A Tool to Calculate Payback of LED Lighting with costs & interest
Please read: 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. Check the DOE for your requirement.
Non-residential electric usually has additional cost for less than 90% Power Factor.
This calculator will not perform properly if removed from this site. Click here for: Parking Lot LightingParking Garage Lighting
Start = select entry with mouse, use Tab key to enter and step.
Step back with Shift Tab.
If residential lighting, enter >= 95 for PF (Power Factor).
Parameters for energy statistics:
Lighting Power Density Section
Enter Power Consumption, Original Power Factor, & No. of Fixtures
LPD = Total Watts ÷ Total Square Feet
Orig. W
& PF%
LED W
Quantity
Sq-Ft per Fixture = Total
Totals: W
W
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)
× Daily use
Hours
This LPD combo allows LED fixtures.
× Weekly use
Days
LPD Statistics W/Ft 2
Original LPD
– LED LPD
= Saved
× Yearly use
Weeks
× Power Cost
$
/ kWhr
Annual Energy Cost:
Original $
LED $
LPD Notes: • Target LPD uses LED Watts × Quantity, and affects only that count below.
• HID LPD = LED projection when = Watts.
Savings:
Annual = $ Monthly = $
LED Investment:
(LED maintenance is cleaning, inspection, etc. as should be done with all lighting.)
Full Cost for 1 Fixture Installed. ( costs - discounts ) =
$
LED Maintenance Interval: Years
@ $
per Visit.
[ Lifetime ÷ Interval × Cost × Quan.= $ ]
( $ ×) + $ = $
+FIXED JOB COSTS $
= $
Investment
Subtract a rebate from FIXED JOB COSTS, or, enter negative (-)JOB COSTS if rebate only.
LED energy costs and reduced CO2 production during LED lifetime:
LED Life Hours ÷
Hours/Year =Years Lifetime
CO2 reductions (based on Coal fuel)
Tons Less / year
Tons Less / lifetime
Years × $ annual energy cost = $
Years × $ annual energy savings
= $ (over original)
$ invest. + $ energy = $ Project Cost
Original fixture with lifetime maintenance and energy costs:
Original fixture life Hours ÷ Hours/Year
= Years Lifetime
$ Full Cost for 1 Fixture Installed
Years
× $ annual energy cost = $
Relamp Cost $ (relamping, cleaning, etc. every years)
$ Fixtures & Maint. + $ energy = $ Orig. Cost during LED Lifetime, repaired times.
Payback time and ROI with Amortized Cost + Interest:
