency website.