Fan Energy Saving Calculator
Estimate energy and cost savings when a fan is speed-controlled with a VFD/inverter. This calculator assumes fan power follows the cube law: power ∝ speed³.
Selected Speed Summary
Power at 100% speed
2.20 kW
Power at selected speed
1.13 kW
Energy saved
48.8%
Money saved per hour
£0.27
| Period | Cost at 100% | Cost at Selected Speed | Saving |
|---|---|---|---|
| 1 Hour | £0.55 | £0.28 | £0.27 |
| 8 Hours | £4.40 | £2.25 | £2.15 |
| 12 Hours | £6.60 | £3.38 | £3.22 |
| 1 Day | £13.20 | £6.76 | £6.44 |
| 1 Week | £22.00 | £11.26 | £10.74 |
| 1 Month | £95.26 | £48.77 | £46.49 |
| 1 Year | £1144.00 | £585.73 | £558.27 |
Assumption: this calculator is intended for centrifugal or axial fans controlled properly by a VFD/inverter.
Real-world results vary with motor efficiency, system resistance, operating point, and control method.
Quick Comparison Table
| Fan Speed | Approx. Power Draw | Energy Reduction vs 100% | Cost per Hour | Saving per Hour |
|---|---|---|---|---|
| 100% | 2.20 kW | 0.0% | £0.55 | £0.00 |
| 90% | 1.60 kW | 27.1% | £0.40 | £0.15 |
| 80% | 1.13 kW | 48.8% | £0.28 | £0.27 |
| 70% | 0.75 kW | 65.7% | £0.19 | £0.36 |
| 60% | 0.48 kW | 78.4% | £0.12 | £0.43 |
| 50% | 0.28 kW | 87.5% | £0.07 | £0.48 |
| 40% | 0.14 kW | 93.6% | £0.04 | £0.51 |
| 30% | 0.06 kW | 97.3% | £0.01 | £0.54 |