What Is an EER Rating?

What Is an EER Rating?

The EER rating is what tells you how efficient your air conditioner really is.

If you are in the market for an air conditioner, you may have seen a number with EER next to it. This number indicates which machine might be of higher quality and better suited for your home. Among the appliances in a house, the air conditioner is essential for Maryland’s humid summers. Learn more here about what an EER rating is and how it can help your air conditioning choices.

The EER Rating

EER stands for Energy Efficiency Ratio. It measures how efficient the appliance is in generating cool air. In other words, it shows how much cooling power comes out of how many watts. The more British thermal units (BTUs) and the fewer watts, the more efficient it is, and the higher the EER rating is. Divide the BTUs by the watts, and you have the EER.

You can calculate further to see how much it will cost to operate the AC yearly. After dividing the BTUs by the EER number, you will get the wattage per hour. Multiply that by the cost of electricity, and multiply that by the average number of hours you will use it in the season. Then you will have the annual cost.


EER and SEER are the two most common air conditioner ratings. The problem with SEER ratings are that they are based on very moderate outdoor temperatures. Often, these temperatures are so moderate most homeowners would not be running their heating or cooling anyway. EER, on the other hand, is rated at half or high capacity. For example, if Bob purchases a new 18 SEER HP he is never going to actually run the unit at 18 SEER. So, Bob’s so-called 18 SEER will almost always be less than 18. An EER rating, however, gives you the rating at full  or half capacity; that means you see the efficiency that the unit will actually be running at most of the time. Therefore, if unit A has a SEER of 20 and unit B has an EER of 20, unit B will be running at 20 EER most of the time, but unit A will almost never run at 20 SEER. Unit B is far more efficient.

What Is the Best EER Rating?

EER is similar to SEER in this: the higher the rating, the more efficient the operation. Talk with your installing contractor to see what combination of budget and efficiency is best for your situation. An EER rating can mark up to 40EER. There is no direct conversion from SEER to EER; however, you can estimate a 28 EER geothermal unit is roughly 40 SEER.


If you are concerned about high electricity bills in the winter, consider investing in geothermal heat pumps to help alleviate some of those costs. With many experienced technicians available, Ground Loop Heating & Air Conditioning, Inc. can solve all your air conditioning system problems. If you are interested in creating the most comfortable environment for your family to enjoy, contact Ground Loop Heating & Air Conditioning, Inc.today.

You can reach us at 410-836-1706, or visit our website for more information! If you are interested in more information about geothermal heating and cooling systems, check us out on Twitter, YouTube, Facebook, and LinkedIn.

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