2 billion

The two billion air conditioning units in the world consume about nine per cent of global electricity production, and emit a billion tons of carbon dioxide. As A/C demand is set to grow two thirds over the next decade, mostly from developing nations, researchers looked for a healthier cooling method. In temperatures above 30C with more than 66 per cent relative humidity and barely a breeze, study participants stood or sat in a “cold tube” pavilion — with panels containing insulated capillaries full of chilled water enclosed in a polyethylene membrane — and felt cool, said Adam Rysanek of the University of British Columbia. This “radiant cooling” method could cut hydrofluorocarbon use, and thus avoid an additional 1C of warming.