1902

Air Conditioning

Willis Carrier (1876–1950)

Some of the technologies that engineers create are essential for making life bearable in certain parts of the world. Air conditioning is a great example of this.

Invented by American engineer Willis Carrier in 1902, the idea for air conditioning is surprisingly simple. Take a liquid that boils at something like -20°F (-29°C). Squirt it at low pressure into a pipe. Inside that pipe the liquid will boil, leaving the pipe at -20°F. Then, take a pump to suck out the vapor. Compress the vapor at high pressure and stuff it into another pipe. That pipe will be hot with the heat of compression. As the vapor cools, it condenses back to a liquid. The liquid squirts back into the cold pipe and the cycle repeats. Put the cold pipe in the building with a fan, and the hot pipe outside with another fan, and voila—air conditioning.

Once this simple cycle was invented, engineers went to work making efficient, inexpensive motors and compressors, and creating systems in all different sizes. Today you can buy a small room air conditioner for $100. It is also possible to buy a complete building-wide air conditioning system big enough to cool off an entire stadium or a sprawling airport. Cars, planes, and boats have air conditioners, too.

Once perfected in buildings, air conditioning technology morphed to create the refrigerator/freezer. The box that makes up the refrigerator is essentially a very small, well-insulated room.

Several things that we take for granted today would not be possible without air conditioning and refrigeration: frozen foods and the modern server farm come to mind.

With the development of inexpensive, reliable air conditioning systems, areas around the globe that had been inhibited by extremely hot weather became bearable, and they grew rapidly. One key technology changed the entire economic landscape in these areas.

SEE ALSO Electric Refrigeration (1927), Frozen Pizza (1957), Irradiated Food (1963), Toy Story Animated Movie (1995).

This rooftop air conditioning system is located in Hong Kong.