Westchester streetscape becomes a testing ground for heat-reflective coating

By Gabe Schneider

City workers apply a coat of cool seal next to Cowan Avenue Elementary
Photo by Maria Martin

In the face of global climate change and scorching summer heatwaves, Los Angeles is looking to keep neighborhoods cooler with a surprisingly simple solution: changing the color of the streets.

Last Saturday, the city’s Bureau of Street Services coated the block of West 77th Street between Cowan and Beland avenues with a light gray asphalt mix designed to reflect solar heat rather than absorb it.

City workers measured the initial street surface temperature at 115 degrees; after just one of two coats of the new cool seal, the temperature dropped to 99 degrees.

When traditional asphalt retains and radiates heat, it contributes to an urban “heat island effect” that can raise the temperature of a surrounding neighborhood by as much as 22 degrees.

“Asphalt, being darker in color, absorbs on the order of 80% to 95% of the sun’s energy, which results in substantial heating of the surface. In contrast, the original natural land surface of Los Angeles, before it was urbanized, reflected a substantial portion of the sun’s energy,” explained Jeremy Pal, a professor of civil engineering and environmental science at Loyola Marymount University.

According to a recent report from the U.S. Environmental Protection Agency, if the use of reflective pavement increased by 10% to 13% nationwide, air temperature could potentially drop by a degree, resulting in “lower energy use and [therefore] reduced ozone levels.”

Even if implemented on a large scale, however, the immediate benefits of cool coating remain local rather than global — impacting how we experience climate, not reversing climate change. But even that difference could save lives in the event of a devastating heatwave, said Pal.

“Urban heat islands have the potential to intensify heat waves by several degrees — particularly if they occur in spring and summer, thus severely exasperating health risks,” he said. “Reducing temperatures even a few degrees can reduce these risks.”

That’s justification enough for Rosy Lim, who lives nearby Westchester’s first coolcoated street.

“If it’s safer, I think it would be better for everybody if they paved all the streets like that,” she said.

Molly Nolan also contributed to this story.