Led Relamping Payback
Calculator
Results
- Break-even (years)
- 0.268249 yr
- Net position at the horizon
- $7,463.72
- Total savings
- $7,643.72
- First-year saving
- $671.02
- Energy saved per year (kWh)
- 2,277.6 kwh
- Net upfront cost
- $180.00
Cumulative cash flow crossing zero at break-even
- Cumulative cash flow
- Cumulative cost of doing nothing
- Cumulative cost with the upgrade
Year-by-year cash flow until break-even
| 1 | 671.02 | 671.02 | 491.02 | 779.64 | 288.62 |
| 2 | 690.15 | 1,361.16 | 1,181.16 | 1,581.36 | 400.19 |
| 3 | 709.85 | 2,071.02 | 1,891.02 | 2,405.81 | 514.79 |
| 4 | 730.15 | 2,801.17 | 2,621.17 | 3,253.68 | 632.51 |
| 5 | 751.06 | 3,552.22 | 3,372.22 | 4,125.67 | 753.45 |
| 6 | 772.59 | 4,324.81 | 4,144.81 | 5,022.51 | 877.70 |
| 7 | 794.77 | 5,119.58 | 4,939.58 | 5,944.95 | 1,005.36 |
| 8 | 817.61 | 5,937.20 | 5,757.20 | 6,893.74 | 1,136.54 |
| 9 | 841.14 | 6,778.34 | 6,598.34 | 7,869.68 | 1,271.34 |
| 10 | 865.38 | 7,643.72 | 7,463.72 | 8,873.58 | 1,409.86 |
Comparison
| Scenario | Total cost over the horizon | Cumulative energy cost | Net position at the horizon |
|---|---|---|---|
| Do nothing | 8,873.58 | 8,873.58 | 0.00 |
| With the upgrade | 1,409.86 | 1,409.86 | 7,463.72 |
Formula
saving(n) = N × (W_old − W_led)/1000 × h × price × (1+g)^(n−1) + Δlamp replacement= 0.27
Note
This is a simplified cash-flow model. It projects the prices, escalation rate and equipment costs you entered with a single geometric escalation and no discounting, no inflation adjustment, no financing costs and no tax treatment; savings are assumed to accrue evenly within each year, which is what the fractional break-even interpolates. Real energy prices, tariff structures, grants, weather, occupancy and equipment performance vary widely and change over time. A break-even of zero means the cumulative cash flow never crosses into positive territory within the horizon you chose. Get a professional energy assessment and a written quotation before committing to any of these measures.
More in Energy payback
See all →Frequently asked questions
How is the payback period calculated for an LED relamping project?+
The calculator divides the total cost of the new LED fixtures or bulbs (minus any rebate) by the annual dollar savings from lower wattage and reduced replacement frequency. The annual savings come from the wattage difference multiplied by daily run hours, days per year, and your electricity rate. It's a simple payback, not accounting for the time value of money unless stated.
Why do run hours matter more than the wattage difference alone?+
A fixture that saves 40 watts but only runs 2 hours a day saves far less energy per year than one saving 20 watts but running 16 hours a day. Run hours is the multiplier that turns a wattage delta into actual kilowatt-hours, so an inaccurate estimate of daily usage is the fastest way to get a misleading payback.
Should I include the cost of disposing of old fluorescent tubes and ballasts?+
Yes if you're removing linear fluorescents, since many jurisdictions require special disposal for tubes containing mercury and ballasts can contain PCBs in older units, and that fee is a real upfront cost. Leaving it out understates the investment and makes the payback look shorter than it will actually be.
Does the calculator factor in the extra savings from not replacing bulbs as often?+
A complete model should include avoided relamping labor and bulb costs, since LEDs typically last 25,000-50,000 hours versus 1,000-15,000 for incandescent or fluorescent lamps. If your version of the calculator only compares energy costs, your real payback is actually shorter than shown because you're also avoiding several future replacement cycles.
Why might commercial or high-use spaces see payback in under a year while a home doesn't?+
Payback speed is driven almost entirely by run hours: a warehouse or retail space with lights on 12-16 hours a day accumulates savings far faster than a bedroom light used 1-2 hours a day. The same wattage reduction and same bulb price can produce paybacks that differ by a factor of 10 depending purely on how many hours the fixture operates.