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Atlanta is embracing a cheap, effective way to beat urban heat: 'cool roofs' (grist.org)
submitted 1 year ago by to c/urbanism@slrpnk.net
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Walk outside into 100-degree heat wearing a black shirt, and you’ll feel a whole lot hotter than if you were wearing white. Now think about your roof: If it’s also dark, it’s soaking up more of the sun’s energy and radiating that heat indoors. If it were a lighter color, it’d be like your home was wearing a giant white shirt all the time.

This is the idea behind the “cool roof.” Last month, Atlanta joined a growing number of American cities requiring that new roofs be more reflective. That significantly reduces temperatures not just in a building, but in the surrounding urban environment. “I really wanted to be able to approach climate change in the city of Atlanta with a diversity of tactics,” said City Council member Liliana Bakhtiari, who authored the bill, “because it’s far easier to change a local climate than it is a global one.”

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[–] 7 points 1 year ago (2 children)

sorry, I meant why aren't we using white paint. There's no way white paint is expensive compared to black paint.

The infrared cooling paint has other issues, like it doesn't withstand damage easily and the surface texture needs to be maintained very well. But like, white paint is the cheapest kind of paint, just due to commonality.

Alternatively, why aren't we growing plants on all the roofs, that would absorb even more heat without requiring air conditioning, and it would improve air quality, it could be used for farming, etc. Now that one I can understand being more expensive, but you might be able to offset it with sales of whatever you're growing up there, but that's really unlikely. So white paint really seems like a no-brainer.

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  • [–] 6 points 1 year ago* (last edited 1 year ago) (1 child)

    Editing to add this link from another comment because I had no idea that (of course) there's organized opposition by entrenched interests to prevent anything for the public good https://www.motherjones.com/politics/2025/06/dark-roof-lobby-white-reflective-roofs-laws-lobbying-urban-heat-islands/

    I don't think the current roofs are painted black - they're naturally black because roofing tar and asphalt shingles are black by default (a lot of sheet metal roofing is too but you can at least get that in most colors). So it's not a matter of swapping out paint but adding something new. It also adds a new maintenance cost - keeping the white roof clean/maintained. Paint flakes off, tarps etc wear and become tattered, dirt and pollen collect on the surface. None of this is a dealbreaker by any means but our society seems to run on defaults and there's a lot of inertia in construction and a lot of pressure on builders to keep materials costs down (even if doing so costs the owners or occupants more in the long run).

    I hope this continues to take off because it really is a big improvement.

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