When people speak of size in reference to air conditions, it doesn’t refer to the physical dimensions of the appliance itself, but rather it means the cooling capacity, as measured in BTUs (British Thermal Units). Whether you are choosing a window air conditioner or a central air unit, you will get the best efficiency, and therefore lower operating costs, if you choose based on the size of the area the unit must cool.
The cooling “size” of an air conditioner is measured in its ability to extract a certain amount of heat measured in British thermal units, or BTUs. A common mistake when buying a room air conditioner is purchasing a unit too big for the size of the room (i.e., too many BTUs).
Room air conditioner sizing is all about matching the room size to the air conditioner size. A unit that is too big will be less effective and offer reduced air conditioner efficiency. Air conditioners remove both heat and humidity from the air. If the unit is too large, it will cool the room, before it has a chance to remove the humidity. The result will be a room that’s not very comfortable to spend time in That cool moist air will make the room feel damp and clammy.
The most energy efficient air conditioner is sized to the square footage of the space to be cooled. Getting the right size means getting the comfort and the energy efficiency right.
1. Determine the room's square footage
2. Find the correct cooling capacity for your room size
With the cooling capacity chart, find your room’s square footage in the “Area To be Cooled (square feet)” column, then use the “Capacity Needed (BTUs per hour)” column to choose the correct cooling capacity for your room air conditioner. Cooling capacity is shown in British thermal units (BTUs) per hour.