Electrical Load
The first step to determine the cost of running an air conditioner is to derive the electrical load by multiplying the operating hours by the wattage the air conditioner uses. This yields the overall energy use of the appliance. This value, multiplied by the cost of electricity in the area, yields a good approximation of standard operating cost. The wattage may be available on the air conditioner itself, or it can be obtained by multiplying the amps by the voltage.
Electrical Pricing
Most large utilities stagger the pricing of their electrical service throughout the day or year. For example, in the summer peak hours, electricity prices often rise to cover the cost of peak usage. An air conditioner often is used during these hotter hours. The pricing model of the electrical company greatly affects the overall cost of operating an air conditioner. This cost may vary widely, all other things being equal, among regions.
Work Load
The more heat the air conditioner has to vacate from the home, the harder it must work. The compressor within the air conditioner will be running continually to work against the heat gradient it is creating. The hotter the temperature outside the home, the longer and harder the air conditioner must work to maintain a specific temperature inside. A 5000 BTU air conditioner, by most standards, is qualified to cool one small room. This causes all other interior walls to leak heat into the room from within the home as well.
Installation and Maintenance
Depending on the location desired for installation of the air conditioner, an installer may be necessary. Installations that are not on the ground floor may require special mounting structures to be built for them. Permanent air conditioners, which only supply electrical leads and not standard wall plugs, will require an electrician as well. These costs are significant, especially if the appliance is of a permanent nature.
Example Calculation
Determine the wattage use of the air conditioner. Using the Crosley 5000 BTU window unit air conditioner as an example, with three hours of power usage a day at a wattage usage of 535 watts, the kW hours used is calculated as (kiloWatts x hours used) = (0.535 x 3) = 1.605 kWh. Using a 14 cent per kWh peak power cost rate, determine the daily cost by (kWh price x kWh usage) = (0.14 x 1.605) = 0.22 cents per day. Thus, the cost of using this specific 5000 BTU air conditioner in a 30-day month is $6.74.