The Energy Efficiency Ratio (EER) provides consumers with key information when shopping for an air conditioner. EER rates HVAC units on how efficiently they cool indoor air. To determine this rating, an air conditioning unit’s British thermal units (BTU) are divided by its wattage.

EER is essentially a single rating point to determine the HVAC’s cost of operation and is primarily for warmer climates due to the high demand for cool indoor air. Many air conditioner manufacturers elect to participate in the ENERGY STAR labeling program which indicates a high EER rating if the appliance is stickered.

When determining which EER rating is right for you, it’s important to take into account where the air conditioner will be installed. For example, an office might run the air conditioning unit more than a home or vice versa. Finding a unit with the proper EER ratings will help efficiency costs in the end.