Customer Question: What’s The Difference between EER and SEER?

We’re fortunate in maintaining great communications with our many air conditioning customers. Few other HVAC contractors can say they have customers writing to them regularly to thank them for their hard work on an air conditioning repair or installation. But this is a routine occurrence for us. We want to be a hero to our customers, and usually succeed.

Of course, excellent communication with a customer allows us to help them better. We often receive questions from customers about how HVAC equipment operates and what’s important for them to know about them. We want to pass on some of this knowledge to you, such as the difference between the two efficiency ratings found on air conditioning systems, EER and SEER. Almost all AC units have these two ratings listed, but what do they mean and what separates the two, aside from the letter S?

Measuring Air Conditioning System Efficiency

First, we have to explain how the energy efficiency of an AC unit is measured. Efficiency explains how effectively an air conditioner changes electrical power into cooling power. Cooling power is described as the amount of heat removed from the air. (ACs don’t “create” cooling, they subtract heat.) The ratio of the amount of heat removed in BTUs (British Thermal Units) to the amount of energy used in watt-hours to achieve it is the air conditioner’s efficiency ratio. But the way the tests are conducted to determine the ratio is what separates EER and SEER.

EER vs. SEER

EER stands for energy efficiency ratio, and it’s the standard ratio (BTUs to watt-hours) as measured under a specific set of conditions over a single test. The conditions are 85°F indoor temperature, 90°F outdoor temperature, and 50% humidity. What we might call a peak summer day for most of the country.

SEER, on the other hand, stands for seasonal energy efficiency ratio, and its BTUs-to-watts ratio is calculated over an entire season of handling heat. The conditions the air conditioner runs under range from 65°F to 104°F and an equally wide humidity range. EER gives you a spot look at efficiency; SEER offers a panorama.

Choosing a New Air Conditioning System

If you’re planning to use this spring to install a new air conditioning system in Marietta, GA, you’ll probably wonder what SEER/EER rating is best. We recommend you always choose an AC with the ENERGY STAR label from the U.S. Department of Energy. To earn this label, an air conditioning unit must have a minimum SEER/EER of 15/12.5. There are units that score higher, but as efficiency goes up, so does unit cost.

The best way to choose the air conditioning system ideal for your household’s cooling needs and your budget is to let our HVAC professional guide you. It’s important to note that a high SEER/EER number doesn’t automatically mean a system that saves money. The air conditioner must also be properly sized and installed—and this is where our professionals are invaluable.

Comfort Zone Heating & Cooling serves Cummings, GA and all of North Atlanta. Call our customer service specialists at 770-213-COOL (2665) and let us know how we can help.