Arizona State University researchers are working with the city of Phoenix on a pilot program studying the use of "cool pavement" to reduce heat island effect, a phenomenon that raises temperatures in urban areas covered by asphalt and concrete.
According to ABC 15 Arizona, Phoenix is applying cool pavement coating to nine sites in different areas, from shaded streets to open lots. The applications are expected to be completed by the end of the month.
The Environmental Protection Agency says normal paving materials can reach temperatures of 120 to 150 degrees Fahrenheit during peak summer and transfer excess heat into the air. Lowering the surface temperature can provide comfort and reduced energy costs to residents sheltering from extreme heat.
When used in a parking lot, for example, the cool pavement temperature was 129 degrees Fahrenheit, whereas the asphalt next to it was within the 150 degree range.
Heat island effect is a “major factor” in both day and nighttime temperatures, according to the article, and a potential health hazard. Reducing surface temperature can also lower air temperature.
There are two basic categories of cool pavement. Reflective cool pavement has a lighter color and chemical properties that turn sunlight back toward the atmosphere. Evaporative pavement relies on rainwater seeping into its porous surface, and then cooling the pavement during slow evaporation. The choice is based on whether a city gets rain during its hottest months, or is in a dry climate.
Source: Tampa Bay Times & ABC 15 Tampa
