(Roughly) Daily

A new twist on an old-school climate adaptation technique– Lara Williams reports…

In a co-working space overlooking the west London neighborhood of White City, a host of startups are at work on flashy technologies ranging from a breath test that can detect multiple cancers to a pain-free tattoo. Surrounded by that kind of innovation, a visitor might overlook the lab stocked with little more than tubs of white powder and paint pots. After all, how interesting can white paint be?

When it comes to adapting to a hotter planet, the answer is: very.

As record temperatures baked Europe this summer, people desperately sought ways to cool their homes and workplaces. I stuck emergency foil blankets to my windows in an attempt to stop the heat from getting in; others tried coating the glass in yogurt or chalk. But of course, the most popular and effective option was air conditioning.

Sales of both conventional and portable units shot up this year, and the need for that cool breeze is only going in one direction: By 2035, the International Energy Agency predicts that global cooling demand could grow by about 2,300 terawatt-hours. (For context, that’s more than India’s total electricity demand in 2025.)

This is bad news for the energy transition. Consider that in 2023, the UK fired up a coal plant during a heatwave to meet AC demand. Yes, air conditioning can be a literal lifesaver, but if we want to avoid making the planet even hotter, it can’t be our only strategy.

That’s where paint comes in.

People in countries like Greece and Spain have been painting their homes white to keep them cool for centuries. White reflects most sunlight, making it better than other colors at preventing solar energy from being absorbed as heat. Commercial “solar-reflecting” paints reflect up to 90% of sunlight, but recent innovations in materials science promise to make white paint’s cooling properties even stronger.

The secret is something called daytime radiative cooling. Any object with a temperature above absolute zero emits heat as thermal infrared radiation. Some infrared wavelengths transfer more heat because they are able to pass through the atmosphere into the freezing depths of space. That process is how our planet cools itself.

Typically, net cooling only happens at night, when there’s no incoming sunlight — and therefore solar radiation — adding more heat. But in 2014, researchers at Stanford University demonstrated that it was possible to chill a surface to 5C below the ambient air temperature during the day by combining the power of reflective cooling (i.e. when white paint reflects sunlight) and radiative cooling (what happens when infrared radiation passes through the atmosphere).

More than a decade later, this technology is making its way into the marketplace…

[Williams describes the entrepreneurial efforts underway, examines their challenges, and explores their potential. She concludes…]

… Innovations that improve our lives don’t always look like talking computers or flying cars. As someone who suffered through too many sweaty, sleepless nights this summer, that humble bucket of white paint is starting to look pretty exciting.

“Why I’m Excited About a Bucket of White Paint” (gift link, or archived link), from @lararhiannon.bsky.social in @opinion.bloomberg.com.

* Jeremiah Brent

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As we stay cool, we might spare a thought for Sir John Leslie; he died on this date in 1832. A Scottish mathematician and physicist, he best remembered for his research into heat. Leslie gave the first modern account of capillary action in 1802 and froze water using an air-pump in 1810, the first artificial production of ice. Then, in 1804, he helped lay the scientific groundwork for the advances considered in the article linked above: he experimented with radiant heat using a cubical vessel filled with boiling water. One side of the cube was composed of highly polished metal, two of dull metal (copper), and one side painted black. He showed that radiation was greatest from the black side and negligible from the polished side. The apparatus is known as a Leslie cube.

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