In lists of history’s most significant inventions air conditioning is regularly cited: a technology that lets us live and work in some of the most inhospitable places on the planet. But what if we had missed a rather simpler solution: paint. Researchers have designed a paint that reflects 96 per cent of the sun’s heat, meaning it leaves a building’s walls 6C cooler than the surrounding air. They said that the paint, which they described in the journal Science, could greatly reduce the need for air conditioning. In hot countries cooling buildings accounts for a significant proportion of electricity consumption – 17 per cent in the US alone. This means that it is a significant contributor to global warming. Although in several Mediterranean countries there is a tradition of painting buildings white, conventional white paint reflects about 80 per cent of visible light, and is bad at reflecting that in the ultraviolet and near-infrared parts of the spectrum. The new paint was made after physicists at Columbia University in New York noticed an unusual effect in a polymer. When this polymer turned from liquid to a thin solid film, they found that under certain conditions it went from colourless to white. It had formed a spongey consistency, from which the whiteness was derived – in the same way that colourless water turns white when it forms snow.
Times 28th Sept 2018 read more »