Creating Change

The City of Phoenix Office of Sustainability, the Street Transportation Department, and Arizona State University (ASU) partnered together in this program, in conjunction with CoolSeal by GuardTop as the cool pavement supplier, and ViaSun Corporation as the asphalt contractor.

It is a water-based asphalt treatment that is applied on top of the existing asphalt pavement. It's made with asphalt, water, an emulsifying agent (soap), mineral fillers, polymers, and recycled materials. It contains no harmful chemicals and is compatible with traditional asphalt.


The Cool Pavement Pilot Program was created by the City of Phoenix Office of Sustainability, the Street Transportation Department, and Arizona State University (ASU) with the goal of improving the livability of the city by cooling down neighborhoods and reducing energy costs.

To launch the program, CoolSeal by GuardTop was applied to 36 miles of neighborhood roads and one public parking lot in the city of Phoenix in 2020.


Yes, the cool pavement coating is a lighter grayish concrete color. When applied, the material dries to a matte finish. Despite being lighter in color, cool pavement does not result in glare. It also meets or exceeds skid-safety requirements.

Cool pavement can be sprayed or applied with a squeegee, just like traditional surface treatments applied to city streets.

CoolSeal is a high-performance, water-based, asphalt emulsion sealcoat designed to achieve lower surface temperatures through its lighter color and reflectivity. CoolSeal meets Environmental Protection Agency (EPA) and LEED requirements of 33 percent reflectivity and can last longer than conventional sealcoats.

When looking at the material cost difference between the CoolSeal product and traditional black asphalt, CoolSeal runs about 60 cents per square yard higher. However, as Special Projects Administrator, Street Maintenance Division Rubben Lolly points out, the benefits will outweigh the difference in cost, considering the additional benefits of CoolSeal in terms of overall lifespan of the product, which will ideally last around seven years.

In addition, reducing the air temperature has the potential for big savings when it comes to energy bills. “A single degree Fahrenheit reduction in air temperature during the summer could save residential ratepayers about $15 million per year in avoided air-conditioning costs,” says David Sailor, Director of the Urban Climate Research Center at ASU.

In a virtual presentation and panel discussion on September 14, 2021, the City of Phoenix released the results of the first year of this innovative program. The study, performed by scientists at ASU’s Global Institute of Sustainability and Innovation, Healthy Urban Environments, and the Urban Climate Research Center, found that the reflective pavement surface temperatures of CoolSeal by GuardTop are considerably lower than traditional roadway pavement. Cool pavement coating reflects a higher portion of the sunlight that hits it, and because of this higher reflection, the coating has the potential to offset rising nighttime temperatures in the region.​
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So far, the study has revealed that the nighttime air temperature at six feet of height was on average 0.5 degrees Fahrenheit lower over cool pavement than on the non-treated surfaces.

In addition, cool pavement had an average surface temperature 10.5 to 12 degrees Fahrenheit lower than traditional asphalt at noon and during afternoon hours. Sub-surface temperatures averaged 4.8 degrees Fahrenheit lower in areas treated with cool pavement, too.

Researchers will continue working in partnership with the Phoenix City Council to launch the second phase of the Cool Pavement Pilot Program in the future. The next phase of the program will include continued reflectivity measurements and long-term performance testing for durability, bonding, and surface wear, while also assessing related environmental, health, and social implications.