The sun supports all life on earth yet in some cases it can have damaging effects. Sunlight can heat up the colorful surfaces of buildings, which can raise their internal temperature and place heavy loads on air-conditioning systems, increasing energy usage and related CO2 emissions. Heat from the sun can also cause colorful exterior polymer systems to degrade and warp, which can reduce product lifetimes, increase waste, and increase cost for consumers. There is a global initiative1 underway that challenges us to reduce the energy usage of buildings, and cool roofs can help achieve energy reduction targets.