Heat Pump COP and Efficiency Calculator
Calculate the Coefficient of Performance (COP), Heating Seasonal Performance Factor (HSPF), and Energy Efficiency Ratio (EER) for heat pumps operating in heating and cooling modes.
Operating Temperatures
Power & Heat Transfer (Optional)
W
Electrical power consumed by the compressor
Formulas Used
Carnot COP (Heating Mode):
COPH,Carnot = TH / (TH − TC)
Carnot COP (Cooling Mode):
COPC,Carnot = TC / (TH − TC)
Actual COP (from measured values):
COPactual = Q / Win
Where Q = heat delivered or removed (W), Win = electrical power input (W)
Carnot Efficiency:
ηCarnot = COPactual / COPCarnot × 100%
Energy Efficiency Ratio (EER, cooling):
EER = QBTU/hr / Win,W [BTU/(hr·W)]
Heating Seasonal Performance Factor (HSPF):
HSPF ≈ COP × 3.41214 [BTU/(hr·W)] — steady-state approximation
All temperatures must be in Kelvin (absolute scale) for thermodynamic calculations.
Assumptions & References
- Carnot COP represents the theoretical maximum efficiency for a reversible heat pump operating between two fixed temperature reservoirs (Second Law of Thermodynamics).
- Temperatures are converted to Kelvin (K = °C + 273.15) before applying thermodynamic formulas.
- Actual COP is calculated from steady-state measured power input and heat transfer — does not account for startup losses, defrost cycles, or part-load operation.
- HSPF (Heating Seasonal Performance Factor) is the U.S. DOE standard metric for heating efficiency; minimum federal standard is 8.2 HSPF (as of 2023).
- SEER (Seasonal Energy Efficiency Ratio) is the U.S. DOE standard for cooling; minimum federal standard is 14 SEER (northern U.S.) / 15 SEER (southern U.S.) as of 2023.
- EER conversion: 1 W = 3.41214 BTU/hr.
- Real heat pumps typically achieve 40–60% of Carnot COP due to irreversibilities (friction, heat transfer across finite temperature differences, compressor inefficiency).
- References: ASHRAE Handbook — Fundamentals (2021); Çengel & Boles, Thermodynamics: An Engineering Approach, 9th ed.; U.S. DOE ENERGY STAR Heat Pump Program.