LED vs incandescent bulbs: payback in months, with the arithmetic
Lighting is a classic case where a small up-front cost beats a larger running cost. The numbers are easy to check.
Yearly running cost
| Incandescent (60 W) | LED (9 W) | |
|---|---|---|
| kWh per year | 0.06 x 3 x 365 = 65.7 | 0.009 x 3 x 365 = 9.9 |
| Cost per year | about $11.17 | about $1.68 |
| Saving per year | about $9.49 |
If the LED costs $3 more than the old bulb, it pays back in about 4 months at this usage. Bulbs are also rated for different lifetimes, which adds to the savings because you buy fewer replacements.
What to check on the package
- Lumens, which measure brightness, rather than watts
- Colour temperature in kelvin, since warm and cool light feel different
- Whether the bulb is dimmable if you use a dimmer
- The rated lifetime and warranty
Where it matters most
Bulbs that are on for many hours a day, such as in kitchens and living rooms, repay fastest. Rarely used closets and attics have the longest payback.