Calculation sequence
Step-by-step method
- Convert SI cooling capacity to refrigeration tons when required.
- Apply kW/ton and average load factor for average power.
- Multiply by runtime for electrical energy.
MechanicalIntermediateEnergy
Chiller Energy-Use Calculator
Calculate chiller electrical energy from cooling capacity, kW/ton, runtime, and load factor.
Why it matters: Chiller energy combines capacity, operating efficiency, load, and duration.
Calculated result
Engineering evaluation
Estimated chiller electrical energy (Eel)450,000 kWh
- Cooling capacity (Qton)
- 500 ton
- Average electrical input (Pavg)
- 225 kW
Engineering interpretation
Estimated chiller energy is 450000 kWh at average input 225 kW. The efficiency input remains kW/ton in both unit views.
Important limitations
- kW/ton varies with load, temperatures, flows, fouling, staging, and auxiliaries. Use interval data for detailed energy analysis.
Engineering knowledge center
Understand the calculation—not just the answer
Governing relationships
Qton = Q
Pavg = Qton·E·LF/100
Eel = Pavg·t
Current substitution
Qton = 500; Pavg = 500×0.6×75/100 = 225 kW; Eel = 450000 kWh.
Equation legend
Inputs and calculated quantities
- Q
- Cooling capacity — ton or kW
- E
- Operating efficiency — kW/ton
- t
- Runtime — h
- LF
- Average load factor — %
- Eel
- Estimated chiller electrical energy — kWh
- Qton
- Cooling capacity — ton
- Pavg
- Average electrical input — kW
Applications
How this calculation is used
Building design
Screen chiller energy at an operating profile.
Construction
Check power and capacity measurement boundaries.
Commissioning
Estimate period energy from representative capacity and kW/ton.
Quality controls
Assumptions and limitations
Assumptions
- Entered data describe one stable operating condition and use consistent measurement boundaries.
- Time, energy, and performance values are representative of the stated interval.
Limitations
- This is a preliminary evaluation and commissioning-support tool, not an automatic acceptance determination.
- Project sequences, manufacturer data, tariffs, codes, and professional review remain controlling.
Field use
Verification procedure
- Confirm the operating mode, test boundary, and instrument calibration.
- Collect simultaneous readings or a documented trend interval.
- Compare the result with the approved sequence, submittal, and project criteria.
Common engineering mistakes
- Combining measurements from different operating modes or time intervals.
- Ignoring sensor uncertainty, trend sampling, or the defined equipment boundary.
Technical basis
References and source standards
- U.S. Department of Energy—Better Buildings Solution CenterFederal HVAC energy-management and equipment-performance guidance.
- ASHRAE Handbook—HVAC Systems and EquipmentHVAC equipment, central-plant, air-system, and control-performance context; verify the licensed current edition during professional review.
- NIST Measurement and Calibration ResourcesFederal measurement, calibration, timing, and unit-system context.
Engineering calculation disclaimer
These engineering tools are provided for educational, preliminary evaluation, field verification, and commissioning support. Results depend on the accuracy of user-entered information and the assumptions stated for each calculation. Every colored status and comparison is a screening indicator only; project criteria, contract requirements, applicable codes, manufacturer instructions, measurement uncertainty, and authorized engineering judgment govern. The tools do not replace project-specific engineering analysis or the judgment of a licensed professional engineer.
Read the full use and limitation statement