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Thursday, April 8, 2010

Switching to Greener LEDs - Watching the Watchers

Switching to Greener LEDs - Watching the Watchers

Most of us have heard suggestions or exhortations that we should replace our old-fashioned incandescent light bulbs (first developed 130 years ago by Thomas Edison) with more energy-efficient compact fluorescent lamps. The difference in efficiency is significant; a typical incandescent bulb produces about 13-15 lumens of visible light for every watt of electricity consumed. Most of the bulb's output is in the form of heat. A compact fluorescent lamp [CFL], in comparison, produces about 45-70 lumens per watt, depending on the design. Despite the efficiency advantage, though, CFLs are not an ideal solution, for several reasons:

  • Although their potential lifetime is an order of magnitude better than comparable incandescent lamps, it can be severely curtailed if the lamp is switched on and off frequently.
  • Some older lamp designs have flicker in the light output at a frequency of about 100-120 Hz (twice the AC line frequency). Although this is not perceptible, and does not affect most people, there is some evidence that it can have an adverse effect on some sensitive people.
  • Fluorescent lamps contain mercury, which is a potent neurotoxin. Used lamps must be disposed of properly, and special precautions are recommended if a lamp is broken. (For example, a vacuum cleaner should not be used to clean up the mess, because it can aerosolize a mixture of phosphor and mercury.)
  • Fluorescent lamps cannot be used with conventional light dimmers.


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