The Whitest Paint Ever Could Cool Cities and Fight Climate Change

Jun 4

Written By Michele Edington (formerly Michele Gargiulo)

In a small lab at Purdue University, a team of engineers painted a strip of brilliance onto our climate future. Don’t get me wrong, if you’ve been here before you know I’m all for the environment in a lot of ways. Some of those ways I’ve been very vocal about (I think that most of the government trying to “fix” climate change is a scam where they’re stealing the money), while others I think are more subtle and probably go right over my head most of the time. This invention though, is nothing short of brilliant.

It was just white paint. So white, in fact, it might just change the temperature of the world.

This isn’t white power nonsense or me being a crusader or anything, it’s just me marveling at the actual color (don’t care what color your skin is, you’re beautiful). This is engineered white…the most reflective substance ever put in a paint can. It deflects 98.1% of sunlight and cools surfaces below ambient temperatures. It could very well become one of the simplest, cheapest, most powerful tools in our climate arsenal.

And all you have to do is brush it on.

The Reflective Power of White

I’d be remiss if I skip over my lesson from the sun. Sunlight travels 93 million miles to reach us, and Earth absorbs much of that energy. Earth is a greedy little thing, and we should all be grateful for it in that way. Plants certainly are. Dark roofs, asphalt roads, and tar-coated warehouses drink it in like thirsty stone, holding the heat long after sunset. White surfaces (true white) do something else entirely though, they send the light back.

Reflectivity is a defense that we haven’t used enough. It’s how light-colored desert animals survive heat, and it’s why you wear white on scorching days. Most white paint doesn’t do enough though. Commercial white coatings reflect about 80–90% of solar radiation, the rest gets absorbed, warming the material beneath.

Purdue’s paint reflects 98.1% of sunlight…and it does something no other paint can. It emits infrared heat through a process called radiative cooling, effectively pushing heat into deep space! Under direct sun, it can cool surfaces up to 8°F (4.5°C) below ambient air temperatures…without using a single watt of electricity.

That’s a legitimate climate strategy, not the nonsense that the world is saying we need to do that actually makes little to no difference at all. I also think it’s absolutely incredible that most of the carbon emissions in the world are caused by companies, but our world leaders like to shame us for our tiny little part in it.

The secret ingredient in this paint is barium sulfate, a compound already found in photo paper, makeup, and medical imaging. Paint is more than ingredients though, it’s particle physics in a can. What Ruan’s team did differently was alter the particle size distribution of the barium sulfate. Instead of uniform particles, they used a variety of sizes, each scattering a different wavelength of sunlight. This creates near-total reflectance across the full solar spectrum…from UV through visible to near-infrared.

Most paints absorb enough heat that they eventually warm up, but this one doesn’t. Its emissivity (its ability to radiate energy) actually allows it to cool even in direct sunlight. It’s like painting your roof with a sheet of ice that never melts.

This paint on a city could change the game.

Urban areas trap heat in what scientists call the urban heat island effect. Skyscrapers, concrete plazas, and dark rooftops soak up radiation all day, turning cities into low-simmer furnaces. This heat raises air conditioning demands, strains electrical grids, and worsens pollution…especially in poor neighborhoods without adequate cooling.

In cities like Phoenix, Delhi, Cairo, and even New York, pavement and buildings can drive temperatures up to 7°F (4°C) hotter than nearby rural areas. That’s not just uncomfortable, in some areas it’s actually deadly. During heatwaves, these islands of urban heat become pressure cookers for vulnerable populations. Now coat those buildings with this paint and suddenly, the roof isn’t absorbing heat…it’s rejecting it. Office buildings would stay cooler, as apartment complexes reduce A/C usage. Asphalt doesn’t radiate warmth back into the sky and air conditioners don’t have to work overtime would mean that the grid breathes easier.

Multiply that across a city block, a borough, or an entire metro area and you’re lowering regional temperature with nothing more than paint. Of course the climate activists don’t want you to use this. If you stop giving them money to fix climate change then there’s less money for them to steal and buy themselves nice cars and homes with.

Radiative Cooling

It sounds futuristic, but it’s truly rooted in ancient thermodynamics. Radiative cooling refers to the ability of a surface to emit heat as infrared radiation, allowing it to lose energy to the sky, even under sunlight. It’s how deserts cool rapidly at night and how the human body stays cool through sweat evaporation and radiation.

This paint leverages that same principle…but better.

By emitting mid-infrared radiation into the 8–13 micron wavelength range (what scientists call the “atmospheric window”) the paint can release heat directly into space, bypassing the warming layers of Earth’s atmosphere. This makes it a passive cooling system with no power needed, just paint, doing the work of an air conditioner, while reducing the need for one.

Unlike other geoengineering proposals that require mirrors in orbit or giant sulfur injections into the stratosphere, this one isn’t theoretical. It exists…in a can, right now.

We’ve seen a surge in climate innovation: solar panels that track the sun, carbon capture machines, lab-grown meat, algae biofuels, and electric everything. I’m not saying these aren’t important, all of them are vital for us to truly work on this issue, but few are this immediately applicable.

You don’t need legislation to paint a roof or a utility company, a subsidy, or a specialized installer. You need a roller and some time. That’s what makes this such a breakthrough, it democratizes adaptation. It’s affordable, scalable, and super simple…which makes it radical.

We are facing a paradox: the hotter the world gets, the more we rely on cooling systems that increase emissions. Air conditioning already accounts for 10% of global electricity use, and by 2050, that number could triple. Cooling is one of the great energy dilemmas of the 21st century. Cooling without energy is a bridge out of that paradox. A way to cool buildings, cities, and perhaps even regions without consuming more fossil fuel.

Paint enough surfaces, and you start to imagine a different world. A world where summers don’t kill, where cities don’t bake, where relief doesn’t come with a monthly electric bill.

Not All White Paints Are Equal

Of course, this isn’t a magic fix yet.

There are limitations for any new invention, and this is no exception. The current formulation might not withstand harsh conditions (like rain, snow, or abrasion) without degradation over time. Barium sulfate is also a little pricier than traditional paint ingredients. Also, the paint must be applied correctly and may require re-coating after a few years.

The researchers are already working on improvements, versions for cars, ships, even spacecraft. There's a road ahead, but it’s painted bright.

Sometimes, beginnings are all we need and a little hope can go a long way.

To read more, check out the article from Perdue.

The Whitest Paint Ever Could Cool Cities and Fight Climate Change

The Reflective Power of White

Radiative Cooling

Not All White Paints Are Equal

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