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What is EER?
EER, or energy efficiency ratio, measures how efficiently an air conditioner or heat pump cools your home at a specific outdoor temperature and indoor condition.
EER, or energy efficiency ratio, measures how efficiently an air conditioner or heat pump cools your home at a specific outdoor temperature and indoor condition. It’s calculated by dividing the cooling output (in British thermal units, or BTUs) by the electrical power input (in watts) at that single test point. A higher EER means the equipment produces more cooling for each unit of electricity it uses, which generally translates to lower operating costs during hot weather.
How EER differs from SEER
EER and SEER (seasonal energy efficiency ratio) both describe cooling efficiency, but they measure different things. EER reflects performance at one fixed, typically hot, outdoor temperature, while SEER reflects performance averaged across an entire cooling season with varying conditions. Because New Orleans summers stay hot and humid for long stretches, EER can give a useful snapshot of how a system performs during the peak-demand days when your air conditioner works hardest. Manufacturers publish both ratings on equipment specification sheets, and comparing them side by side gives a fuller picture than looking at either number alone.
Where you’ll see an EER rating
You’ll typically find EER listed on the manufacturer’s spec sheet or the unit’s rating plate, alongside SEER and other efficiency figures. If you’re shopping for a new system or reviewing paperwork from a past installation, ask your contractor to point out the EER value and explain how it applies to your specific equipment model, since ratings can vary by unit size and configuration even within the same product line.
What affects real-world EER performance
The EER printed on a spec sheet reflects laboratory testing conditions, not necessarily what happens in your home. Actual performance depends heavily on installation quality. Equipment that’s improperly sized, has unsealed or leaky ducts, or is undercharged or overcharged with refrigerant can run well below its rated efficiency, leading to higher bills and reduced comfort regardless of the EER number on paper. The Department of Energy’s guidance on quality HVAC installation outlines these factors, including correct equipment sizing, optimized airflow, proper refrigerant charge, and duct evaluation, as the practical steps that determine whether a system reaches its rated efficiency in real conditions.
Sources
- Department of Energy, accessed 8/12/2026
- HVAC Quality Installation | ENERGY STAR, accessed 8/12/2026
- Page not found | ENERGY STAR, accessed 8/12/2026