Passively Cooling below Ambient Temperature by Radiating Infrared into the Sky

The humble apostrophe trips up the title card with the innovative orthography of “ain’t”.


I call BS on the economics.

His predicted worldwide savings likely don’t pay for outfitting a medium size city.

Applicability is narrow. This is not going to be relevant to a highrise apartment building.

Even in rural situations, how does it compare to alternatives like ground source heat pumps in cooling mode? And those also offer benefits in heating.

BTW, The 1980s called and they want their jacket back.


Also, as he points out near the end of the video, the performance of the scheme depends strongly on being able to radiate the heat into a clear sky, ideally with low relative humidity. If there are clouds, fog, precipitation, or just high humidity, water, which strongly absorbs in the infrared, will dramatically raise the effective temperature of the sky and reduce the ability to reject heat to space.

The trick of making ice cream in a desert by placing the cream in a hole in the ground insulated with straw or other material so it is exposed to space at night works only due to the atmosphere having close to zero relative humidity. (The hole in the ground blocks convection of air which would bring in heat from the surroundings.)


There are so many things wrong with this that it’s hard to know where to begin. The apostrophe catastrophe should have been a clue. More substantively, this doesn’t work on cloudy days since low clouds aren’t that cold. Maybe he considers this; I couldn’t sit through the whole video. He’s also wrong about human basal metabolic rate by about a factor of two: an unforgivable error in the era of the internet.


As I often remind fanatics of greenhouse gases: I don’t live in a greenhouse(!)

Deep space is COLD….


The biggest savings would come from not cooling/heating whole living spaces, but instead just our bodies. Frank Herbert nicely conveyed this vision here:


This is a great science fair idea… waiting to figure out the supercoating ingredients. He said in this video that he will walk the viewers through how to make the paint, but I didn’t catch that.

Not sure the temperature differential can play out commercially, but it’s a neat gadget. As CTLaw noted, ground source heat pumps will probably work better.