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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 or suggested.
This calculator gives payback time, and both the annual and life-time 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, can compare any lighting.

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.  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.   

  Set up basic parameters for energy statistics:
  ANSI/ASHRAE/IESNA Standard 90.1-2007
Lighting Power Density Section
   Original (HID) Fixture Wattage + Ballast  Watts LPD = Total Watts ÷ Total Square Feet  
    LED Wattage   Watts  Sq-Ft per Fixture  =  Label Total 
=  Saved per Fixture  Label Watts  Enter Target LED LPD
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)
×  Fixture Quantity  LabelThis LPD combo allows Label LED fixtures.
=  Power Saved     Label W  =  Label kW Label
LPD Statistics      W/Ft 2 
Original LPD     Label 
  LED LPD     Label 
=  Saved     Label 
 ×  Daily use  Hours  Label
×  Weekly use   Days
×  Yearly use   Weeks
  =  Annual Energy Savings    Label  kWhr
LPD Notes:
• Target LPD uses LED Watts and Quantity, and affects only the count below it.
• HID LPD = LED projection when = Watts.
×  Power Cost  $  per kWhr
=  Annual Energy Cost Savings    $Label  
    Investment: Label  
  Cost for 1 LED Fixture, Fully Installed =
( 'Per-Fixture' costs and discounts here. ) 
$ May be direct cost if retrofit, or difference between LED and the
fixture it substitutes if a new installation. Include all costs & labor.
$Label × Label  fixtures  = $Label  + FIXED JOB COSTS $   = $Label  Label Investment
Subtract a rebate from JOB COSTS, or, enter negative (-)JOB COSTS if rebate only.
    Energy cost savings and reduced CO2 production during LED lifetime:  
  LED Life   Hours   
÷ Hours of use per year  Label  Hrs/Year
CO2 reductions *
Label Tons Less per year
Label Tons Less per lifetime
=  LED Operational Lifetime  Label  Years
×  Annual Savings  $Label 
=  Lifetime Energy Cost Savings  $Label 
    Maintenance savings during LED lifetime:  
  LED Life    Label  Hours   
÷ Original fixture life   Hours 
×  Number of fixtures  Label  
×  Fully burdened repair cost of original fixture.  $  Group relamping, ballasts and photocells.
 Include labor, fuel, travel, equipment, inventory, etc.
=  Lifetime Maintenance Savings  $Label  
    Payback time and ROI based on amortized changeout cost savings per year:  
  Lifetime Maintenance Savings  $Label    
÷  LED Lifetime  Label  Years 
=  Amortized Maintenance Savings  $Label Per Year 
  Label  Payback 
Investment ÷ Energy Savings  $Label ÷ $Label   =  Label Years on energy alone
Investment ÷ (Energy + Maint. Savings)  $Label ÷ $Label   =  Label Years on energy & maint.
 Simple ROI (Payback Investment) ÷ Investment     =  Label  %  ROI
 *US national average CO2 emissions caused by various power generation capabilities, value provided by the US EPA. 

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