Ask an Engineer: Air Conditioner Efficiency Ratings
What's the difference between SEER and EER ratings for air conditioners?
The seasonal energy efficiency ratio (SEER) and energy efficiency ratio (EER) are cooling efficiency measurements for air conditioning systems and heat pumps. Residential units are most often rated using SEER, while commercial-size air conditioners are normally rated with EER.
EER is a measure of how efficiently a system will perform at a specific temperature setting—typically 95°F. It's calculated based on the amount of British thermal units (Btu) per hour of cooling provided for each watt of power used. For example, if a system provides 12,000 Btu per hour of cooling and draws 1,200 watts of power, the EER rating is 10 (12,000 Btu / 1,200 watts = 10).
SEER measures how efficiently a cooling system will operate over an entire cooling season, as opposed to a single outdoor temperature. SEER ratings vary, depending on the climate region. SEER is calculated based on the total amount of cooling (in Btu) the system provides over the entire season, divided by the total number of watt-hours of electricity it uses.
For both measures, a higher rating means a more efficient system. SEER, however, provides a more accurate assessment of overall efficiency since it's measured using multiple temperature and humidity levels that reflect real climate conditions.
Optimizing the performance of your new air conditioning system involves more than just selecting the most efficient unit available. You must look at different types of systems and make sure the unit is sized correctly to fit your needs.
If you decide to move forward with a high efficiency heat pump or air conditioner, be sure to reach out to a SWEPCO-approved contractor. Our participating contractors can install the new unit and see if you’re eligible for a SWEPCO energy efficiency incentive to help cover the cost!
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