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, <a href="https://en.wikipedia.org/wiki/Infrared_window" rel="nofollow">https://en.wikipedia.org/wiki/Infrared_window</a>) 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. <a href="https://www.skycoolsystems.com/technology/" rel="nofollow">https://www.skycoolsystems.com/technology/</a>