% savings=1-SEERcurrentSEERcurrent*100% *only applies if rated cooling output and operating schedules remain the same after upgrade, otherwise energy consumption in kWh must be calculated separately for existing and projected running conditions
R-410a: New standard, more efficient, no ozone damage, operates at higher pressures, requiring use of tougher and more durable parts, increasing life of system.
R-22 (freon): Old standard, now illegal in any system manufactured after 2010, no longer imported or manufactured after 2020. Less energy efficient (absorbing and releasing heat), contributes to depletion of ozone, rising prices.
Efficiency: ratio of cooling output (BTU) to heating input (watt-hours) (unit = BTU/Wh)
Energy Efficiency Ratio (EER): fixed set of operating conditions (Tindoor = 80F, Toutdoor = 95F, relative humidity = 50%)
Seasonal Energy Efficiency Ratio (SEER): averages performance across a range of outdoor temperatures typical of the cooling season.
Estimated Capacity: BTU/Hr
US DOE: 3% degradation for unmaintained, 1% for completely maintained systems