CFLs Aren't Perfect

Thank you for your recent article on light bulb bans [see


Vol. 16, No. 4]. It was well documented and had good points about the value of improving incandescent lamps rather than banning them. Incandescent lamps still have their place in some situations, and it would make no sense to replace every incandescent bulb with a compact fluorescent lamp (CFL), since CFLs don’t like to be switched on and off. If CFLs don’t get three to five hours of operation at a time, they will burn out within a year, causing customers to doubt their energy-saving potential. In addition, we have to specially dispose of the lamps, and they require more energy to produce than incandescent lamps.

You have the ability to draw the attention of the public, manufacturers, and sales companies and should educate the public on the correct use and disposal of CFLs and on which situations are appropriate for the use of CFLs.

Stefan Bernath, Energy Coordinator

Alberta Infrastructure

and Transportation

Edmonton, Alberta, Canada

Editors’ response:Indeed, Mr. Bernath is correct that switching CFLs on and off does shorten lamp life, but his conclusion that they need a three- to five-hour on-cycle to maintain a reasonably long life does not appear to be correct. Robert Clear, a staff scientist at Lawrence Berkeley National Laboratory, told

EBN that it has been difficult to get data on this question, but a 1998 study of electronically ballasted CFLs found a 20% reduction in lamp life if the on-time was reduced to one hour. With significantly shorter on-times, the lamp life is dramatically reduced: with 15-minute on-time cycling, lamp life dropped 70% and with five-minute on-time lamp life dropped 85% (which brings the lamp life close to that of incandescent light bulbs). “This suggests that you should consider replacing incandescents with CFLs in any application where the lamp is on an average of [at least] about 10 minutes per start,” said Clear. He added that “every switch cycle is equivalent to about 6 minutes of lamp life. This means that you should turn a CFL off if you think it won’t be turned on again for another five minutes or so.” This approach should also maximize electricity and cost savings. We strongly agree with Mr. Bernath’s point about the need for safe disposal of CFLs due to the mercury content.

Published August 2, 2007

Stefan, B. (2007, August 2). CFLs Aren't Perfect. Retrieved from https://www.buildinggreen.com/op-ed/cfls-arent-perfect

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August 2, 2007 - 12:01 pm

Didn't Myth Busters test this as well? Actually I think they tested the 'on' surge of power used, not lamp life and embodied energy. Good episode, nonetheless.