The calculation
Annual cooling energy equals rated capacity multiplied by equivalent full-load cooling hours, divided by the efficiency rating. Your actual runtime and part-load performance will change the bill.
Compare annual cooling electricity use, operating cost, and the simple payback on an efficiency upgrade.
1,620 fewer kWh per year · 37.5% less cooling energy
Annual cooling energy equals rated capacity multiplied by equivalent full-load cooling hours, divided by the efficiency rating. Your actual runtime and part-load performance will change the bill.
They use different test procedures. Do not directly compare a SEER number with a SEER2 number. Use two ratings measured under the same standard.
Compare the energy saving with the additional installed cost—not the full replacement price. Comfort, humidity control, warranties, incentives, and expected ownership period also matter.