Energy & Sustainability worked example

Lighting Retrofit Payback with installed lighting retrofit cost of 160,000 $: a worked example

Push installed lighting retrofit cost up to 160,000 $ and the picture changes. This example computes every intermediate figure at that operating point. a facilities manager needs to screen a lighting efficiency project

The inputs for this scenario

  • Installed lighting retrofit cost: 160,000 $ (raised for this scenario; the documented default is 64,000)
  • Annual lighting energy and maintenance savings: 24,500 $ / yr (unchanged)
  • Annual controls or maintenance support cost: 1,200 $ / yr (unchanged)

Working through the calculation

  • Applying the documented formula (Net annual lighting savings = annual lighting energy and maintenance savings - annual controls or maintenance support cost) to the inputs above produces each figure below.
  • At this operating point the engine returns 6.87 yr for lighting retrofit simple payback, the number this scenario is built around.
  • At this operating point the engine returns 23,300 $ / yr for net annual lighting savings.
  • At this operating point the engine returns 160,000 $ for installed lighting retrofit cost.
  • At this operating point the engine returns -43,500 $ for five-year lighting net value.

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 150% above the baseline at 6.87 yr.
  • It computes simple payback in years by dividing installed retrofit cost by net annual savings (gross lighting savings minus ongoing support cost). The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Lighting retrofit simple payback: 6.87 yr (headline result)
  • Net annual lighting savings: 23,300 $ / yr
  • Installed lighting retrofit cost: 160,000 $
  • Five-year lighting net value: -43,500 $

Run it with your numbers

  • Every input above is editable in the live Lighting Retrofit Payback calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.