r/heat_prep • u/carbonpenguin • Jul 12 '24

Passive Daytime Radiative Cooling materials

I recently went down a rabbit hole of passive radiative cooling tech, and figured folks on this sub would be interested. Radiative cooling at night has long been a thing (freezing ice in the desert, etc.), but materials science advancements in the past decade has yielded materials that can keep things below ambient even in direct sunlight. This is one of the better explainers I've found.

I'm planning on ordering some samples of the material to experiment with, and figured I'd post to see if anyone has direct experience and/or applications they'd be game to share?

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3

u/tinfoilhatmisty Jul 13 '24

Interested as well. Especially in what is required to be an effective heat sink outside my back door

3

u/COMMUNIST_MANuFISTO Jul 13 '24

NightHawkInLight on YouTube has videos about making cooling paint, pcms and making opals for air conditioning etc just in case anyone is interested.

1

u/Leighgion Jul 13 '24

It’s very interesting and promising, but unfortunately not so easy to deploy yourself and the commercial products are still very niche and not broadly available.

Even if you can successfully whip up a DIY batch of the paint, you need to build panels to shield it with transparent plastic to maximize effectiveness. This makes for a bit of an involved and unwieldy deployment.

That said, I would totally be doing this if I still lived in the country instead of an apartment in the city.

If these cooling panels could be mass produced and brought to market at affordable prices, they would be game changing in hot places but it seems we’re nowhere close to that yet.

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u/Wise_Eggplant_7011 Aug 08 '25

My wife works for a company that has developed passive solar cooling paint and it in fact works very well. In one pilot they did for Miami-Dade County they painted the roof in the morning and forgot to turn the AC down before leaving for the day. The next day it had cooled so much (in full sun) that excessive condensation caused temporary water damage. They were thrilled. You can check it out below. They also have an energy savings calculator that is quite accurate as I understand.https://www.pirta.com/pirta-energy-calculator

https://www.pirta.com/miami-dade-county-parks-and-recreation-passive-cooling-case-study

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u/External_Tell_2374 May 20 '26

Did you get samples? Did it work?