Colorful films could help buildings, cars keep their cool

The cold blast of an air conditioner can be a relief as temperatures soar, but 'A/C' units require large amounts of energy and can leak greenhouse gases. Today, scientists report an eco-friendly alternative -- a plant-based film that cools when exposed to sunlight and comes in many textures and bright, iridescent colors. The material could someday keep buildings, cars and other structures cool without requiring power.