How to Calculate the Cost of Cooling

A quick math lesson will help you anticipate and plan your cooling costs.
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If you don’t want to wilt in the summer heat, the obvious solution is to install air conditioning in your home. It’s a good idea to calculate the cost of cooling before you proceed so you can plan and prepare your finances for the expense you’ll incur. With some key information and a few basic mathematical equations, you’ll soon know exactly what to expect when that once-dreaded cooling bill arrives.

Step 1

Check the yellow “Energy Guide” sticker on the air conditioner unit or read the manual to find information on the capacity and seasonal energy efficiency ratio of the unit. The capacity measurement will be in BTUs (British Thermal Units) and the seasonal energy efficiency ratio number will probably follow the acronym “SEER.” You need both of these numbers to do the math.

Step 2

Consult a map to find out what the cooling load hours are for where you live. Visit the Louisiana Department of Natural Resources website (see Resources) for a map that will help you figure your cooling load hours, if necessary. Find your location on the map and note the number assigned to your geographical location.

Step 3

Check out a recent electricity bill or call your electric company to find out your current electric rate. Make sure this rate includes fuel adjustment charges and any local taxes (use average figures for the summer months).

Step 4

Divide the BTUs by the SEER number. Multiply the answer by the cooling load hours for your location. Divide your answer by 1,000. Multiply your answer by your electric rate. The answer is your annual cost of cooling. For example, if the BTUs of your unit are 36,000, the SEER number is 10.5, your cooling load hours are 600, and your electric rate is .092, your process would be 36,000 divided by 10.5, or 3,428.57. Multiply 3,428.57 by 600 to equal 2,057,142.80. Divide 2,057,142.80 by 1,000 to equal 2,057.14. Multiply 2,057.14 by .092 to equal $189.25. This represents your annual cost of cooling.

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