Air-conditioning is one of the world’s great overlooked industries. Automobiles and air-conditioners were invented at roughly the same time, and both have had a huge impact on where people live and work. Unlike cars, though, air-conditioners have drawn little criticism for their social impact, emissions or energy efficiency. And whereas cars are quickly becoming more efficient, air-conditioners are not. Here’s what can be done about the world’s air-conditioning problem, according to The Economist.