The first fan-powered ventilation system came about in approximately 180 A.D., when inventor Ding Huan developed a manual-powered fan that drew air from a pool of cool water and distributed it through a home. The idea evolved during the Tang and Song Dynasties, when the fans were powered first by people and then by the water used to produce the cool air. One design created during the Tang dynasty employed fountains to shoot water upward and push gears, which turned the fan.
Early air-cooling designs used water as a cooling agent. The evaporated water led to increased humidity levels within the enclosed space. British scientist Michael Faraday developed a compressor in 1820 that used ammonia as an active ingredient. Faraday's greatest problem was exhausting the ammonia fumes, which could be toxic. While the coolant was not particularly safe, the compressor technology is a component that is still used today. More than 20 years later, a Florida doctor named John Gorrie used compression to make ice, which could then be used to cool structures (including his Apalachicola, Florida hospital). Gorrie's design earned a patent in 1851, although his plans died along with him 4 years later.
The first commercial air-conditioning unit was built by Willis Haviland Carrier in 1902 for the Sackett-Wilhelms Lithographing and Publishing Company in New York. The system was intended to be used to actively cool machinery used in the printing process, but Carrier discovered that not only could his design cool the air, but regulate humidity as well. Reduced humidity and temperature helped printing presses calibrate ink and paper alignment.
This development paved the way for industrial and commercial use of air conditioning. Carrier, a Cornell University-educated scientist, opened a factory in Syracuse, New York to manufacture his air-conditioning units. The Carrier Air Conditioning Company was the world's leading air-conditioning manufacturer for much of the 20th century.
The Carrier design was based on Faraday's ammonia-cooled system. The unit chilled coils with compressed ammonia, and fans would distribute the cool air throughout the premises. In 1922, Carrier introduced the chemical dielene to his construction. Dielene was a nontoxic coolant that could be used without the worry of poisoning anyone. The invention took off with movie-house operators, who used it as a gimmick to bring customers in during summer months, when business tended to wane. The first movie theater to use air conditioning was Broadway's Rivoli. The result was an explosion in demand among the owners of office buildings, stores and government buildings.
Window air conditioners in homes grew in popularity during the 1940s and 1950s. More than 1 million units were sold in 1953 alone. By the 1970s, central air-conditioning units had been developed. These pieces, smaller in size than an industrial unit, incorporated a condenser, coils and fan to draw in natural air, pass it over coils and into the dwelling's ventilation system. By the 1970s, units used DuPont-manufactured Freon as the cooling agent. While effective and economical, Freon was proven to be an ozone-depleting chemical with devastating environmental effects. The result was discontinued use of the chemical. During the late 1980s and early 1990s, Honeywell and Carrier brands developed ozone-friendly coolants to replace Freon.