This past semester, I wrote a paper on the cost comparison between incandescent, LED, and compact fluoresent (CFL) lightbulbs. Here's the result, and then I'll 'splain it:
All bulbs compared were higher-quality units, so that we weren't comparing ultra-cheap items to expensive ones. All costs are also modified to allow for 3% annual inflation.
- Replacement costs were based on the bulbs needed to produce 750 lumens for 6 hours per day, factored for the lifespan (in hours) for each bulb, and projected over 20 years.
- Disposal costs were calculated by taking the total bulbs needed over 20 years, and for incandescent and LED bulbs, projecting standard waste disposal costs for normal trash. For CFL disposal, I factored in a proposed $0.50 per bulb disposal fee.
- Electrical costs were based on producing 750 lumens for 6 hours per day, at $0.08 per KWH (Nebraska costs). Depending on where you live, the electrical costs would be significantly higher.
As you can see from the chart, over twenty years, CFL bulbs are cheapest to operate, even if the cost per CFL bulb stays relatively flat.