SEER (or the current SEER2 standard) gets most of the attention when people talk about AC efficiency, but EER is a related, distinct measurement that's worth understanding, especially somewhere with as much sustained extreme heat as North Texas.
What SEER actually measures
SEER, seasonal energy efficiency ratio, measures a system's cooling efficiency across an entire cooling season, accounting for the full range of temperatures a system typically experiences over that time, from mild spring days to the hottest days of summer. It's a broad, averaged efficiency measurement.
What EER actually measures
EER, energy efficiency ratio, measures efficiency at one specific, fixed outdoor temperature, typically a hot one, rather than averaged across a whole season. In practice, this makes EER a more direct indicator of how efficiently a system performs specifically during the hottest days, which is exactly when North Texas homeowners actually need their AC working hardest and paying the most attention to their electric bill.
Why this distinction matters here specifically
Two systems with an identical SEER rating can have meaningfully different EER ratings, meaning one performs more efficiently than the other specifically during extreme heat, even though their seasonal averages look the same on paper. In a climate where summer heat is sustained and severe rather than occasional, EER is worth asking about alongside SEER2, not just relying on the seasonal number alone.
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