As a homeowner in Charleston, South Carolina, you want to be certain that your heating and cooling system is as efficient as possible. When choosing a new system, you’re likely to read about both SEER and EER ratings, and understanding the difference between the two will help you choose the right system for your home. Learn the difference between SEER and EER ratings so that you can ensure maximum efficiency and effectiveness of your heating and cooling system.

What Does EER Mean?

When you’re shopping for an air conditioning system, you’ll likely come across something called an Energy Efficiency Ratio (EER). The EER basically indicates the efficiency of a given air conditioning unit. To calculate this rating, the amount of electricity the AC uses is divided by how much cold air it puts out.

The benefit of the EER is that it measures how effective an air conditioner is at cooling a home when the outside temperature is at a certain level. For instance, an air conditioner’s EER is typically calculated assuming a consistent outdoor temperature of 95 degrees Fahrenheit.


The Seasonal Energy Efficiency Ratio (SEER) is used to indicate how efficient an air conditioner will be at a range of temperatures. Basically, this means that the SEER is an average rating, giving you an idea of how much energy your AC unit will use throughout the warm months. Where the EER is calculated using a steady temperature, the SEER is determined using a range of outdoor temperatures between 65 degrees and 104 degrees Fahrenheit.

When many homeowners choose their air conditioner, they tend to look at the SEER number. On the other hand, AC professionals prefer the EER because it gives a better idea of how a unit will perform under stressful conditions. For instance, in a city like Charleston, where high summer temperatures above 95 degrees are common, the EER is the more accurate rating.

If you need help choosing a new, efficient air conditioner for your home, call AC Heating and Air Conditioning Services today at (843) 277-9928. We’ll make sure you get exactly the right system for your home and family.

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