Calculator Inputs
Enter measured or estimated heating performance data. Results appear above this form after submission.
Example Data Table
| Parameter | Example Value | Parameter | Example Value |
|---|---|---|---|
| Heating Output | 12 kW | Power Input | 3.2 kW |
| Sink Temperature | 35 °C | Source Temperature | 7 °C |
| Aux Heater | 0.4 kW | Cycling Factor | 1.05 |
| Defrost Loss | 6% | Distribution Loss | 4% |
| Seasonal Degradation | 10% | Runtime Hours | 8 h |
| Gross COP | 3.750 | Adjusted COP | 2.880 |
| Seasonal COP | 2.592 | Carnot COP | 11.005 |
| Delivered Energy | 86.630 kWh | Operating Cost | 5.41 |
Formula Used
1. Gross Heating COP
Gross COP = Heating Output ÷ Electrical Power Input
2. Effective Heat Output
Effective Heat = Heating Output × (1 − Defrost Loss) × (1 − Distribution Loss)
3. Effective Power Input
Effective Power = (Electrical Power Input × Cycling Factor) + Auxiliary Heater Power
4. Adjusted COP
Adjusted COP = Effective Heat ÷ Effective Power
5. Seasonal COP
Seasonal COP = Adjusted COP × (1 − Seasonal Degradation)
6. Carnot Heating COP
Carnot COP = Thot ÷ (Thot − Tcold)
Temperatures must be converted to Kelvin before using this equation.
7. Relative Efficiency
Relative Efficiency = (Adjusted COP ÷ Carnot COP) × 100
8. Operating Cost
Operating Cost = Effective Power × Runtime Hours × Electricity Rate
How to Use This Calculator
- Enter the delivered heating output and choose its unit.
- Enter the measured electrical input power and its unit.
- Provide sink and source temperatures in degrees Celsius.
- Add runtime hours and electricity rate for cost analysis.
- Include auxiliary heater power if backup resistance heat is active.
- Apply defrost and distribution losses for a more realistic net result.
- Use the cycling factor to reflect part-load or short-cycle penalties.
- Press Calculate COP to show the report above the form, then export it as CSV or PDF.
FAQs
1. What does COP mean for a heat pump?
COP is the coefficient of performance. It compares useful heating delivered to electrical energy consumed. Higher values indicate more efficient heating performance under the tested operating conditions.
2. Why is adjusted COP lower than gross COP?
Adjusted COP includes real-world penalties such as defrost losses, duct or hydronic distribution losses, cycling effects, and auxiliary heater use. Gross COP only compares headline output against headline electrical input.
3. Why compare with Carnot COP?
Carnot COP is the ideal thermodynamic limit for the chosen hot and cold temperatures. Comparing actual COP with it helps judge how close the system operates to an ideal reversible cycle.
4. Should temperatures be entered in Celsius?
Yes. Enter source and sink temperatures in Celsius. The calculator automatically converts them to Kelvin for the Carnot equation because thermodynamic temperature ratios must use an absolute scale.
5. What is a good residential heating COP?
It depends on climate and operating temperature. Many systems achieve roughly 2 to 4 in normal heating conditions. Colder source temperatures and higher sink temperatures usually reduce COP.
6. Why include auxiliary heater power?
Backup electric heat can sharply increase total power draw while adding less efficient heat. Including it gives a more honest picture of whole-system performance during cold weather or high-demand periods.
7. Can this calculator estimate operating cost?
Yes. Enter runtime hours and an electricity rate. The calculator estimates consumed energy and multiplies it by the rate to show approximate operating cost for the selected scenario.
8. Is seasonal COP the same as laboratory COP?
No. Seasonal COP is lower because it reflects weather changes, frost cycles, standby effects, and performance degradation across a longer period rather than a single controlled test point.