Cool Pavement Pilot Program
Overview
The City of Phoenix Street Transportation Department partnered with the Rob and Melani Walton Sustainability Solutions Service at Arizona State University, and with researchers from various ASU schools and centers, to evaluate the effectiveness, performance and community perception of a new pavement coating designed to mitigate urban heat. Data collection and analysis for the cool pavement pilot project occurred across multiple neighborhoods from July 15, 2020 to July 14, 2021. Data gathered at varying times across days and months from each site allowed the research team to study the impacts of the pavement coating under various weather conditions. Numerous platforms and sensors were used to collect this data, with further analysis completed in ASU laboratories.
Outcomes
The pilot project produced several key findings, including the following:
- The surface temperatures of asphalt surfaces treated with the cool pavement coating were consistently lower than non-treated asphalt concrete at all times of day. The cool pavement surface temperature was, on average, 2.4°F lower at sunrise, 12.0°F lower at noon and 10.5°F lower in the afternoons.
- Sub-surface temperatures beneath the cool pavement coating were 4.8°F lower, on average, than temperatures beneath untreated asphalt.
- The cool pavement-coated surfaces displayed around 33-38% solar reflectivity when the coating was first applied. 10 months post-installation, solar reflectivity ranged from 19-30% across the eight test neighborhoods. This decline in reflectivity leads to a less significant decrease in surface and sub-surface temperatures. Untreated asphalt, for comparison, absorbs more solar radiation and has a consistent reflectivity of 12%.
- Mean radiant temperature, which represents the average human’s total radiant heat exposure when walking on the treated surfaces, increased by an average of 5.5% due to higher surface reflectivity.
Project partners
- City of Phoenix Office of Sustainability
- City of Phoenix Street Transportation Department
- Phoenix City Council
Cool pavement in the media
From road coatings to a sweating manikin, these ASU research projects are helping Arizonans keep their cool
March 03, 2025 | ASU News
The heat isn’t going away. And neither are sprawling desert cities like the metro Phoenix area. With new summer records being set nearly every year — 2024 was the warmest year on record for Phoenix — it has become increasingly urgent…
Second study says Phoenix’s ‘cool pavement’ has positive effect so far
Oct 17, 2024 | AZ Family
The city of Phoenix’s innovative plan to lower the surface temperature of asphalt streets during summer months got a boost Thursday night, when researchers from Arizona State University revealed that use of cool pavement…
North Phoenix outdoor mall partners with ASU to test ‘cool pavement’
Sept 17, 2023 | 12 News
In the brutally hot dry, desert, it’s not uncommon to endure weeks on end of enduring 110-plus temps during the hottest times of the year, which is why many city leaders and communities are continually looking for better ways…
Cool pavement
The Rob and Melani Walton Sustainability Solutions Service is home to a number of projects that address the world’s most pressing sustainability challenges. Familiarize yourself with our ongoing work by taking a look at our full projects list.