What to Know
- The asphalt-based sealant with an added cooling property reflects more than 35 percent of sunlight.
- Can cool the surface temperatures down by up to 25-30 degrees.
- The sealant costs between 50 to 60 cents a square foot.
The temperature in the City of Angels has become a matter of public health.
“In Los Angeles, we actually have heat-related deaths even in the winter,” said Greg Spotts, assistant director of the Los Angeles Department of Public Works Bureau of Street Services.
Spotts said the amount of pavement covering LA has created an urban heat island effect that is making the city even hotter than its surrounding areas.
“So the environmental community came to us at the Bureau of Street Services saying that there are some new kinds of treatments for the pavement that would make it absorb less heat from the sun,” Spotts said.
The city chose a white-colored coating called CoolSeal made by GuardTop. GuardTop sales and marketing manager Davis Koleas explained CoolSeal is an asphalt-based sealant with an added cooling property that reflects more than 35 percent of sunlight—compared to traditional black pavement that absorbs and traps the sun’s heat even after the sun sets.
“On a hot day, say an 85-90 degree Fahrenheit day, traditional black asphalt can get up to 165 degrees,” Koleas said. “It’s [CoolSeal] designed to cool surface temperatures down by up to 25-30 degrees.”
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In phase one of LA’s pilot program, the city has covered one block of roadway in each of its 15 council districts with CoolSeal.
In Silver Lake, its CoolSeal white coating has turned a bit grey from the black tires driving over it the past year, but you can still feel the difference in the surface temperature.
“So right now, we’re standing on the untreated black asphalt that was originally on this street, and it’s about 130 degrees Fahrenheit,” Spotts said while reading the temperature on his Thermometer gun pointing at the ground. “So now let’s walk over to this coated area—we’ll walk a little bit into it since there’s, you know, transfer across that line there, and here it’s 118. So right now it’s a 12 degree difference.”
Spotts said neighbors he’s spoken with are supportive of their streets being painted, and their pets also seem to approve the change.
“Interestingly, dogs seem to notice this coating,” Spotts said. “You’ll see them walk away from the crosswalk and across the grey part. The local dogs have learned that it’s cooler on their paws.”
This effort to reduce road heat and decrease the amount of heat-related deaths is just one way the city of Los Angeles is trying to combat urban heat. This project is part of a larger effort to be more sustainable for the future.
Spotts said his end goal is to have multiple solutions to lowering the temperature in their city.
“The pavement hasn’t changed in 50 years, and so it’s good for all of us to open our minds to some new possibilities,” Spotts said.
The next step for the city of Los Angeles is to cover all of the roads in one neighborhood with CoolSeal. That way they can find out if the cooler road temperature will make the overall temperature in that neighborhood cooler as well.
As for how much it costs, there wasn’t a clear answer. Koleas said it costs between 50 to 60 cents a square foot—depending on the age and quality of the asphalt it would cover (because older asphalt would require more CoolSeal).
Spotts said the city is also considering covering bike paths to see if cyclists find it more pleasant.
