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Cool Pavement Pilot Program

Cool Pavement Pilot Program

The City of Phoenix Street Transportation Department partnered with the Rob and Melani Walton Sustainability Solutions Service at Arizona State University and researchers from various ASU schools and research centers to evaluate the effectiveness, performance and community perception of a new pavement coating applied to mitigate urban heat effect. The data collection and analysis occurred across multiple neighborhoods and at varying times across days and/or months over the course of one year (July 15, 2020–July 14, 2021), allowing the team to study the impacts of the surface treatment under various weather conditions. Numerous types of platforms and sensors were used to collect data, with further analysis completed in ASU laboratories. The research produced a number of key findings, including the following:

  • Surface temperatures of the treated asphalt surfaces (CP) were systematically lower than non-treated asphalt concrete across all times of day. The CP surface temperature was, on average, 12.0°F and 10.5°F lower than the asphalt concrete at noon and afternoon hours (ranging from 9–16°F lower), and 2.4°F lower, on average, at sunrise.
  • Sub-surface temperatures beneath the CP were lower (4.8°F on average) than beneath the untreated asphalt concrete surfaces.
  • Surface solar reflectivity of the CP was around 33–38% when installed and declined over time. The solar reflectivity 10 months after installation ranged from 19–30% across the eight neighborhoods. These reductions in reflectivity can result in less decreases in surface and sub-surface temperatures. For comparison, an untreated asphalt concrete surface had a consistent reflectivity of 12%, hence absorbing more solar radiation.
  • Mean radiant temperature, representing a human’s total radiant heat exposure walking on the surfaces, was increased at noon and afternoon hours by approximately 5.5°F, on average (ranging from 2.6 to 9.2°F higher), due to higher surface reflectivity.


    • Phase One

    Phase Two