What is Central Air Conditioning?

Mary McMahon
Mary McMahon

Central air conditioning is a method of structural cooling in which a centralized unit cools and dehumidifies air before circulating it throughout a building. This is in direct contrast with systems that rely on individual units in rooms or suites of rooms. Central air, as it is also known, is often bundled with a heating system, as both rely on similar amounts of electrical power and ductwork to distribute cooled or heated air. This type of air conditioning is generally seen in large structures, or in homes in extremely hot, humid climates.

Central air conditioning systems relay on air ducts to transfer cool air to an area.
Central air conditioning systems relay on air ducts to transfer cool air to an area.

With central air, the main unit is often located outdoors or in an isolated area of a building because a great deal of noise is generated during the refrigeration cycles that cool the air and help to extract humidity. The unit connects to ductwork that runs throughout the building, with blowers pushing cold air out of the ducts to cool down rooms. The air conditioner also vents to the outdoors to get rid of excess heat and moisture.

An air conditioning vent.
An air conditioning vent.

Ductless air conditioning can also be used to cool air in large areas, but instead of relying on ductwork, it uses individual wall units that pull out moisture and hot air, and pump in cool air. This form of air conditioning can be more environmentally friendly, as people can control the climate in individual rooms or groups of rooms, rather than using a single central unit to maintain a desired temperature. Because temperatures can vary considerably across a structure, central air conditioning can use a lot of energy in its attempt to keep the air comfortable.

For large buildings, central air conditioning is critical, because the air can grow quite oppressive, especially in warm weather. Heat from the weather can make the building warm up, as can the heat from the bodies in the building, and moisture also accumulates as a result of respiration. Using central air will keep a building comfortable for people to work in and make it more pleasant for visitors who may be entering the building, such as customers entering a department store.

Homes in hot climates may also benefit from central air. Using this type of air conditioning system eliminates the need for wall or window units, which are often unsightly and can be difficult to manage. Central air, much like central heat, can also be calibrated to keep temperatures within a stable range while retaining energy efficiency. This is especially true when central air or heat is combined with measures such as insulating a home to help it resist external temperature changes and designing a home that is suited for its climate.

A central air conditioning unit.
A central air conditioning unit.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

You might also Like

Readers Also Love

Discussion Comments


How difficult is installing central air conditioning in an old home?

My mom is getting older and doesn't have it and it really concerns me. Is this a job that I could do myself with moderate skills as a handyman? How much would it cost?

I was in Denver over the summer and it was unseasonably hot. Most of the homes and buildings around there do not have central air conditioning because it never gets hot enough to need it. But with temperatures around 100 degrees, you really needed it. It was a particularly sweaty visit.

You want to have your world rocked about central air conditioning? Go to Hong Kong. I lived in HK for a few years, and one thing that absolutely blew my mind about the air conditioning there was that they put it on all the time. Literally, all the time.

As in, all through winter, on cold, rainy days, literally all the time. And I know it doesn't seem like it, but Hong Kong actually gets cold during the winter, so imagine walking into an air conditioned classroom out of 40 degree weather. Now, that's not atrociously cold on its own, but when you are in AC all the time it gets pretty bad. Apparently, according to my friends, its because they think that if you close the door without some form of AC going, then you could suffocate.

So just remember that next time you're enjoying your Trane central air conditioning system -- you could be enjoying in in the middle of winter too!


I think that I would literally die without my residential central air conditioning. I work outside most of the day, so I can stand for a lot of temperature derivation, but having that nice, cool area to walk into after a long day is just heaven.

I'm just glad that central air conditioning doesn't cost too much these days. I know when my parents were going up the central air conditioning installation prices were through the roof, not to talk about the cost of running the thing!

Now we've got all these fancy ductless central air conditioning systems and what not -- I can only imagine what my dad would have said about that! So how about it, am I the only air conditioning addict out there, or are there others among us?


I know I'm going to sound like a terrible old fogey for saying this, but when I was growing up, we didn't have any central heating or air conditioning -- and we lived in southern Georgia.

Now, you can talk about how miserably hot it gets nowadays, but when you're in a small house down near the Florida line with three other children, two parents, and an assortment of pets, that is truly hot.

We never even dreamed of having the nice climate controlled central air conditioning systems that they have today, we just took cold baths when we could and stayed still a lot.

And do you know the worst part that I remember? It was not so much the being hot as the laundry. Since everybody was sweating so much, we had to do laundry almost constantly, it seemed like, and that just made you even more hot. By the time you finished doing the laundry, you needed to wash the clothes that you did the laundry in!

So just remember, (at the risk of sounding old again), be grateful for what you've got -- and the fact that you don't have to do laundry by hand in 100 degree weather!

Post your comments
Forgot password?