Buildings coated in a cement-based paint that “sweats” could help keep communities cool during the hottest days of the year. Keeping cool when temperatures rise is one of a building’s largest costs. On top of this, passive cooling is generally directional, meaning that it’s less effective on vertical surfaces and those lacking a direct angling towards the sky. The construction material can absorb an immense amount of liquid, while sweating is the body’s primary method to leverage evaporation’s passive cooling effects. They then slathered a small model home in their paint and compared its cooling ability to another pair of houses: one coated in standard exterior paint, and another in a commercially available paint that relies on radiative cooling.