This calculator gives payback time, the annual and life-time energy AND maintenance savings when you upgrade your lighting to LEDs.
Enter the wattage and life for both the old and new fixture and the billing rate per kilowatt-hour.
Be sure to include all costs, i.e. labor, parts, inventory, etc.
Start with Tab key, fill in the shaded cells and/or step forward with Tab key. (Shift Tab to step backward.)
1. Compute the total power (kilowatts, kW) saved by upgrading conventional lighting technology to LED technology.
Original Fixture Wattage + Ballast
LED Wattage
Watts Saved per Fixture
# of Fixtures to Replace
Power Saved
W
-
W
=
W
×
=
Label W
Label kW
2. Compute the total energy (kilowatt hours, kWh) saved annually.
Total Kilowatts Saved
Hours of Use per Day
Days of Use per Week
Weeks of Use per Year
Total kWh Saved per Year
Label kW
×
×
×
=
Label
3. Compute the total energy cost savings per year.
Total kWh Saved per Year
Your Energy Cost per kWh (typ. $0.10)
Energy Cost Savings per Year
Label kWh/yr
×
$
=
$Label
4. Compute energy cost savings over the life of the LED.
Replacement LED Life (hours)
Hours per Year Usage
LED Est. Life
Energy Cost Savings per Year
Lifetime Energy Cost Savings
Hr
÷
Label hr/yr
=
Label Years
×
$Label
=
$Label
5. Compute payback from energy cost savings.
NOTE: "LED cost" is the amount amortized in payback calculations. It should include installation costs.
It should be the difference between LED and the fixture it replaces (new installation). Or, it may be the direct cost (retrofit).
Payback From Energy Savings
=
LED Cost, or, Difference between LED & Original
=
$× Label Units
=
Label Years
Energy Cost Savings per Year
$Label
Return on Investment (ROI)
Based upon 100% = repayment in year #1
=
100
=
100
=
Label%
Simple Payback
Label
6. Compute maintenance savings over the life of the LED. Include labor, equipment, fuel, parts, inventory, etc.
LED Life (hours)
Original Fixture Life (hours)
# of Fixtures
Maintenance Labor Original Fixture
Maintenance Parts Original Fixture
Lifetime Savings in Maintenance
Label
÷
×
Label
×
( $
+
$ )
=
$Label
7. Compute the amortized changeout cost savings per year.
Total Lifetime Replacement Cost Savings
Lifetime of Replacement Fixture
Total Amortized Savings per Year
$Label
÷
Label Years
=
$Label
Simple Payback on Energy Consumption And Maintenance Costs
