Air conditioner efficiency is marked on the side off all units as a number called the EER (Energy Efficiency Rating). The Energy Efficiency Rating is a ratio of the BTUs of the unit to the amount of power it consumes in Watts. That means that an air conditioner with 10,000 BTU capacity and an EER of 10 consumes 1000 watts of power. That’s quite a lot of juice.

The government mandates that all window units have a EER of at least 9.0. That said, there are a number of affordable units available with ratings of 10.5-11. These more efficient units will also have an Energy Star label on them because they exceed the minimum standard (9.0 EER) by at least 15%.

Keep these factors in mind when and if you must buy an air conditioner. There are a lot of alternatives to air conditioning – check out this article on How to Cool Your Home Without Air Conditioning for some great ideas and tips.