LA Painting Streets White to Reduce Urban Warming

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Public Domain. Bureau of Street Services "StreetsLA" /Department of Public Works/State of California

We already know that the urban heat island effect can significantly increase temperatures and worsen heat waves, even in neighboring cities. But what can communities do about it?

Cities like Louisville, Kentucky, have already been exploring large-scale tree planting as a way to cut down on heat build up, now LA is unleashing another potential tool against urban warming:

They are painting some of their streets—trial roads in all 15 council districts to be precise—white. (Actually, it's more like an off-white/gray—but the principle is the same.) By covering blacktop asphalt with a more reflective "cool pavement" treatment, LA Street Services claims they'll reduce temperatures on a summer afternoon by ten degrees or more. In fact, Curbed Los Angeles reports that a similar scheme in Encino reduced surface temperature on a parking lot by a whopping 25 to 30 degrees.

Of course, immediate localized surface temperatures are probably less important than how the build up of heat on hard surfaces impacts the overall urban microclimate, and associated energy use. And an EPA study on the subject suggests that covering 35% of LAs roads with reflective pavement could reduce average air temperature by a full degree fahrenheit.

Combine this approach with other measures like urban tree planting, cool roofs, returning parking lots to nature and electrified transportation (all LA's buses will be zero emission by 2030!), and you can begin to see how cities could significantly move the needle on urban heat islands.

And the even better news is this: Air conditioning contributes to the urban heat island effect too, meaning any immediate reduction in temperature should mean an additional benefit of less waste heat being dumped from buildings and vehicles too.