Geothermal Heat Pump (COP) Calculator

Estimate the Carnot and realistic coefficient of performance of a geothermal heat pump from source and sink temperatures and a practical efficiency factor.

Heating side temperature T_hot (°C)

Source side temperature T_cold (°C)

Practical efficiency vs Carnot (%)

How to Use the Geothermal Heat Pump (COP) Calculator

Enter the hot-side (space-heating) supply temperature in °C.
Enter the cold-side (ground loop) source temperature.
Enter the practical efficiency as a percentage of Carnot.
Click Calculate.

使用场景

•Sizing ground-source heat pumps.
•Energy audits.
•Teaching the second law of thermodynamics.

公式

COPcarnot = T_hot / (T_hot − T_cold) with temperatures in Kelvin. Real COP = COPcarnot × practical efficiency.

常见问题

Why is real COP lower than Carnot?

The Carnot value is the thermodynamic limit. Real compressors, heat exchangers, defrost cycles and refrigerant pressure drop cost typically 35–55% of that maximum.

What practical percentage should I use?

Modern brine-to-water heat pumps reach about 45–55% of Carnot at the seasonal operating point. Older units and large ΔT conditions drop to 30–40%.

Is COP the same as EER?

COP is used for heating, EER/SEER for cooling. They use the same temperature-difference logic but different reference states.