Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall.
Today, we’re going to talk about painting roofs white. Some experts say white shingles could lower electricity bills and cool down hot cities. So, should you make the switch?
Megan Hall: Here to tell us more are Luci Jones and Fatima Husain from our Possibly Team. Welcome, Luci and Fatima!
Luci Jones: Hi, Megan!
Fatima Husain: Hello!
Megan Hall: So, why would someone want to paint their roof white?
Luci Jones: Well, your typical roof is grey, black, or brown. And these dark colors absorb a lot of heat from the sun.
Fatima Husain: White roofs, on the other hand, reflect a lot more of that incoming sunlight.
Megan Hall: How much more?
Luci Jones: Check this out—white roofs can reflect up to 90% of sunlight while black surfaces like asphalt can only reflect about 4%, meaning they absorb the rest of that sunlight as heat.
Megan Hall: That seems like a big difference.
Fatima Husain: Sometimes, that difference is helpful. During the colder months, darker roofs capture incoming heat from the sun, so you don’t have to use as much energy to heat your home.
Luci Jones: But during warmer months, dark roofs can make life pretty uncomfortable.
Fatima Husain: When they absorb all that extra light, they can warm up your house, which means you’re likely to use more air conditioning.
Luci Jones: And, unless your electricity comes from 100% renewable sources, cranking up your AC adds more carbon dioxide into the atmosphere.
Megan Hall: So, should we all get white roofs?
Fatima Husain: Not so fast — it isn’t a one-size-fits-all fix.
Luci Jones: Let’s zoom out a bit. When we talk about black roofs capturing more heat, we’re not just talking about one house. The more dark surfaces you have in one place, the hotter it gets.
Fatima Husain: So, this tends to be more of a problem in cities, where there are lots of dark roads and rooftops right next to each other.
Luci Jones: It can actually get so warm that scientists have given these places a special name: urban heat islands.
Fatima Husain: For example, a place the size of New York City can be about 1 to 5 degrees Fahrenheit warmer than the nearest countryside.
Megan Hall: So could white roofs bring down the temperature in these areas?
Luci Jones: New York seems to think so! The government there is working to cover black roofs with white reflective paint all around the city.
Arianna Williams:
So we’ve been cooling the city for about 10 years. And in one year we aim to paint a million square feet. That’s about 13 soccer pitches.
Fatima Husain: That’s Arianna Williams, the co-supervisor for the New York City CoolRoofs program, talking in an informational video on their website.
Megan Hall: She thinks that white paint can really make a difference?
Luci Jones: She does! Arianna actually demonstrates this by using an infrared thermometer to measure the temperature of a black roof on a hot day…
Arianna Williams:
And that’s reading about 167 degrees. And when I pointed over here to the white–it reads it’s 116 degrees now. And that’s only the first coating of the paint.
Megan Hall: Wow, that’s huge!
Luci Jones: It is! Scientists say white roofs could help us avoid the most extreme effects of climate change in urban areas, like heat waves.
Megan Hall: Ok, so I’m dying to know: Should I get a white roof?
Fatima Husain: Well, the answer depends on where you live.
Luci Jones: If you live in a dense city or parts of the country where it’s warm for most of the year, you could save a lot of electricity by painting your roof white. Not to mention, you’ll be a lot cooler!
Fatima Husain: But if you live in a less populated place where you use heating more than air conditioning, it might not be worth it to ditch your dark roof.
Luci Jones: White roofs aren’t the cure-all for climate change, but if you live in a place that fits the bill, they can be an effective way to reduce your greenhouse gas emissions.
Megan Hall: Got it! Thanks, Luci and Fatima!
That’s it for today. For more information, or to ask a question about the way you recycle, use energy, or make any other choice that affects the planet, go to the public’s radio dot org slash possibly. Or subscribe to us wherever you get your podcasts.
Possibly is a co-production of the Institute at Brown for Environment and Society, Brown’s Climate Solutions Initiative, and the Public’s Radio.
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