re: Scientists created the world's whitest paint could eliminate the need for A/C

Of course it’s white paint. Would expect nothing less from racist science

Unless it’s climate science. That is set in stone and unimpeachable

Wouldn’t this just reflect more heat back into the the atmosphere and increase “global warming”? Same problem caused by concrete heat islands in cities.

How is it going to work when the entire roof is covered with solar panels?

And when all the roofs are painted white and that radiation gets reflected back into the sky, then what???

That’s racist…

Wishful thinking. Could help cool but not eliminate need for A/C

10kw = 34,122 BTU/hr

Not quite a 3 ton unit (12,000 btu per ton)

Also you need to cool air to dew point in order to remove moisture. Any humid climate will need an A/C system just for de-humidification. Especially a system to requires outside air.

Next, once the pint gets dirty it will quickly lose its reflective power.

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or even eliminate the need for air conditioning, scientists say

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bullshite.

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Using this new paint to cover a roof area of about 1,000 square feet could result in a cooling power of 10 kilowatts. “That’s more powerful than the air conditioners used by most houses,” Ruan said.

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bullshite.

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The paint reflects 98.1% of solar radiation while also emitting infrared heat

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What are the unintended consequences of this?

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Barium sulphate

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from the guiness link:

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Seeking to highlight the potential benefits of radiative cooling, Professor Xiulin Ruan (who was part of the study) said: “If you were to use this paint to cover a roof area of about 1,000 square feet [93 m2], we estimate that you could get a cooling power up to 10 kilowatts. That’s more powerful than the air conditioners used by most houses.” Scaling that up, the scientists estimate that it would only require 0.5–1% of Earth’s surface to be coated in this paint (e.g., by painting roofs) to reverse global warming to date.

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Oil-based paint (oh, the irony). From the ACS website:

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The BaSO4-acrylic paint is developed with a 60% volume concentration to enhance the reliability in outdoor applications, achieving a solar reflectance of 98.1% and a sky window emissivity of 0.95.

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Where does the heat go when it is reflected? I know it doesn't go back to the sun. Does it stay in the atmosphere?

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neither of those claims to actively make an area cooler than surrounding temperatures like the paint in the article does

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It’s an interesting claim. At first I was going to say that I think it would probably be more accurate to state that a surface coated with the paint “heats up less than the surrounding area” when exposed to sunlight. Using the term “cooled” seems a bit misleading because it implies active removal of heat from the surface.

But then I re-read this piece:

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The paint reflects 98.1% of solar radiation while also emitting infrared heat. Because the paint absorbs less heat from the sun than it emits, a surface coated with this paint is cooled below the surrounding temperature without consuming power.

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So basically they are saying that the infrared emissions from the coating more than offset the 1.9% of solar radiation that still gets absorbed. If that is indeed the case, then the end result would be active cooling of the surface.

That being said, I’m skeptical that this can lead to active cooling inside a building. As the surface cools, it’s going to develop a temperature gradient with its surroundings and consequently absorb more heat via convention and conduction. The question becomes how much heat actually gets absorbed from the inside of the building. The air on top of the painted surface is going to be much hotter because A) it’s (presumably) hot outside and B) the air is being heated by sunlight from both directions - the direct heat from the sun and the reflected heat from the paint. It seems to me like most of that cooling would be wasted on the ambient air.

So it’s not good enough to just paint the roof. You would also need to design the building to both minimize convective heat transfer from the roof to the atmosphere and also maximize heat transfer from the interior to the roof. In hot climates, this would be the exact opposite of traditional designs.

ETA: All of that said, it would almost certainly result in an overall energy efficiency improvement, just by absorbing less overall heat from the surroundings than the alternative.