Coating streets with white paint lowers temperatures

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Here’s why coating our streets white could help lower soaring summer temperatures

An innovative plan aims to lower the soaring temperature of LA’s streets. Representatives from the Bureau of Street Surfaces have covered 15 of the city’s streets in a light-coloured, asphalt-based substance. The home is it will lower sweltering temperatures, not only of the roads, but in surrounding buildings too.

2017 was the third hottest year on record and as temperatures continue to rise cities across the world are looking for ways to cool down. In Los Angeles, the pavement company GuardTop is coating streets white to help combat climate change.

Video Transcript

Narrator: 2017 was the third hottest year on record. And based on recent trends, it’s not getting cooler any time soon. Some researchers are asking, how can we stay cool? Especially in our cities. They’re typically hotter than rural areas. But why?

You can thank the urban heat island effect. On hot summer days, roofs, buildings and other urban surfaces can heat up to 90 degrees hotter than the air. This creates islands of heat. One of the biggest contributors to those islands, dark surfaces. Dark surfaces absorb all wavelengths of light and converts them to heat. So the surface gets warm. It’s why your mom told you not to wear black during a heatwave. Surface temperatures can reach up to 150 degrees. And since asphalt is an insulator, it traps that heat over the course of the day. Then at night when the air is cooler, the heat radiates away. Lighter surfaces, on the other hand, absorb fewer wavelengths and reflect the rest. That way, all that energy isn’t absorbed. And surface temperatures won’t rise as much.

So, would coating our streets white help cool down our cities? Enter Jeff Luzar, he’s the Vice President of Sales for GuardTop, a pavement company looking to cool off LA. Their solution? Coat the streets white.

Jeff Luzar: We’re seeing temperature difference right now of about, anywhere from about nine to 10 degrees, but again, the temperatures are pretty cool outside right now.

Narrator: When it’s hotter though, Jeff says the pavement could be up to 30 degrees cooler with the white coat.

Luzar: Some of the pilot programs that we’ve done last year with the Bureau of Streets and Services LA City, I know they are, as well as we are, taking a look at the surfaces, making sure they’re holding up, making sure they’re still doing what we said they were gonna do. And they are. And some of the neighbors are saying they do feel a little difference and this and that. If we can lower the temperatures by the ambient temperature outside by degree or two, it means a lot.

Narrator: That may not seem like a lot but a report by the Environmental Protection Agency suggests that a one and half degree change could make a huge difference. Los Angeles could save over $100 million per year in energy savings and smog reductions. But what is the coating made of? Most other pavements use coal tar. Some studies have been done and that where it’s showing that it could have some carcinogenic effects. But GuardTop says that its coating is made from recycled materials that don’t have carcinogenic additives.

Of course, LA isn’t the only warm city in the world. Other US cities are also considering coating their streets like Las Vegas. But officials there worry that it won’t stick due to an oily road mix it uses to combat dry climate. And in New York City, volunteers have painted seven million square feet of rooftops white, but that’s only 1% of the potential roof area. It’s clear that there’s still a lot of work to be done.

Luzar: I was never a big climate guy until we started getting into this product but when you see what differences one degree can make in climate change, it makes quite a bit of difference.

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