interestingasfuck

Huh, tldr might be a bit hard but I'll summarize-ish.

Everything radiates heat, you do, the air, the floor does, etc, you can see w/ infrared camera. Most of that energy is radiated in a wide frequency band (it's all over the place), absorbed by your surroundings and re-radiated and energy just kinda bounces around. If you paint your roof white, you don't absorb extra heat from the color and can reflect light into the air, but then the air gets hotter so it helps a bit we all know white reflects and black absorbs.

Well, there's a small band of electromagnetic frequencies that the atmosphere is virtually transparent to. In the last decade or so scientist have invented special metamaterials, which instead of radiating their heat in a wide band, radiates most of it in a narrow band, the band that can pass through the atmosphere. This means that it beams infrared energy out into space at a far higher level than anything else.

Because the heat is radiated into space passing through the atmosphere, these materials can actually cool themselves significantly below ambient temperature. Utilized properly, this cooling can be used to cool buildings and many other things without consuming energy at all.

This particular video, this guy is able to accomplish this without exotic or dangerous materials so you can DIY (since these materials are not even for sale yet).