Pervious Concrete and Mitigation of the Urban Heat Island Effect

Paved surfaces are large contributors to the urban heat island effect as they absorb and store energy during the day. There are many alternative pavements which are being considered for their environmental benefits with respect to stormwater runoff control. One of these is pervious concrete. Due to the potential insulating capability of its void structure it is theorized that pervious concrete will aid in abetting the urban heat island, although studies have shown that pervious concrete has a high surface temperature. This study compared pervious concrete of two different porosities to traditional concrete and traditional asphalt pavements. It was found that the surface temperature of the pervious concrete was higher than traditional concrete and could be adequately modeled based on a combination of solar reflectance, the lower mass at the surface and additional surface area caused by its unique void structure. It was found that the base temperature under the pervious concrete pavements remained similar to ‘cooler’ surface applications such as soil and lighter concrete, even with the higher surface temperatures, verifying the insulating capability of the pervious concrete during the daytime heating cycle. The rate of heat transfer for pervious concrete with 23% total porosity was found to be approximately 59% of the rate through traditional concrete for similar circumstances. Using pervious concrete instead of impervious pavement surfaces appears to be a viable method of not increasing urban heat island impacts while also benefiting from its stormwater management characteristics.