Willis Carrier designed the first modern controlled-humidity cooling system in 1902 for a Brooklyn printing plant, and in 1906 patented apparatus for treating air. Mechanical cooling spread from factories to cinemas, department stores and offices, and after the Second World War to homes. By removing the need for cross-ventilation, it freed building plans from deep-set windows and courtyards and made deep-floorplate towers and sealed glass facades habitable. It also enabled the rapid growth of hot-climate cities across the American Sun Belt and the Gulf.
Air conditioning detached building form from climate, enabling deep, sealed towers and the explosive urbanisation of hot regions that were previously hard to inhabit.
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