Energy & Sustainability worked example

Lighting Retrofit Payback with installed lighting retrofit cost of 32,000 $: a worked example

Suppose installed lighting retrofit cost falls to 32,000 $. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate simple payback for a lighting retrofit from project cost, annual electricity savings, and support cost.

The inputs for this scenario

  • Installed lighting retrofit cost: 32,000 $ (the input this scenario stresses; the baseline uses 64,000)
  • Annual lighting energy and maintenance savings: 24,500 $ / yr (held at the documented default)
  • Annual controls or maintenance support cost: 1,200 $ / yr (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Net annual lighting savings = annual lighting energy and maintenance savings - annual controls or maintenance support cost.
  • Lighting retrofit simple payback works out to 1.37 yr at these inputs, and this is the headline figure for the scenario.
  • Net annual lighting savings works out to 23,300 $ / yr at these inputs.
  • Installed lighting retrofit cost works out to 32,000 $ at these inputs.
  • Five-year lighting net value works out to 84,500 $ at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where installed lighting retrofit cost sits at 64,000 $ and the headline result is 2.75 yr, this scenario comes in 50% below the baseline at 1.37 yr.
  • It computes simple payback in years by dividing installed retrofit cost by net annual savings (gross lighting savings minus ongoing support cost). When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Lighting retrofit simple payback: 1.37 yr (headline result)
  • Net annual lighting savings: 23,300 $ / yr
  • Installed lighting retrofit cost: 32,000 $
  • Five-year lighting net value: 84,500 $

Run it with your numbers

  • To rerun this with your own numbers, open the live Lighting Retrofit Payback calculator, set installed lighting retrofit cost to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.