Plant Utilities worked example

Chiller Load at 7.2% startup and fouling allowance: a worked example

This worked example runs the chiller load numbers for a tougher week than the baseline: 7.2% startup and fouling allowance instead of the typical 10%. Estimate chiller load coverage time for process cooling or chilled water support, including startup and fouling allowance.

The inputs for this scenario

  • Required chilled-water load duty: 360 chiller-min (held at the documented default)
  • Chiller cooling-rate coverage: 1 chiller-min / min (held at the documented default)
  • Startup and fouling allowance: 7.2 % (the input this scenario stresses; the baseline uses 10)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base chiller load time = required chilled water load time รท chiller load coverage rate.
  • Required chiller load time works out to 386 min at these inputs, and this is the headline figure for the scenario.
  • Base chiller load time works out to 360 min at these inputs.
  • Allowance applied works out to 7.2 % at these inputs.
  • Utility coverage rate works out to 1 chiller-min / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where startup and fouling allowance sits at 10% and the headline result is 396 min, this scenario comes in 2.55% below the baseline at 386 min.
  • Use it when scheduling chiller run time for a cooling window or estimating operating hours for a known chilled-water duty. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Required chiller load time: 386 min (headline result)
  • Base chiller load time: 360 min
  • Allowance applied: 7.2 %
  • Utility coverage rate: 1 chiller-min / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Chiller Load calculator, set startup and fouling allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.