Modern air conditioning was invented to keep ink lined up in a Brooklyn print shop
Willis Carrier's 1902 system for a Brooklyn lithography firm was not built for human comfort. It controlled humidity so paper would stop swelling and shrinking, keeping colour inks aligned. That industrial fix became the technology that now uses about 7 percent of the world's electricity.
People were cooling buildings long before machines. The ancient city of Hamoukar in present-day Syria had double-walled living quarters with an air gap to promote airflow, and Egyptian builders used many passive techniques that later spread from Iberia across North Africa and the Middle East to northern India. Those methods fell out of fashion in the twentieth century but are now being revived using engineering studies of traditional buildings.
Artificial cold has a showman's history. Giambattista della Porta described in 1558 how mixing ice with saltpetre drives it far below freezing, and in 1620 Cornelis Drebbel staged 'Turning Summer into Winter' for James I, chilling part of Westminster's Great Hall with troughs and vats. In 1758 Benjamin Franklin and the Cambridge chemist John Hadley used bellows to evaporate ether from a thermometer bulb, dropping it to minus 14 degrees Celsius on an 18-degree day. Michael Faraday found in 1820 that evaporating liquefied ammonia chills air, and in 1842 the Florida physician John Gorrie made ice to cool his patients, dreaming of air-conditioned cities.
Electric motors made machines practical. In 1894 the Hungarian engineer István Röck began building electrically driven ammonia compressors with Ganz Works, and by 1896 his factory offered dry-air cooling units for hospitals, theatres and homes. Carrier patented his spray-type Apparatus for Treating Air on 2 January 1906 and sold one that year to Chronicle Cotton Mills in Belmont, North Carolina, since humidity affects textile fibres. It did not work well at first, but the lessons shaped his next installation in 1907.
Historians rank air conditioning alongside highways and suburbs as a force behind postwar metropolitan growth. The International Energy Agency counted 1.6 billion units in 2016, an estimated 190,000 heat deaths are averted each year, and by 2022 the technology produced 3 percent of greenhouse emissions.
Source: Air conditioning
