Sustainability
Calif. Community Tests Solar-Reflective Coatings To Reduce Urban Heat
Pacoima streets and lots are coated with a "cooling" application to reduce urban heat in a test pilot.
Photo courtesy of Pacoima Beautiful
A public-private research initiative in Pacoima, Calif., a Los Angeles section, is testing a new type of maintenance pavement coating across roads and hardscapes to improve longevity and mitigate urban heat. After promising results from the first phase, a second phase is now underway.
GAF, a Standard Industries company and one of the largest roofing and waterproofing manufacturers in North America, launched the GAF Cool Community Project, a community-wide research effort to understand the impact cooling solutions have on urban heat and livability and provide insights other cities can begin to implement. The company worked with Pacoima Beautiful and the Los Angeles Bureau of Street Service on the project.
Jeff Terry, vice president of sustainability at GAF, says there has been a lot of research done to mitigate urban heat, but no one has taken a complete community approach to doing it. He says this project began with researchers looking at all hard surfaces in the 10 square-block community, then installing solar reflective pavement coating on all roads and parking lots and playgrounds. “This project and the research associated with it is going to help us understand if we can truly reduce the ambient heat that is happening in this community,” he says.
The multi-phased project began in July 2022. Phase one focused on applying over 1.2 million sq ft of StreetBond DuraShield Invisible Shade solar-reflective pavement coatings across an 18-square block area of Pacoima in Los Angeles.
The coatings were applied to neighborhood streets, parking lots, a community basketball court and an elementary school playground. GAF partnered with climate scientists to measure the impact of the coatings, including air and surface temperatures, as well as the albedo, the measurement of the energy from the sun that is reflected.
Two newly installed weather stations, existing satellites from NASA, drone measurements, continuous mobile sensor monitoring, and point measurements are actively collecting data. A nearby control area is also being monitored. Findings after 12 months show that the cool pavement coatings reduced surface temperature by 10ºF on sunny days. The project team says that it also found that the coated pavements heated up slower and cooled faster than the uncoated area.
Photo courtesy GAF
Ambient air temperature was also reduced on average by 2.1°F during the daytime on sunny days and up to 3.5°F during the daytime of an extreme heat event, say project officials, adding that, overall, the coatings helped to reduce 25-50% of the urban heat island effect during temperature peaks.
“All the positive results have led to an increased demand from local residents for more coatings in public spaces, with residents sharing that it feels cooler in their neighborhood, and they can now go outside more and enjoy these shared spaces together again.” says Melanie Torres, community organizer at Pacoima Beautiful.
“The key figure for understanding cooling and the interventions that GAF provides is albedo,” says Eliot Wall, senior director of Pavement Solutions, GAF. “These solutions help through multi-metal oxides, reflecting infrared wavelengths to reduce the heat that is stored within these hardscapes.
Wall says on used streets such as Pacoima’s, the coating should last at least five to seven years before it needs to be retouched or reapplied. But if the coating is applied to a new road, it can extend its life cycle by up to nine years.
The Streetbond Durashield Pavement Coating is a two-component waterborne epoxy-modified acrylic coating. GAF says the proprietary mixture has properties that include flexibility, adhesion, color stability and chemical resistance that optimize the preservation of asphalt pavements while also protecting the pavement from the harmful effects of oxidation from UV exposure.
Manufactured in Phoenix, AZ, the coating comes in light, fun colors for recreational areas, and darker colors for streets. The coating can be applied directly on top of pre-existing asphalt using a held-held sprayer or out the back of a work truck with a spraying machine.
Phase 1 of the Pacoima project completed last October when the remaining 18 blocks of roads were covered with StreetBond. Phase 2, currently in the works, entails covering five residential roofs with Cool Roof solar reflective coatings. The cost of the project has not been tallied, says Wall, but GAF is donating materials and labor.
In addition to Pacoima, GAF has applied 10 million sq-ft of StreetBond DuraShield to Los Angeles streets as part of the city’s Cool Streets Program, says Wall. The company has also completed projects in San Antonio, Las Vegas, and Phoenix.
Looking to the future, Wall says GAF is working with a handful of cities across California but can’t name them until the projects are officially secured. He says the coating season is between April and October and he expects to have several more projects lined-up by then.
“Pacoima was the first of its kind and we are exploring opportunities in other hot cities,” adds Wall. “About 77 percent of roads in the US are residential and what we are seeing as future opportunities is integrating into existing pavement maintenance budgets that cities already have to treat with products such as a slurry coat or a sealcoat, and instead using Durashield.”
