Convert a cooling efficiency between COP, EER (Btu/h per W) and kW/TR, and estimate SEER, for air conditioners, heat pumps and chillers.
12 EER =
3.517 COP
SEER is seasonal and EER a single rated point, so this is an estimate.
Coefficient of Performance
3.517 COP
Energy Efficiency Ratio
12 EER
Seasonal EER
≈ 14.44 SEER
Kilowatt per Ton
1 kW/TR
COP, EER and kW/TR convert exactly: EER = COP × 3.412 and kW/TR = 3.517 ÷ COP. SEER is a seasonal average, while EER and COP are rated at one condition (35 °C / 95 °F outdoors), so SEER ↔ EER is only an estimate, from EER ≈ 1.12 × SEER − 0.02 × SEER² (Wassmer, NREL, 2003), valid up to SEER 28. Use the manufacturer's rated EER and SEER where you have them. European EER and SEER (EN 14511, EN 14825) are in W/W, on the COP scale.