Heat Pump COP (Coefficient of Performance) Calculator

COP stands for Coefficient of Performance — the ratio of heating or cooling output to electrical energy input. COP = Heat Output (kW) / Electrical Input (kW). A COP of 4 means for every 1 kW of electricity, you get 4 kW of heat. COP varies with temperature: at 47°F (8°C) outdoor / 70°F indoor, a good air-source heat pump achieves COP of 3.5-4.5. At 17°F (-8°C), COP drops to 2.0-2.5. At -13°F (-25°C), COP may be 1.0-1.5. Ground-source (geothermal) heat pumps maintain COP of 3.5-5.0 year-round because ground temperature stays constant at 50-60°F (10-15°C).

COP decreases linearly with outdoor temperature. For air-source heat pumps: COP ≈ 0.11 × T_outdoor(°F) + 1.5 (approximate). At 50°F: COP ~ 4.0. At 30°F: COP ~ 3.0. At 10°F: COP ~ 2.0. At -10°F: COP ~ 1.3 (similar to resistance heating). Modern cold-climate heat pumps use variable-speed compressors and enhanced vapor injection to maintain COP > 2.0 down to -13°F (-25°C). The temperature lift (difference between indoor and outdoor) is the key variable — smaller lift = higher COP. Each degree of lift reduces COP by about 2-3%. Defrost cycles also reduce effective COP in cold humid conditions by 5-10%.

Minimum ENERGY STAR requirement: ≥ 2.2 COP at 47°F. Good: 3.5-4.5 COP at 47°F. Excellent: > 4.5 COP at 47°F. For cold climate: ≥ 1.8 COP at 5°F (-15°C) for Energy Star Cold Climate designation. Ground source: 3.5-6.0 COP at standard rating conditions. Ducted mini-splits often achieve the highest COPs (up to 5.5) because they avoid duct losses. As of 2024, the most efficient residential heat pump (Gree Flexx) achieves 4.8 COP at 47°F and 2.1 at 5°F. For comparison, electric resistance heating has COP = 1.0, natural gas furnace efficiency is 80-98% (COP 0.8-0.98).

Operating cost = (Heat Load / COP) × Electricity Rate. For a home needing 40,000 BTU/h (11.7 kW) heat: Electric resistance (COP 1.0): 11.7 kW × $0.12/kWh = $1.40/hr. Heat pump at COP 3.5: 11.7 / 3.5 × $0.12 = $0.40/hr. Heat pump at COP 2.0: 11.7 / 2.0 × $0.12 = $0.70/hr. In heating season (2,000 hours): COP 3.5 = $800/year vs resistance = $2,800/year. vs natural gas at $1.50/therm (80% furnace): $0.64/hr = $1,280/year. Heat pump saves 70% vs electric resistance, 37% vs gas (at current rates). Break-even COP vs gas: when COP > Gas Price / (Electricity Price × Furnace Efficiency).