Buying a window air conditioner with enough power to cool the space you want cooled and then installing it correctly is essential for your comfort and conserving energy.
A room air conditioner that is too small struggles to cool the room, while a room air conditioner that is too big cools too quickly to lower the humidity. Both waste energy because they can’t work at peak efficiency.
Window air conditioners range in cooling size from 5,000 to 15,000 BTU. (One BTU is enough energy to raise the temperature of 1 pound of water by 1 degree F).
Here's the formula for computing how many BTUs to buy:
Multiply the square footage of the area to cool by 20 BTUs.
If more than two people regularly occupy the area to cool, add 600 BTUs for each additional person.
If the room is very sunny, add 10 percent to the total. If the room is heavily shaded, subtract 10 percent from the total.
If the room is the kitchen, add 4,000 BTUs.
