One of the many modern conveniences that people in general appreciate is air conditioning. I live in the South and I appreciate central air conditioning immensely especially during the summer months but the air conditioning we are familiar with is a fairly recent invention even if the idea of artificially cooling a structure is not. In fact, affluent Romans circulated aqueduct water through the walls of their homes to cool them and there were rotary fan devices used in the Chinese Han, Tang, and Song Dynasties from the 2nd century to about 1279. These fans were operated by hand initially and transitioned to water powered systems that were fairly widespread.Medieval era societies used some ingenious devices to provide cooling. The Persians used large open pools of water called cisterns to collect rainwater. They used a system of windows and vanes to move wind across the evaporating water to cool their buildings. In Egypt, ventilators were developed that were common in homes and helped move warm air out of the houses. British scientist Michael Faraday in 1820 demonstrated that compressing liquefied ammonia and evaporating it could cool the air. Then John Gorrie, a Florida doctor, used the compressor technology to make ice in 1842 and he used it to regulate the temperature at his hospital in Apalachicola, Florida. He was unable to further develop his invention because of his main financier’s untimely demise and after his death in 1855 the whole concept of air conditioning faded for a few years.
The first modern electrical air condition system was designed in 1902 by Willis Haviland Carrier in Syracuse, NY. It was originally invented to control the temperature and humidity in a printing plant to help keep the paper from changing dimensions and throwing off the ink alignment. This technology was soon developed to meet workplace demand and was adapted to provide comfort for homes and automobiles so The Carrier Air Conditioning Company of America was born. The residential application of his technology boomed in the 1950s.The first air conditioning units used toxic or flammable chemicals such as ammonia, propane and methyl chloride which were dangerous if they leaked. Freon was developed by Thomas Midgley Jr. in 1928 and was a much safer chemical. However it was later found to harm the atmosphere and deplete ozone.
Freon is trademarked by Du Pont and several blends have been developed using a number system such as R-12, R-22, and R134A and these are being fazed out of use. Some more environmentally sound alternatives have been developed by companies like Honeywell and are being offered commercially. Air conditioning technology continues to advance and become more energy efficient but I for one am extremely glad that it makes our modern existence so comfortable.
One of the many modern conveniences that people in general appreciate is air conditioning. I live in the South and I appreciate central air conditioning immensely especially during the summer months but the air conditioning we are familiar with is a fairly recent invention even if the idea of artificially cooling a structure is not. In fact, affluent Romans circulated aqueduct water through the walls of their homes to cool them and there were rotary fan devices used in the Chinese Han, Tang, and Song Dynasties from the 2nd century to about 1279. These fans were operated by hand initially and transitioned to water powered systems that were fairly widespread.Medieval era societies used some ingenious devices to provide cooling. The Persians used large open pools of water called cisterns to collect rainwater. They used a system of windows and vanes to move wind across the evaporating water to cool their buildings. In Egypt, ventilators were developed that were common in homes and helped move warm air out of the houses. British scientist Michael Faraday in 1820 demonstrated that compressing liquefied ammonia and evaporating it could cool the air. Then John Gorrie, a Florida doctor, used the compressor technology to make ice in 1842 and he used it to regulate the temperature at his hospital in Apalachicola, Florida. He was unable to further develop his invention because of his main financier’s untimely demise and after his death in 1855 the whole concept of air conditioning faded for a few years. 
The first modern electrical air condition system was designed in 1902 by Willis Haviland Carrier in Syracuse, NY. It was originally invented to control the temperature and humidity in a printing plant to help keep the paper from changing dimensions and throwing off the ink alignment. This technology was soon developed to meet workplace demand and was adapted to provide comfort for homes and automobiles so The Carrier Air Conditioning Company of America was born. The residential application of his technology boomed in the 1950s.The first air conditioning units used toxic or flammable chemicals such as ammonia, propane and methyl chloride which were dangerous if they leaked. Freon was developed by Thomas Midgley Jr. in 1928 and was a much safer chemical. However it was later found to harm the atmosphere and deplete ozone. 
Freon is trademarked by 
