What is EER / EER2?
EER (Energy Efficiency Ratio) measures cooling efficiency at one fixed, hot condition — 95°F outdoors — rather than averaged across a mild season the way SEER is. It's the sterner test of how a system performs when the weather is actually punishing.
Why it matters in Arizona
For Phoenix-area buyers, EER2 is arguably more honest than SEER2: our cooling load is concentrated in exactly the extreme conditions EER measures. When comparing systems for the desert, look at both numbers, not just the big SEER2 on the brochure.
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