Facts and Current Solutions
Heat Island Facts
- Urban Heat Islands can make it hotter in the city
- Both the air and city surfaces can be hotter.
- Solar heat adds to surface temperatures.
The warmest air is found downtown.
Because most of the buildings and parking lots are downtown, and it is usually the center of the city.
Dry, dark surfaces absorb more sunlight.
Dark surfaces such as asphalt roads and parking lots absorb more sunlight and become much warmer than light-colored surfaces
Certain structures and city geometry favor heat islands.
These are thick walled buildings that are slow to warm and cool, and so they store a lot of heat.
Storm Water runs off instead of being filtering through the ground.
Covering the ground with waterproof surfaces makes it dryer and keeps the rain from cooling it down. Also the storm water doesn't filter through the ground and it carries pollutants directly into streams and waterways.
- Storm Water run off can cause flooding
Solutions for Heat Islands That Already Exist
Another alternative to traditional roofing materials is a rooftop garden, or "green roof". On hot summer days, the surface temperature of a vegetated rooftop can be up to 90 degrees Fahrenheit (50 degrees Celsius) cooler.
Cool paving does not get as hot. There are two types of cool paving materials: lighter-colored materials and porous materials (porous means the water goes through). Lighter-colored materials reflect the sun's energy and stay cooler. Lighter-colored materials come in shades of white, beige, light gray and terra cotta.
Plant trees and plants
Increasing the cover of trees and vegetation in a city is a simple and effective way to reduce the Urban Heat Island Effect. Trees provide a wide range of other benefits, from increasing property value to reducing storm water runoff.
Use less energy
This reduces smog
Light Colored Roofs
Light colored roofs reflect the sunlight back up and do not absorb as much heat.
Some things we can't change:
Some of these factors, like prevailing weather patterns, geography, and pollution transported from up-wind regions, are largely beyond the influence of local policy. However we can affect all of the ones listed above.