Skip to main content

Plant Engineering Calculator

Cooling Tower Fan Power Savings Calculator — Speed, Fan Laws & Annual kWh

Estimate cooling-tower fan power at reduced speed using the cube law, then calculate kW, annual kWh and cost savings against measured baseline power.

Inputs

Results

Speed ratio 0.800
Ideal cube-law power 15.36 kW
Power incl. drive/control loss 15.82 kW
Power saved 14.18 kW (47.3%)
Annual energy saved 85075 kWh
Annual cost saved $8508
Simple payback 1.41 years

Formula

P2=P1×(N2/N1)^3; saved=P1−P2.

Worked example

Reducing a 30 kW fan from 100% to 80% speed screens at about 15.36 kW under the ideal cube law.

Assumptions & limits

  • Fan laws apply to dynamically similar operation; actual VFD, motor and system efficiencies vary.
  • Tower thermal performance and approach constraints determine whether reduced speed is feasible.

FAQs

What does this Cooling Tower Fan Power Savings Calculator calculate?

Estimate cooling-tower fan power at reduced speed using the cube law, then calculate kW, annual kWh and cost savings against measured baseline power.

Can I use the result for final equipment selection?

Use it as a transparent engineering and energy-screening result. Verify final decisions with measured site data, OEM curves, applicable standards and operating limits.

Why does MAXScanner show assumptions?

Plant calculations can look exact while depending heavily on operating assumptions. Showing them makes scenarios auditable and easier to compare.

Related calculators

cooling tower fan specific powerfan affinity lawscooling tower range approach

Last updated: 17 September 2026