The first thing you need to do is measure the space that you want to cool. You need to know the square footage, which is easy to figure out. Just measure the floor. Measure in one direction and then measure in the other direction. Then multiply the two numbers. Ta-da! Square footage.
Now take your square footage and multiply that by 35. That will give you a general idea of what SIZE air conditioner to buy. That doesn’t mean how big in inches. It means how big in BTUs – British Thermal Units.
Every window air conditioner has a cooling capacity number that ranges from about 5,000 to 18,000 BTUs. (Larger systems are usually rated in tons of cooling with a ton being equal to 12,000 BTUs.) The higher the BTU value, the stronger the air conditioner is. BTUs determine how much cooling the unit can deliver in an hour. Too little BTUs and you won’t get cooled off. Too many BTUs and you will waste energy and MONEY – yikes!
For those of you living in high humidity areas here is a bit more insight: Many people buy an air conditioner that is too large, thinking it will provider better cooling. However, an over-sized air conditioner is actually less effective — and wastes energy at the same time. Air conditioners remove both heat and humidity from the air. If the unit is too large, it will cool the room quickly, but only remove some of the humidity. This leaves the room with a damp, clammy feeling. A properly sized unit will remove humidity effectively as it cools.
Once you determine your BTU need (square footage multiplied by 35), make sure that you make adjustments for room location and heat load:
- If the room is shaded, reduce the BTUs by 10%
- If the room is very sunny, increase the BTUs by 10%
- If the air conditioner is in the kitchen, add 4,000 BTUs
- If the room is going to be occupied by more than 2 people most of the time, add 600 BTUs per person
Another thing to consider is EER, which stands for Energy Efficiency Ratio.” Air conditioners’ EERs usually range from 8.2 to 10.5. The higher the number, the more efficient the machine and the more expensive to buy, but cheaper to operate. It’s a numbers game.
OK, so now that you know what size air conditioner you need, look on Craigslist. If you can’t find what you are looking for there, check out one of the big box warehouse stores like Sam’s Club, Costco, or BJ’s. They have competitive prices and their return policies are fabulous. Don’t buy an air conditioner online because the shipping cost will be enormous.
When installing your window air conditioner, use a window that is in the shade. Ensure that there is space around the inside and outside for air flow. In other words, don’t put the air condition up against the back of your couch or right up against a bush outside. Insulate where the window and air conditioner meet to make sure there is no air leakage around the unit and the window. Make sure that you clean the filters on a regular basis as this will increase the efficiency and life of your air conditioner.
OK, those are my tips. Good luck and stay cool.