Recently, CoolSeal’s Maria Koetter hosted “Beating the Heat: ASU’s Cool Pavement Study, Year 2 Results” as part of the Cool Communities, Healthy People Webinar Series. During the session, researchers shared the latest findings from the City of Phoenix’s Cool Pavement Pilot Program, which kicked off in 2020 with the application of CoolSeal to 36 miles of neighborhood roads and a parking lot. The goal of the program, which began when the City of Phoenix Street Transportation Department and Office of Sustainability teamed up with Arizona State University (ASU), was to cool down neighborhoods and save energy costs.
In 2021, Initial findings from the first phase of the Cool Pavement Pilot Program showed that CoolSeal cool pavement had an average surface temperature 10.5 to 12 degrees Fahrenheit lower than traditional asphalt at noon and during the afternoon hours. The study also revealed that sub-surface temperatures averaged 4.8 degrees Fahrenheit lower in areas treated with CoolSeal, helping to extend the life of the road.
Phase 2 Results
Then, in 2022, the City of Phoenix and ASU researchers, led by Dr. Jennifer Vanos, Associate Professor for ASU’s School of Sustainability, continued the program by performing repeated as well as new tests on CoolSeal 2.0 in “Phoenix Gray”, a heat-reflective coating created by GuardTop in response to Phase 1 results.
Building on the 2020 findings, Phase 2 results confirmed that CoolSeal's 38% reflectivity effectively reduced surface temperatures up to 12 degrees Fahrenheit, keeping roads cooler than regular asphalt. CoolSeal reduced subsurface temperatures over 9 degrees Fahrenheit in the summer. The air temperature above the CoolSeal coating was also cooler overall, especially after sunset. In addition, Phase 2 results demonstrated that CoolSeal reflected less UV radiation than traditional asphalt, reducing potential exposure.
As for the long-term benefits of CoolSeal, the Phase 2 results confirmed that CoolSeal kept the pavement cooler below the surface, which ultimately helps roads last longer, requiring less maintenance needs and costs. The study also suggested that the coating is ideal for residential streets and parking lots.
The Future of Urban Development in Phoenix
Moving forward, the City of Phoenix plans to take these findings and integrate them into future heat resilience strategies, including cool pavement expansion. According to Ryan Stevens, Engineering Manager for the City of Phoenix Street Transportation Department, the team has applied CoolSeal to more than 100 miles of roadway so far, and is looking for more locations to come this year. In addition, the City’s Cool Corridors Program will continue investing more than $1.4 million annually to add shaded structures, trees, and shaded bus stops, with the goal of improving pedestrian comfort.
Upgrading heat-resilient infrastructure is also on the City’s agenda, including upgrading roofs and public spaces with heat-reflective materials. The City of Phoenix also plans to expand emergency response efforts for extreme heat events.
More natural shade is another heat resilience strategy in the works. In fact, the City plans to plant more trees and implement shade policies to help cut down on heat absorption and improve air quality.
"The results from Phase 2 reaffirm that CoolSeal is making a meaningful impact in reducing urban heat and enhancing pavement longevity," sums up Cool Seal Sustainability Director, Davis Koleas. "We’re excited to learn from these findings and continue refining our technology to further support heat resilience efforts in Phoenix and beyond. As cities look for innovative ways to combat rising temperatures, we remain committed to improving CoolSeal to maximize its effectiveness and long-term benefits for communities."
