Tuckers Air Conditioning, Heating & Plumbing Blog

Understanding What AC Efficiency Ratings Really Mean


If you’re reading this, it’s probably because you have plans to purchase a new central air conditioning system before the summer heat arrives. A good plan, especially if your current AC has shown signs its useful days are done and an AC repair in Frederick, MD won’t keep it running effectively.

But you came to this post seeking answers to a specific question you have about buying a new air conditioning system: “What do these efficiency numbers all mean?” For example, “What is SEER? Is higher or lower better? Is SEER 15 ‘good’? And what’s this EER thing? Please help, I can’t sleep at night!”

No problem—that’s what we’re here for. When it comes to making the actual selection and installation of a new air conditioning system, you’ll need our professional technicians on the job. For the moment, we can give you a basic rundown on SEER and EER and what to look for.

EER = “Energy Efficiency Ratio”

The base rating for cooling system efficiency is energy efficiency ratio (EER). This is a measure of the amount of cooling an air conditioner produces (i.e. the amount of heat it pulls from the air) compared to the electricity consumed as measured under a specific set of conditions (heat, humidity). EER is a ratio of the amount of cooling produced in BTUs to the amount of electricity used in watt-hours. The higher the number, the more cooling per watt-hours.

SEER = “Seasonal Energy Efficiency Ratio”

Although EER is the starting point for determining efficiency, the real data to focus on is seasonal energy efficiency ratio (SEER). The similarity of the names is because the two ratings are almost the same—with the important exception that SEER is determined over multiple tests and differing conditions, rather than a single test. SEER averages out the performance for an air conditioning system over an entire season of cooling, so it gives the consumer a better sense of how well the AC does each year.

What Are the Best SEER and EER Ratings?

Higher numbers are better in terms of raw efficiency. (By the way, EER is always lower than SEER for any model.) But better is a relative term. The highest-rated air conditioner with the top efficiency features may not be ideal for your house. The more efficient systems are more expensive to purchase, and high SEER/EER is not a guarantee of energy savings. For example, a poorly sized and installed air conditioner will end up wasting energy no matter how high its SEER rating.

However, we recommend getting units that at least meet the ENERGY STAR minimum for efficiency. This is 15 SEER/12.5 EER. Anything lower won’t meet requirements for base efficiency. A 15 SEER air conditioning system works well for many homes, and if this is the best choice for your household, we won’t pressure you to purchase a more expensive unit.

Get in touch with our air conditioning experts today to find out more about your AC options and what energy-efficient models may be right for your house.

Tuckers Air Conditioning, Heating & Plumbing serves Washington D.C., Montgomery & Frederick Counties. Schedule a new air conditioning installation today.