Designer Joe Doucet has developed a smart exterior paint that changes color with temperature to help buildings manage energy use.The thermochromic paint turns lighter in heat and darker in the cold, reducing energy needs by up to 25%.In summer, the white paint reflects heat, keeping interiors up to 12ºF cooler, while in winter, darker tones absorb heat, warming interiors.The paint can be tinted and has potential applications in schools, factories, and other large structures.