Full story: https://www.purdue.edu/newsroom/releases/2020/Q4/this-white-paint-could-reduce-the-need-for-air-conditioning-by-keeping-surfaces-cooler-than-surroundings.html
What if paint could cool off a building enough to not need air conditioning? Prof. Xiulin Ruan has pioneered radiative cooling paint; instead of absorbing sunlight, it radiates the heat back into space. This actually cools surfaces below ambient temperature, something paint has never done before.
Mechanical Engineering: https://purdue.edu/ME