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Street Lighting Equipment Corporation
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Universal ROI Calculator


An Estimating Tool to Compare
Payback of LED Lighting
Please read:
Light levels are NOT calculated here.  ENSURE THAT REPLACEMENT HAS EQUIVALENT LIGHTING PERFORMANCE.
This calculator gives payback time, and both the annual and life-time cost & savings figures for energy, maintenance, and CO2 production.  It calculates Lighting Power Density from area of at least 50 square feet per fixture, and provides the maximum fixtures allowed from a target LPD.  It's not exclusive to LED, and can compare any lighting.
The calculator will not perform properly if copied to a computer.  Updates and maintenance are done from the web site.

Simple ROI is calculated on product lifetime with the industry standard  [ (Payback – Investment) ÷ Investment ×100 ] formula.  Cost may be full direct if retrofit, or may be difference (Original - New) if complete new installation.   Interest is on the the Investment, and is deducted from the annual savings used to repay that amount.   Include ALL COSTs and verify calculations before implementing a solution.  Check with your electric utility provider for rate structures related to Lighting Power Density (LPD/UPD).  Site owner not responsible for errors, misapplications or oversights.
Start with the Tab key, or select an entry with mouse.   Step forward with Tab; fill in shaded cells as required.  Step back with Shift Tab.
  Parameters for energy statistics:
  Enter Power Consumption Label &  No. of Fixtures  
Original Watts LED  Watts Quantity Label
Total Label kW Total Label kW
Hour-Day-Week Notes:
• For Occ. sensors or dimming,
   use average hours
• For photocell use nighttime hours
• Use decimal weeks if holidays
   affect lighting (1 day = 0.14 wk)
×  Hours   ×  Days   ×  Weeks  Label
× $  Power Cost / kWhr
Annual Costs:   Original  $Label    LED  $Label
Annual Savings  =  $Label
  Original fixture lifetime maintenance and energy costs:
    Original fixture life  Hours   ÷  Label Hours/Year  = Label Years Lifetime  
Years ×  $Label annual energy cost   =   $Label Repair/Replacement Cost 
$ × Label = $Label
 $Label Fixtures & Maint. + $Label energy
= $Label  Orig. Cost in LED Lifetime, replaced Label times.
      Environmental:
  LED Investment: Label  
  Full Cost for 1 Fixture Installed.  ( costs - discounts )  $ % LabelLabel  
Maintenance Interval:  Years @ $  per visit.  [ Lifetime ÷ Interval × Cost × Quan.= $Label ]
( $Label × Label ) + $Label = $Label  Subtract a rebate from JOB COSTS, or
enter negative (-)JOB COSTS if rebate only.
+ FIXED JOB COSTS $ = $Label   Investment Label
    LED energy costs and savings during LED lifetime:     Label  
    LED Life  Hours   ÷   Label Hours/Year  = Label Years Lifetime  
Years ×  $Label annual energy cost    =  $Label
Years ×  $Label annual energy savings  =  $Label  (over original)
 $Label investment +  $Label energy  =  $Label  Project Cost
 Payback & ROI with Amortized Cost + Interest:Label
  LED Investment ÷ Energy Savings  $Label ÷ $Label   =  LabelLabel Years energy alone  
Investment ÷ ( Energy + Maint. Savings ) $Label ÷ $Label   =  LabelLabel Years energy & maint.
 Simple ROI ( Payback – Investment ) ÷ Investment    =  LabelLabel % ROI from energy savings
 
  Lighting Power Density = Watts ÷ Square Feet
Target W/Ft 2   Allows Label LED fixtures		  Sq-Ft per Fixture
=  Label Total
LPD Statistics   W/Sq-Ft
Original LPD   Label 
–  LED LPD   Label 
=  Saved   Label 
CO2 reductions *
Label Tons Less per year
Label Tons Less per lifetime
  Restore Default Values  
Label
 
*US national average CO2 emissions caused by various power generation capabilities, value provided by the US EPA.
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