Keeping buildings cool by sending heat into outer space

With about 15% of the world's electricity used for cooling, making air-conditioning systems more efficient could go a long way to ease future energy demand. A group of scientists in sunny California reckons it can do just that via "radiative cooling" – a process requiring essentially no external source of power that transmits unwanted heat into the cold of outer space via infrared emission. The researchers have shown that a device able to reflect almost all incoming radiation from the Sun while simultaneously emitting in the infrared could reduce electricity consumption from air conditioners by at least a fifth.