- EER = Cooling Capacity (BTU/hr) ÷ Power (W).
- COP = Useful Output (kW) ÷ Electrical Input (kW).
- Thermal efficiency = (Furnace Output ÷ Fuel Input) × 100.
- Seasonal COP = Annual Delivered (kWh) ÷ Annual Electric (kWh).
- W/CFM = Fan Power (W) ÷ Airflow (CFM).
- Estimated SEER = EER × 1.15 (rule-of-thumb only).
- Pick a mode that matches your test scenario.
- Enter complete pairs for the metric you need.
- Use consistent units within each pair.
- Press Calculate to show results above the form.
- Export CSV or PDF for commissioning and handover.
| Scenario | Cooling (BTU/hr) | Cooling Power (W) | EER | Heating Out (kW) | Heating Power (kW) | COP (heat) | Airflow (CFM) | Fan (W) | W/CFM |
|---|---|---|---|---|---|---|---|---|---|
| Packaged unit, measured | 36,000 | 3,200 | 11.25 | 12.0 | 3.8 | 3.16 | 1,200 | 650 | 0.54 |
| Retrofit with duct sealing | 30,000 | 2,700 | 11.11 | 10.5 | 3.3 | 3.18 | 1,100 | 500 | 0.45 |
Commissioning Inputs and Measurement Quality
Accurate efficiency values depend on measured capacity and power under stable conditions. Verify airflow, refrigerant charge, and clean filters before recording data. Use true RMS electrical readings for compressors, heaters, and fans. Log indoor and outdoor temperatures, humidity, and thermostat setpoints for traceable results. Where possible, confirm cooling output using calibrated airflow and temperature difference. Allow equipment to reach steady state before capturing numbers.
Interpreting EER and COP Together
EER compares cooling output to electrical input at a test point. COP compares useful output to input using the same power units. If both are calculated, check that they move consistently; mismatched units or transient readings distort comparisons. Field results vary with load, coil cleanliness, fan speed, and duct losses. For heat pumps, heating COP shows low ambient and defrost impacts.
Seasonal Performance for Energy Budgets
Seasonal COP and SPF divide delivered annual conditioning energy by annual electric consumption. These indicators support energy models, incentive forms, and owner forecasts. Prefer submetered kWh and separate auxiliary loads such as pumps and reheat. Normalize comparisons by degree days when only utility bills exist. Even small seasonal COP changes can affect operating cost and carbon reporting. Ensure delivered energy reflects space conditioning.
Airflow and Fan Power Implications
Fan W/CFM exposes distribution efficiency in the field. High W/CFM suggests restrictive ductwork, poor balancing, undersized returns, or dirty coils. Lower static pressure through better layout, sealing, and appropriate grille selection can cut fan energy and improve comfort. Measure airflow and fan power at the same operating mode so the ratio reflects real performance. Confirm dampers, filters, and registers are not blocking the designed airflow path.
Construction Closeout and Documentation
During closeout, package calculated metrics with nameplate ratings and corrective actions taken. Attach commissioning checklists, as built notes, and measurement conditions to speed future troubleshooting. Exported CSV and PDF reports standardize handover across multiple buildings and trades. Recheck efficiency after control tuning, occupancy changes, or major maintenance to preserve performance.
What inputs are required to calculate EER?
Enter cooling capacity in BTU per hour and measured electrical power in watts. Use steady operating conditions and consistent readings to avoid inflated EER values.
Can I calculate COP using only kW values?
Yes. Provide useful heating or cooling output in kilowatts and the matching electrical input in kilowatts. The calculator reports COP as output divided by input.
Why does seasonal COP differ from nameplate ratings?
Seasonal COP reflects real operating hours, weather, controls, and auxiliary loads. Nameplate ratings come from standardized lab tests that may not match field conditions.
What does a high W/CFM typically indicate?
It usually points to high static pressure from duct restrictions, poor balancing, dirty coils, or undersized returns. Lowering pressure reduces fan energy and noise.
How should I use the overall efficiency score?
Treat it as a quick internal benchmark. It averages available metrics after simple normalization, so it helps compare scenarios, but it does not replace certified ratings.
Does this calculator replace commissioning and test reports?
No. It supports calculations and documentation, but commissioning should still verify airflow, controls, safety checks, and performance across operating modes.