ClueLuma

Installed cost and simple payback (SPP) calculator

Simple payback uses installed cost divided by net yearly savings.

SPP=N×CretrofitSnet\mathrm{SPP} = \frac{N \times C_{\text{retrofit}}}{S_{\text{net}}}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

fixture
$/fixture
$/yr
yr

Worked example

Given

  • NN = 300 fixture
  • CretrofitC_{\text{retrofit}} = 150 $/fixture
  • SnetS_{\text{net}} = 9,000 $/yr
SPP=300×1509000=5\mathrm{SPP} = \frac{300 \times 150}{9000} = 5

Symbols and units

SymbolMeaningUnit
SPP\mathrm{SPP}simple payback periodyr
NNretrofitted fixturesfixture
CretrofitC_{\text{retrofit}}installed cost per fixture$/fixture
SnetS_{\text{net}}annual net savings$/yr

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Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.