When shopping for a new window air conditioner, look for one with BTUs rather than amps or watts.

BTUs (British Thermal Units) is a global standard for determining the cooling capacity of an AC unit. It tells you how ample a space the AC unit can cool.

For example, a 10,000 Btu window air conditioner can cool a room of 20 feet by 22 feet.

However, this problem is that not all air conditioning units with the same BTU ratings use the same amount of energy to operate.

One 10,000BTU air conditioner can consume 900 watts of electricity, while another consumes 1,000 watts.

The total wattage depends on how energy efficient the manufacturers made the appliance.

How can you figure out how much wattage an air conditioner uses?

- Read the product manual.
- Look at the technical specifications on the manufacturer’s (advertising firm’s) site.

If you know the wattage of an air conditioner, you can calculate the cost per kilowatt-hour (kWh) you spend on electricity at home.

To calculate how much it will cost to operate the window air conditioning unit each hour, day, week, month, and during a whole year, use the following formula.