Name: How Coating Roads Could Help Beat the Heat
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Concrete and asphalt make cities hotter, because they absorb the sun’s energy and re-radiate it as heat, even well into the night.

A pilot program in Phoenix, Arizona aims to cool the city by making the ground less hot.

How Coating Roads Could Help Beat the Heat

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Concrete and asphalt make cities hotter, because they absorb the sun’s energy and re-radiate it as heat, even well into the night.

A pilot program in Phoenix, Arizona aims to cool the city by making the ground less hot.

Tech & Engineering

How Coating Roads Could Help Beat the HeatPublished: June 21, 2023Narrator: Phoenix, Arizona: with little vegetation to begin with, the city is even hotter than the desert that surrounds it, so they must find a way to cool the city.David Hondula: Almost every summer, we have a hundred days or more over a hundred degrees. And regularly each summer we’re exceeding 110 degrees. Any time we can find hot ground and make it less hot, that will produce a cooling benefit with respect to the air temperature.Narrator: The idea is simple: recoat the roads with a special sealant that will reflect about 35 percent of the sun’s energy, which means less energy is absorbed by the asphalt and reradiated as heat. In 2020, the city launched a pilot program to cover 36 miles of roads in eight neighborhoods.David Hondula: Okay, so we’re going to take a reading with our infrared thermometer.Narrator: But does it work? Heat-sensitive images, taken from a helicopter, reveal a striking difference. The more reflective surface is as much as 16 degrees cooler. And, an M.I.T. study projects that it could lower the average temperature of some cities by two and a half degrees.David Hondula: Now we are seeing new approaches which are really exciting for cities all across the country. We could wind up with a city of the future that’s cooler than the one we have today.Brian Stone: We can substantially cool down cities in a relatively quick period of time, without major expenditures. And so that’s really good news.

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How Coating Roads Could Help Beat the Heat

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Support Provided By

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How Extreme Heat Overwhelms the Human Body

How Sewage Becomes Drinking Water

Weathering the Future