Keeping Cool - A Brief History of Air Conditioners

Though you might think of air conditioning as a modern invention, the concept of cooling the interior of a building actually goes back to early civilisations. In 2nd century China, the inventor Ding Huan of the Han Dynasty came up with the idea of a manually powered rotary fan, and other water powered fans were also developed in various Imperial palaces.

Medieval Persia also experimented with various cooling structures; for example, wind towers (also known as wind catchers) which were built in places like Iran to create naturally cooled ventilation using ingenious architecture to draw cool air up from a sublevel pool or stream of water, and keep the airspace inside the building much cooler than the outside. These structures have been used for centuries to cool mosques and houses. Indeed, the wind catcher is such an effective refrigeration device that they are capable of storing water at a near freezing temperature, even during the hot Iranian summer.

However, it wasn't until 1820 that British scientist and inventor Michael Faraday took air cooling a massive step forward, when he discovered that compressing and liquefying ammonia could rapidly cool air down. This discovery lead to further developments, and eventually the artificial creation of ice and crude air conditioning units; though, in these early days, these were used to cool air for industrial purposes, rather than home comfort.

In 1902, Willis Carrier invented the first modern electrical air conditioning units, which could not only control temperature, but also humidity. This was imperative for the printing plants of the time, which needed to maintain constant conditions for paper dimensions and ink alignment. A side effect of this was that it also increased productivity of the employees as they could work faster in the pleasant conditions, and thus the idea of using air conditioners in homes and cars was born.

The early air conditioners used harmful or flammable gases such as ammonia, methyl chloride and propane, which could result in injury or death if they leaked out. Subsequently, the search for a safer coolant brought the first CFC - Freon - in 1928, but this was later found to be destructive to the Ozone layer in the atmosphere, and is no longer being used. Instead the most common coolant is an HFC called R-22, which is much safer for both humans and the atmosphere; newer, more environmentally friendly versions of R-22 have also been developed for use in newer air conditioning systems, especially in the UK where environmental regulations are strict.

The growth of air-conditioning in homes and businesses across the world has allowed man to live comfortably in what would otherwise be fairly uncomfortable, if not inhospitable regions. In countries like Australia, Japan, large parts of the USA and much of South America, air conditioned buildings are the norm, and they continue to keep people cool, in an ever-warming world.