Tricky wording. Right now it is 15 degrees warmer outside than inside my house, No AC yet. Thermal mass. Insulation. No magic way around the rule of thermodynamics. It's about time to turn the AC on, though.
The claim that you can radiate heat from cooler to warmer ... that's perpetual motion machine stuff. LOL. What's sad is when anyone believes any of it. These magic paints come out every few years. PT Barnum. Politics. People want to believe.
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This is a real product category, just not these guys or their claims.
Cool Paints
Strictly speaking, the paint doesn’t have to violate thermodynamics to work...but it would have to overcome extremely unfavorable statistics.
In principle, any pigment capable of two-photon absorption could luminesce at a higher frequency. We’ve observed this using high-powered lasers as the light source. In fact, it was purely theoretical until high-flux lasers became available. Under ambient photon flux, however, excited-state lifetimes are too short and photon density too low for a realistic statistical hope for a second photon to arrive while the molecule is still excited.
The statistics are somewhat more favorable for phosphorescence. I’ve spent some time wondering whether it might be possible to design a phosphorescent molecule with a sufficiently long-lived excited state to enable two-photon absorption of ambient IR radiation. In principle, this could allow excitation from the triplet state to an even higher electronic state, which could then relax by emitting a higher-energy photon...effectively converting absorbed IR into visible or UV light. At the time I was wondering if a pigment could be engineered to absorb IR and act as a kind of “night-light” paint (e.g., for a bathroom). I was not thinking about the pigment as a cooling agent. I was only thinking about IR radiation because (presumably) if you need a nightlight, the lights would be off in the bathroom and IR radiation is all you could count on. I even sketched out the a possible Jablonski diagram.
If one could create a long-lived triplet state capable of absorbing a second IR photon, then such a mechanism could, in principle, achieve what this “paint” claims to do.
Something similar (but in reverse) has already been developed. Early in my career, I was an intern in a lab developing DayGlo pigments (the super bright yellow and orange you see on highway worker vests and even in bingo markers).
The dayglo pigments work by pairing a fluorescent dye with a conventional pigment of similar color. The fluorescent component absorbs UV light and re-emits it as visible light near the frequency of the conventional pigment, while the regular pigment reflects that light as usual. The result is that more light of a particular color is leaving the surface of the paint than what struck the paint. This is why those pigments seem so bright.
cryox.co
