Research Findings: Concrete Pavements Make Urban Heat Islands Worse, Not Better!
Concrete pavement promoters have speculated for years that light-colored concrete pavements would help to mitigate the urban heat Island (UHI) effect. The UHI effect is a well-documented phenomenon that results in urban areas being warmer than their rural surroundings; what has not been field-proven, however, is the theory that light-colored pavements actually reduce the UHI effect.
University of California, Davis Research shows walls adjacent to concrete pavements become hotter during the day than walls adjacent to asphalt pavements.
New research by several universities is in fact showing that dark-colored pavements do more to mitigate the UHI effect than light-colored pavements. The National Center of Excellence for Smart Innovations at Arizona State University (ASU) is studying the impact of pavement characteristics on air temperature. The hypothesis is that if pavement color has no impact on air temperature at, for example, 5 feet above the pavement, then pavement color has no impact on UHI. Recently, Professor Kamil Kaloush provided a summary of the study's initial findings and stated, "Air temperatures at 3 and 5 feet above the [concrete and asphalt] pavement surfaces are similar (< 1˚F difference). The research team believes that factors such as wind speed, rain, and humidity may have a more significant role in air temperatures above pavements than pavement surface material type."
The findings from ASU's research were recently presented at the 2013 Transportation Research Board Annual Meeting in Washington, D.C. ASU's findings are paralleled by a similar study from the University of California at Davis, which concluded that air temperatures 1 foot or more above light-colored and dark-colored pavements were not significantly different. In fact, reflective pavements were shown to heat up adjacent buildings, actually increasing the UHI effect. The Alliance will keep you up to date as additional information is presented on these studies.