WW2-era Radiative Cooling

Last year, I started a thread in the ASB forum about the potential to build passive radiative coolers in the 19th century:
https://www.alternatehistory.com/forum/threads/wi-earlier-air-conditioning.447607/
The thread has a handy link to a TED talk on the technology.

Well, it seems researchers at SUNY Buffalo have make a breakthrough in this technology:
https://apple.news/AnR0taZPMRgmD7Bsr_1XFag
This version does no require anything so exotic as hafnium dioxide. It uses plain old aluminum and PDMS - thats the key ingredient in silly putty, originally invented in 1943.

So, lets assume that, besides finding that this attempt at a rubber substitute is a lot of fun to play with, researchers stumble onto this particular use - if you want a fun anecdote, some gets spilled onto aluminum foil by a window on a hot day, and someone notices that it is super reflective. Whatever. Its 1943ish, and the US military has the technology to build air conditioners that don’t need electricity - just line of sight toward the sky.

The first use would be in the island hopping campaigns, as a low-cost way to keep quonset huts cool (assuming it gets put into production quickly enough). After the war, these units would likely get commercialized. They would certainly be popular in the US sunbelt, but I think an even better niche would be the developing world, as the big appeal to these units is that they don’t need electricity.

This means that loads of very poor populations that can’t afford reliable power can afford effective air conditioning.

So, how might the development of these countries differ with this opportunity?
 
Reading the article I have to say that this smells a lot like the EM drive and the various water finders/purifiers that keep popping up. The effectiveness of radiative cooling is proportional to the surface area and temperature of the radiating surface (the hotter the better). The square cube law being what it is, I am deeply skeptical that the math will work out at human comfortable temperatures for a building of meaningful size, especially if the plan to rely on passive circulation.

They say thier system lowers the measured temp of the enclosed space by 6 degc in direct sunlight which isn't unbelivable, but I find myself wondering how that temperature compares one measured in the shade or covering the same box with a space-blanket.
 
Reading the article I have to say that this smells a lot like the EM drive and the various water finders/purifiers that keep popping up. The effectiveness of radiative cooling is proportional to the surface area and temperature of the radiating surface (the hotter the better). The square cube law being what it is, I am deeply skeptical that the math will work out at human comfortable temperatures for a building of meaningful size, especially if the plan to rely on passive circulation.

They say thier system lowers the measured temp of the enclosed space by 6 degc in direct sunlight which isn't unbelivable, but I find myself wondering how that temperature compares one measured in the shade or covering the same box with a space-blanket.

Its a fairly well-attested technology, just one in its infancy. There’s nothing magical about it. Hell, the fundamental concept has been used for millennia, just only at night.
 
To the original question: if the US, the USSR or the Nazis were able to produce working surface coolers in WWII, my guess is that the effects would be minimal. All armies relied on the draft rather then on recruiting career soldiers. So you really didn't have much incentive to keep your soldiers comfortable. You just had to keep them functioning. In all the question would be: if the army could somehow produce an Air condition unit at 1/10 of the regular post, how much more barracks would end up equiped with it? The answer is probably: not very much.
 
For a Quonset hit maybe. But what about humidity? Any water in the air will condense inside the building. The buildings also have to have direct sunlight. Can’t put them in the shade. What about dust and bird poop and airborne crap in general? Will you have to clean the roof constantly? How long will the roof last? Will dust clog the pores of the putty and drop the efficiency? What about air movement inside the structure? Will the temperature difference on the inside surface of the ceiling be enough to cause natural circulation? Seems that multiple rooms could be a problem with airflow. A central air unit balances the flow in and out of the structure and between rooms. Don’t see how you could refresh the air. Modern systems have heat exchangers that precool the outside air as it comes in with air leaving. Would get stale pretty quick with no air exchange.

A central air conditioner is a system. It cools (and heats some if a heat pump), moves, refreshes and filters the air and removes water from the air to drain outside. But the best thing for average Joe citizen is that it works. 24/7, no cleaning the roof and just minimal maintenance.

IMHO It’s an interesting technology but just don’t see it being used that much.
 
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