Typical commercial white paints reject 80%-90% of visible light, but still absorbs ultraviolet light. So it still warms up. Researchers have developed an ultra-white paint which can reject 98% of sunlight, including ultraviolet light. It also releases infrared light, which effectively means the paint can cool itself below surrounding temperatures. The inventors hope it can provide a low-cost, scalable replacement to air conditioning. https://www.purdue.edu/newsroom/releases/2021/Q2/the-whitest-paint-is-here-and-its-the-coolest.-literally..html