In 1996, I worked at an environmental foundation on the coast of Maine that was an early adopter of compact fluorescent bulbs. At the time, they were expensive, and they flickered when you turned them on. After a long winter of getting flickered at every time I turned on the light, I started avoiding compact fluorescent bulbs.

Last week, one of my energy-zealot friends gave me a 1200 lumen compact fluorescent bulb after I commented on how quickly her CF lamp turned on.

I now have the 1200 lumen CF bulb in one of the overhead lights in my house. There is an identical lamp on the same circuit that still has an incandescent bulb rated at 1280 lumens. Both lamps have glass enclosures around them, so this is not the strongest argument, but neither my friend Aaron nor I can tell the difference between the two lamps– same brightness, same color, no flickering, and no buzzing. The CF does seem slightly dimmer for the first 30 seconds after a cold start, and I have been able to hear buzzing when the CF bulb is in an open socket less than six inches from my ear. These are the most minor of objections– overall, my previous opposition to CF bulbs is now gone.

Now that I work at a renewable energy engineering company, I’ve been looking at the options more closely. Below the costs compared for the bulbs I have in my house. Compact fluorescent is the clear winner. In my calculations below, I assume electricity costs of $0.20/kWh, which is what I pay in Massachusetts, but CF’s now beat incandescent even with free electricity.

Incandescent (GE Reveal 100, #48690)
Cost for bulb: 1280 lumens, $1.25 ea. in qty. 4, 750 hours, 100 W: $0.014/lumen-year
Cost for power: (0.100 kW * 24 hours * 365.25 days * $0.20/kWh / 1280 lumens ) = $0.137/lumen-year
Total cost: $0.151/lumen-year

Compact fluorescent (Maxlite Micromax Spiral MLM20S)
Cost for bulb: 1200 lumens, ~$6 ea. in qty. 1, 10000 hours, 20 W: $0.004/lumen-year
Cost for power: (0.020 kW * 24 hours * 365.25 days * $0.20/kWh / 1200 lumens ) = $0.029/lumen-year
Total cost: $0.033/lumen-year

Out of curiosity, I decided to compare a halogen bulb from the drugstore down the street and an LED bulb I found on the global netweb to the bulbs I have. The LED bulb is almost competitive with the CF on cost, but it only produces 60 lumens, so you’d need 20 of them to light a room, which would cost $500. They would last for eternity, but I think I’ll wait a few years for the cost to drop before I buy those.

Halogen
Cost for bulb: 830 lumens, $7 ea. in qty. 1, 2000 hours, 50 W: $0.037/lumen-year
Cost for power: (0.050 kW * 24 hours * 365.25 days * $0.20/kWh / 830 lumens ) = $0.106/lumen-year
Total cost: $0.143/lumen-year

LED (CC Vivid Plus)
Cost for bulb: 60 lumens, $25 in qty. 1 (on sale, even!), 60000 hours, 1.3 W: $0.061/lumen-year
Cost for power: (0.0013 kw * 24 hours * 365.25 days * $0.20/kWh / 60 lumens ) = $0.038/lumen-year
Total cost: $0.099/lumen-year