When you start the quest to have a new air conditioning system installed in your home (and right now is a good time to have it done; we’re coming up on the hot days of summer) you’ll encounter numerous numbers and stats. It can all be a bit confusing. You probably already know that BTUs has something to do with how much cooling an air conditioner can put out. The higher the BTUs, the more cooling power the AC has. Technically, BTUs are a measure of how much heat the AC can remove from the air—but the effect is the same as far your comfort is concerned.
But what about the two efficiency ratings you find on the list of an air conditioner’s stats, SEER and EER? You might know that the higher these numbers, the more energy efficient the air conditioner is. But what’s the difference between the two numbers? Why the extra “S” on SEER? What does it mean, and is it important?