Many people mistakenly buy larger air conditioning units than they need because they believe that a larger unit will both operate and cool their house more efficiently. In truth, a larger unit could be less efficient.

What Size Air Conditioner Do I Need?

Mary Mattoon | Split Air Conditioning

What Do I Need to Know?

While bigger may be better in many instances, this does not hold true when it comes to air conditioning units. Many people mistakenly buy larger air conditioning units than they need because they believe that a larger unit will both operate and cool their house more efficiently. In truth, a larger unit could be less efficient. A larger unit may raise operating costs while inefficiently and ineffectively cooling and removing humidity from the home.

Why Does Square Footage Matter?
The square footage of the home is the best indicator of the size of air conditioning unit the home will need. Each room will need to be measured for square footage. If the room is square or rectangular, multiply the length of the room by its width to get the room's square footage. If the room is triangular in shape, multiply the length of the area by its width then divide this number by 2. This will give you a rectangular room's square footage. When the square footage of the rooms to be cooled has been calculated, the number of BTU's needed can be determined.

What are BTU's?
BTU's (British Thermal Units) indicate how much heat it will take to elevate the temperature of one pound of water by one degree Fahrenheit. BTU's are the method used to designate the capacity of residential air conditioners or their cooling capacity. The number of BTU's needed to cool the home will be directly related to square footage. If the square footage to be cooled is 400 to 450, then a 10,000 BTU air conditioning unit will be needed. If the square footage is 2,000 to 2,500, a 34,000 BTU system will be required.

Other Factors to Consider
While square footage is the main indicator when determining air conditioner size, there are other factors that need to be taken into consideration as well. For example, if a room is heavily shaded cooling capacity can be reduced by 10 percent. If the room is sunny, the cooling capacity will need to increased by 10 percent. How many people live in the home, how often people are in the home, types of ceilings in the home, the number and location of windows and doors, and the climate in which the home is located will all play a role in air conditioner size.

Potential Savings
In mid states using a standard split air conditioning system of 24,000 BTU may consume 2,474 KWh a year. This will cost \$174. Choosing the right size (as the article states) may reduce this by 10% (nearly 230 KWh less a year).

Mary Mattoon writes for Split Air Conditioning, her personal hobby blog focused on tips to consume less energy using
home air conditioning.