What is Room Air Conditioning?

Dana Hinders
Dana Hinders

Room air conditioning, also known as window air conditioning, is a good alternative to central air conditioning for renters who live in older homes or those who have only a small space to cool. Additionally, even though they cost more to operate, room air conditioning units are attractive to those on a tight budget because they have a lower up-front cost. Room air conditioning units can be purchased for as little as $200-$300 US Dollars (USD), while central air conditioning systems cost thousands of dollars to install.

A room air conditioner.
A room air conditioner.

Window air conditioner units can be purchased at any home improvement store. Although it's natural to assume that bigger is always better, many people make the mistake of purchasing air conditioning units that are too large. If the unit you choose is too large, it will cycle on and off more often than necessary. This will wear down the machine faster and result in a higher energy bill for you. To determine what size of air conditioner you need, look at the size of the area to be cooled. For small rooms of 100 to 150 square feet (30.48 to 45.72 square meters), 5,000 Btu's is sufficient. For a studio apartment of 900 to 1,000 square feet (274.32 to 304.8 square meters), however, you'll need a high-powered unit with 18,000 Btu's.

When looking for room air conditioning units, consider purchasing a product that is ENERGY STARĀ® qualified as having met the guidelines set by the US Environmental Protection Agency and the US Department of Energy. These products use 10 percent less energy than conventional room air conditioning units and often include features such as timers that allow for better temperature control when you're away from your home during the day. In this way, ENERGY STARĀ® products help prevent global warming while saving you money on your home cooling costs.

Ask a friend to help you install your unit, since many room air conditioners weigh 100 pounds (45.36 kilograms) or more. The unit must be stable and weather stripping should be applied around the area to keep outside air from entering your home. Placing the unit in a shaded location is recommended whenever possible, since this will help it operate more effectively.

Once your room air conditioning unit is installed, remember to replace the filters and coils as recommended by the manufacturer. A thorough cleaning is needed once per year to remove dirt, bugs, and leaves. Room air conditioners are louder than central air conditioning systems, so noise does not necessarily mean the unit is broken. However, if you notice it is also cycling on and off too frequently, repairs may be needed.

Dana Hinders
Dana Hinders

Dana holds a B.A. in journalism and mass communication from the University of Iowa. She has loved being part of the wiseGEEK team ever since discovering the joys of freelance writing after her son was born. Dana also hones her writing skills by contributing articles to various blogs, as well as creating sales copy and content for e-courses.

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Discussion Comments


My daughter lived in a small apartment when she was going to college. This was in an older neighborhood where they had a lot of mature trees.

The apartments did not have central air, and the residents could put in portable room air conditioning if they wanted to.

My daughter thought she would try to go without it, but it was much too hot. It can be hard to study and focus when you are sweaty and irritable.

My husband installed a window air conditioner for her which cooled off her whole apartment. One important thing is to make sure the weather stripping is tight around the unit. This can really help keep the hot air from coming through any cracks.

When she moved into her next place that had central air, she was not sad to give up her window air conditioning. Central air is more convenient and much quieter.


We used single room air conditioning in our house when we were kids. We had a lot of shade around our house, so the downstairs stayed pretty reasonable. I mostly grew up with no air conditioning and the windows open.

We had 2 bedrooms in the house and they were upstairs, and it could get pretty hot and stifling up there in the summer. For many years we just used fans at night, but finally got a couple of window air conditioners.

This really made sleeping upstairs so much nicer. The window in one bedroom was in the direct sun and you could tell this unit had to work harder.

The biggest advantage for us was we usually only ran these at night, so the sun wasn't as much of a factor as it would be during the heat of the day.


My son is a mechanic and is always working on something out in his garage. We found a used home air conditioner at a garage sale that was pretty cheap.

It ran good, so we gave it to him and helped him install it in his garage. This makes all the difference in the summer when it is too hot to work outside without some kind of air conditioning.

He could still work out in his garage without it, but it sure makes it a lot more pleasant when you aren't sweating just standing in one place.


There are many situations when single room air conditioning units can come in handy. They are also less inexpensive than installing central air in most cases.

We have a finished bedroom above our garage that I use as a guest room. It would have cost us a lot of money to install a central air unit just for this purpose.

Because this room does not get used that often, it was cheaper to go with a window unit. The room is not that big, so it cools off quickly.

One disadvantage to them is that they are louder than a central air unit, and you will definitely hear it cycling off and on.

Most people get used to this after awhile and don't even notice it. If I didn't have this room air conditioning system, I would not be able to use this bedroom in the summer time.

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