NOTE: The linked article does not include a correction from the original press release. The “40F” cooling ability should be only “about 7F”.

https://www.acs.org/pressroom/newsreleases/2023/march/colorf...

There's an interesting startup company out of Shanhui Fan's group at Stanford that is commercializing something like this -- SkyCool Systems. Their panels radiate in the 8-13µm region (the mid-infrared atmospheric window, https://en.wikipedia.org/wiki/Infrared_window) and are used to increase the efficiencies of HVAC systems. They claim efficiency gains of 10-40% as an add-on, and more if the cooling requirement can be handled solely with their panels. https://www.skycoolsystems.com/technology/

It's interesting that this requires sunlight. Here's a paint solution that doesn't and still uses passive cooling for below air temps (sun or shade): https://www.youtube.com/playlist?list=PLzrI14lOlSqeS5pNkRCiV... (the last 2 videos)