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Plant Engineering Calculator

Updated Sep 18, 2026

Chiller Setpoint Savings Calculator — Leaving Water Reset & Annual kWh

Estimate annual chiller savings from a chilled-water setpoint reset using measured baseline kW and an entered percent-power improvement per degree of reset.

Live calculationWorking shownPrivate in browser

Inputs

Results

Estimated power saved 4.50 kW
Estimated new power 295.50 kW
Annual energy saved 22500 kWh
Annual cost saved $2250
More actions

Shared links reopen these inputs. Recent and saved calculations stay in this browser unless you clear site data.

Formula

saved kW=baseline kW×reset degrees×saving factor; annual kWh=saved kW×hours.

Your calculation, step by step

These steps use the values currently entered above so the result can be checked independently.

  1. 1.Validated local response = 1.000 °C × 1.500%/°C ÷ 100 = 0.01500.
  2. 2.Chiller power saved = 300.00 × 0.01500 = 4.500 kW; screened new chiller power = 295.500 kW.
  3. 3.Annual chiller energy saved = 4.500 × 5000 = 22500.0 kWh.
  4. 4.Annual chiller-only value = 22500.0 × $0.1000 = $2250.00; pump/coil/humidity effects are outside this arithmetic.

How to use this calculator

  1. Enter measured or design values using the units shown beside each field.
  2. Review the live results and the substituted calculation steps before using the estimate.
  3. Check the assumptions below, then continue to a related calculator when the next engineering decision needs another model.

Worked example

A 300 kW chiller with a validated 1.5%/°C response and a 1°C reset screens at 4.5 kW savings.

Assumptions and limits

  • The saving factor is plant-specific and should be derived from trend data or OEM performance maps.
  • Check humidity, coil authority, process loads, pumping and comfort before resetting temperature.
  • In variable-flow systems, higher chilled-water temperature can increase flow/pump energy or degrade ΔT, so evaluate net plant energy.

How to interpret the result

Treat the primary result as an engineering screening value, then use the secondary outputs to understand scale, energy or operating impact. Confirm site measurements, equipment limits and applicable standards before making a design or control change.

Questions engineers ask

Does raising chilled-water supply temperature always save plant energy?

No. ASHRAE notes that reset can reduce chiller lift but may increase coil flow and pump energy, degrade ΔT or conflict with humidity/process requirements. The net plant result depends on system design and load.

Where should the percent-power-per-degree response come from?

Prefer measured trend data or OEM performance maps over a generic constant. The linear factor is a local screening approximation and should not be extrapolated until it predicts implausible or negative chiller power.

How should a reset strategy protect critical loads?

Use the most demanding zone/process valve, humidity requirement or other supervisory signal to limit reset. Hospitals, data centers, museums and process cooling can have tighter requirements than ordinary comfort systems.

Continue the calculation

Use the next calculator in the same engineering workflow instead of restarting from search.

chiller kw per tonchiller plant efficiencychiller delta t
Methodology. MAXScanner shows the governing formula, entered values and calculation outputs so the estimate is auditable. The calculator is a screening aid; assumptions and equipment-specific limits remain part of the engineering review.