| | | | | Illustration by Emily Sabens/The Washington Post; iStock | | What if you could send heat from any surface on the planet into space? Well, you can. It's called passive cooling. And we can apply it to everything from roofs to vehicles. This week, I explored cool roofs. | |  | | Years ago, I walked onto the roof of the Palo Alto Research Center. The nondescript beige building in Silicon Valley, known for groundbreaking technology, is the birthplace of the mouse, laser printer and Ethernet. That afternoon, researchers were sending heat from the roof into space. It was my first encounter with passive cooling technology — materials designed to reflect or radiate energy back into the world. Despite the scorching temperatures on the roof, when I touched a box covered with white material, it felt inexplicably cool, as if I was touching a steel refrigerator door. I've often thought about it on hot summer days, after getting into my car or baking at home: Why isn't everything covered in it? In theory, passive cooling could lower energy bills, save lives and even cool the planet itself. It's finally catching on. | | What is a cool roof? Builders and architects have painted roofs in light colors to reflect sunlight for millennia. New products rival the performance of white material in dozens of colors, including black. For example, 3M's cool roofing granules, the knobby texture in asphalt shingles, can reflect up to 25 percent of solar energy, even in dark colors, about twice as much as conventional shingles. Over the past few centuries, however, asphalt and tar have blackened the urban landscape, says NASA. Why is this a problem? These materials, while durable, waterproof, and cheap, inadvertently turn cities into urban heat islands. This is deadly. There were more than 10,000 heat-related deaths in the United States between 2004 and 2018, according to the Centers for Disease Control and Prevention, a toll expected to worsen as temperatures rise. | | Should I get a cool roof? Well, most pay for themselves. In hot climates, it can take less than a year, estimates the Environmental Protection Agency. Here are some steps to follow: - Use an online calculator to estimate your energy savings by analyzing your climate, insulation, building type and energy prices. Dow offers a Cool Roof calculator; a second is available from Oak Ridge National Laboratory.
- Talk to a roofer. Most are now familiar with these materials. It pays to come prepared: Browse the array of materials in the Cool Roof Rating Council's database.
- Use this rule of thumb from Ravi Kishore, a research engineer at the National Renewable Energy Laboratory: "The hotter and drier the climate, the bigger the benefit," he says.
Not everyone needs a cool roof, he says. But as climate change advances, dark roofs will raise everyone's thermostat because of the urban heat island effect. Expect more cities to follow the example of Los Angeles by mandating passive cooling technology. In the end, a cool roof is for everyone. | |  | | Did you know I read all your emails? Be part of the Climate Coach community. Write with what you'd like to see in this newsletter: climatecoach@washpost.com. | | Was this email forwarded to you? Sign up here to get The Climate Coach in your inbox every Tuesday and Thursday. | | See you on Thursday, Michael Coren, Climate Coach | | | | | | | | | |
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