Process Manufacturing worked example

Chilled Water Cost with chilled water load of 6 ton-hr / hr: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop chilled water load to 6 ton-hr / hr, then walk the calculation through step by step. Estimate chilled water or glycol cooling cost from use rate, runtime, and utility cost.

The inputs for this scenario

  • Chilled water load (ton-hr/hr): 6 ton-hr / hr (the input this scenario stresses; the baseline uses 12)
  • Cooling duration: 5 hr (held at the documented default)
  • Cost per ton-hour of cooling: 0.28 $ / ton-hr (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Cooling utility use = chilled water use rate × runtime.
  • Run cost works out to 8.4 $ at these inputs, and this is the headline figure for the scenario.
  • cooling utility used works out to 30 ton-hr at these inputs.
  • cooling runtime works out to 5 hr at these inputs.
  • cooling utility cost works out to 0.28 $ / ton-hr at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where chilled water load sits at 12 ton-hr / hr and the headline result is 16.8 $, this scenario comes in 50% below the baseline at 8.4 $.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to chilled water load, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It assumes a steady cooling load; chiller efficiency (kW/ton) drifts with condenser temperature and part-load, so use a seasonally representative $/ton-hr.

Results at a glance

  • Run cost: 8.4 $ (headline result)
  • cooling utility used: 30 ton-hr
  • cooling runtime: 5 hr
  • cooling utility cost: 0.28 $ / ton-hr

Run it with your numbers

  • To rerun this with your own numbers, open the live Chilled Water Cost calculator, set chilled water load to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.