Most of us take our air conditioning for granted, knowing that we can be cool and comfortable indoors, regardless of how hot it is outside. That refreshing cool air isn’t just in your home; it’s there when you go to the office, shop in a store, eat in a restaurant or take in a movie. Of course, it hasn’t always been that way, and back at the beginning of the 20th century, there was no such thing as A/C. To keep cool, you had to head to the coast or the mountains.
What Exactly is Air Conditioning?
It’s about more than just keeping us cool, although many of us don’t quite understand how it works or what exactly it is. When you have your air conditioner running on a hot day, you are almost creating an artificial climate, one that’s colder inside than the outside. Whether it’s a building or just one room, air conditioning is able to keep the moisture content, humidity and temperature at the ideal level and if needed, add moisture to circulate that cooler air. In much the same way as a hot day causes water drops to condense on a glass of cold water, air conditioning removes water from the air by passing that air over cold pipes.
It’s relatively easy to cool the air in a dry climate. Dry, hot air being blown onto a fiber mat soaked in water, by means of a large fan will provide you with cool air as the water evaporates.
Maintaining the right temperature is important in many industries, and air conditioning has a bigger role to play than just keeping you cool at home or work. Because changing levels of moisture in the air can shrink or stretch cotton, wool, and other fibers, the right temperature is essential in making sure cloth is always high quality. Antibiotic cultures can be damaged if they are exposed to the wrong temperature, and precision instruments or machine parts can even be damaged by excess moisture in the air or on the fingertips of someone handling those parts. The US space program relies heavily on air conditioning keeping facilities and parts at the right temperature, everything from tracking missiles in the atmosphere to manufacturing them. And A/C has made it possible for men to work deep under the ground in mines, such as those in South Africa where diamonds are mined. It would simply be too hot down there without effective air conditioning.
For centuries, some form of air conditioning has been used in hot climates. Woven mats soaked in water and draped across the entrance to homes was a method of keeping cool employed in ancient Rome and Egypt; the water evaporating helped to cool the air inside the dwelling. And a primitive type of fan powered by water was devised by the famous inventor and artist Leonardo da Vinci.
High humidity means there is a lot of moisture content in the air, and it’s this high level of moisture that makes us feel uncomfortable. Many early ideas for air conditioning worked by adding more water to the air which because the water was just soaked up by the air, actually didn’t help much.
Often known as the father of air conditioning, in 1902 Willis Carrier devised a machine that cooled the air and provided low humidity. The owners of a New York based printing plant were having problems with the paper actually changing its size between different print runs, due to fluctuating moisture levels in the air. Carrier solved the dilemma by installing some cold pipes and then drawing the air over them; the excess moisture was condensed and the humidity levels remained constant. An added bonus was that the workers in the factory felt much cooler too.
During the first World War, factories that produced ammunition began to realize the importance of air conditioning. Following the war, the wonderful new invention started to appear in restaurants, stores, and movie theaters and places that had A/C found they were drawing in customers desperate to escape the heat and humidity outside.
Central air conditioning systems which used just one unit to cool an entire apartment, home or office was developed during the 1930s. That same period also saw the introduction of smaller units designed to cool down just one room or a single area. Some homes enjoyed the luxury of air conditioning after World War II, and another development was a system that combined the cooling and the heating unit. These increasingly began to appear in people’s homes and public buildings during the 1940s and ’50s.
So How Does Air Conditioning Work?
Rather like your refrigerator, air conditioning works by using a cooling substance (a refrigerant) to expand and remove the heat from the air. The heat is removed, rather tan cold air added to the air, which is what some people think. A machine is often used to cool the water in schools, public buildings and other large spaces. That cooled water is then delivered through pipes to a set of coils, and the resulting cooler air is then distributed through the building by means of vents and blowers.
One of the most important and useful parts of any air conditioning system is the thermostat. This regulates the temperature to prevent it fluctuating; without it you would find yourself turning your A/C unit on and off constantly to avoid too cold or too hot air. The cooling unit is switched off and on as it is needed, once you have your preferred temperature programmed into your thermostat.
A thermoelectric system is comprised of a number of semiconductors that are installed in pairs. When direct current flows through these pairs, known as couples, they are able to produce heat at one end and cool air at the other end. The heating and cooling effects are reversed when the current is switched to travel in the other direction and the whole thing is called the Peatier effect. This type of unit has a couple of big advantages; it’s extremely quiet and it’s also very small. In the future, this method of cooling will probably be commonplace for every household, although until then we are stuck with the noisier and larger air conditioning units.