LA is painting streets a lighter color to fight heat waves


Reflective gray paint absorbs less heat and is better at reflecting the sun’s energy. Photo courtesy of the City of Los Angeles.

No matter how hot it gets, Ryan Solomon takes a walk every day. Such is the life of a dog owner. But on his street in LA’s Palms neighborhood, the temperature doesn’t hit him quite as hard as it used to — even as the thermometer has started rising on the year’s first serious heat wave.

That’s because Vinton Ave., where Solomon lives, is covered in reflective gray paint. The City of Los Angeles has included the area in its Cool LA project, which targets certain neighborhoods to paint some streets a lighter color and plant more trees.

Solomon – like other dog walkers KCRW talked to in the neighborhood – has noticed. 

“I thought it was a silly idea until they did one half of the street before they did the other half,” he says. “And I was walking and it felt like a wave almost … like if you're on the Metro or something, and you step outside, and you get that breeze of cold air.”

Multiple cities across the Southwest continue to face excessive heat warnings, and climate change is making heat waves hotter, longer, and more frequent. The City of LA has plans to combat global warming by lowering local greenhouse gas emissions, and is also looking at how to make life in LA tolerable in the heat. That’s where the cool pavement comes in.

Over the past four years, the city has already lightened up the pavement on hundreds of miles of streets in Canoga Park, Sun Valley and Pacoima, and lined many of those miles with trees. They’re prioritizing neighborhoods with a lot of concrete and asphalt, and little shade. 

The City of LA estimates when the cool pavement is new, it reduces the surface temperature by as much as 15 degrees Fahrenheit. 

“Cool pavements work by having surfaces not absorb quite so much of that sun energy, and reflecting it back more quickly,” says UCLA Urban Planning and Geography Professor Kelly Turner, who has studied the program. Darker colors absorb more of the sun’s heat, and lighter colors are better at reflecting it.

But that’s not necessarily good news midday, because the reflection of heat actually makes the air above the street hotter. 

“If you were thinking about cool pavement and you wanted to put it in, say, a playground at a school, that might not be the best choice because a playground is going to be getting its most use around 1 p.m. or noon,” Turner says. 

Later in the day, however, the heat reduction is much more noticeable. Because the street didn’t absorb as much heat during the day, it doesn’t radiate stored heat throughout the afternoon, so it isn’t giving off that hot oven effect. 

In the afternoons, “when [residents] are walking, they will feel cooler and their pets’ paws will be cooler. And then it's a really successful implementation of an intervention,” Turner says.

Turner points out there’s another strategy to cool neighborhoods that’s far more effective than changing the color of the pavement: planting trees.

“It doesn't matter what surface you're looking at,” she says. “If they're sun exposed, they're all going to be way hotter than any of the surfaces shaded.”

That’s why the same streets in Palms that got a gray-wash are now also lined with saplings.

Palms resident Carolyn Anderson is happy to see them. She has little shade and no air conditioning.

“If the globe is heating up, if weather patterns are erratic, if we're needing to mitigate the change in climate, I don't think you can go wrong by having shade trees,” she says.

Trees may be effective, but it takes years for saplings to grow tall enough to provide shade. Plus, they’re not a silver bullet answer for a drought-ridden landscape.

“I don't think we have the carrying capacity for that in terms of our water supply,” says Jonathan Parfrey, founder of the LA-based nonprofit Climate Resolve, which partners with organizations and agencies like StreetsLA to combat climate change. Parfrey supports the pavement-lightening approach. “What are we going to do, given the fact that there's literally millions of miles of asphalt in the state of California? Why not put that to use?”

And after years of piloting these cool pavements, the city agrees.

“So many constituents are happy when we've applied cool paving in their neighborhoods.” LA’s Chief Sustainability Officer Ana Tabuena Ruddy says the city will continue bringing lighter, more reflective paint to new neighborhood streets. "We are funded for over $4 million. And so we will definitely deliver that in the coming fiscal year.”

Anderson, who lives in Palms, says she hasn’t noticed any cooling in her neighborhood yet, but she’s optimistic.

“I am trusting that paving the streets lighter makes a difference,” Anderson says. “I really really hope it does. We all need it to.”