Thursday, January 25, 2007

How many environmentalists does it take to change a light bulb?

Answer, only one, but it takes her six hours to research all the consequences

Maybe I exaggerate, but this decision sure seemed complex. We needed to change the ceiling light in our kitchen. The original fixture was probably installed when the house was built in 1976. It featured 8, 40 watt bulbs. We probably would have kept the fixture, but one of the sockets went bad, so we were left with seven good bulbs and one burnt-out one.

We have all been learning that we should be replacing our incandescent light bulbs with compact fluorescents (CFL), which screw into regular light sockets and cost 70% less energy. Even Walmart has gotten on the band-wagon. It wants to persuade every household to buy at least one CFL. There’s no question that this campaign could have an enormously positive impact. General Electric, which built its business on the old incandescent bulbs, is participating in the revolution. "The real issue is, if we don't do it, someone else will," says GE's ecomagination vice president, Lorraine Bolsinger, of Wal-Mart's effort to push CFLs. "It's old thinking to imagine that you can hold on to a business model and outsmart the consumer. You can't." It is good to see evidence that some businesses are capable of abandoning the zero sum thinking that General Motors used to kill its electric cars.

My decision to install a new ceiling fixture should have been a simple one. However, I learned along the way that compact fluorescents are not designed to work with dimmer switches. I had installed a dimmer switch on the light earlier as an energy-saving measure, so I would have to remove that.

The second task was to find a fixture large enough to cover the space taken by the previous fixture, a square flush-mounted model. This is where a lot of the woman-hours were expended, mostly because we had a 14” square fixture that needed to be covered by a 20” diameter ceiling light. A lot of the energy-efficient ceiling models use circline bulbs, round fluorescent bulbs, and this is the kind of light I purchased. These bulbs are very efficient, and are now designed to put out a softer, higher quality light. My circline bulb is supposed to last 6 years, or 15,000 hours. The negative side of fluorescent and compact fluorescent lights is that they contain mercury. Therefore, when they burn out, they must be disposed of according to the instructions from your local hazardous waste authority.

A surprising number of fixtures are designed specifically to work with halogen bulbs. These bulbs are 10-20% more efficient than incandescent bulbs, and they may last longer. Halogens burn hotter than incandescents, so they must be enclosed in a suitable housing.

LED lights (light-emitting diodes) are not suitable for ceiling lights, but they are the most energy efficient lighting method. They have a very long life span, some up to 100,000 hours. Tree huggers who like Christmas lights should be purchasing LED lights.

Wikipedia has a great site where you can compare the efficiency of incandescent lights to CFL’s. Here is my assessment of the cost and environmental savings of the new ceiling fixture over the first 3000 hours of service:

Old light fixture: electricity cost of 320 watts (800 hours/year @ $.08 per KWh): $76.80 plus cost of replacing 8 bulbs twice, $27.04, for a total cost of $103.84. Total Kwh usage:256 Kwh. We generate 1.55 pounds of CO2 per Kwh, so I would generate 396.8 pounds of CO2.

New light fixture: electricity cost of 72 watts (800 hours/year): $17.28, plus cost of two circline bulbs: $20.04, for a total cost of $37.32. Total Kwh usage: 57.6. Using the same estimate, I generate 89.28 pounds of CO2.

My circline bulbs will have another 12000 hours of service remaining, so the cost and environmental savings will be adding up, year and after year. Thrifty old me loves this!

Update:

Some interesting factoids on lighting from Adam Siegel, Dailykos blogger:
  • Lighting, today, accounts for 22 percent of US electrical use.
  • Much of this lighting is inefficiently used.
  • And, much of the lighting is inefficient. Compact Fluorescent Lightbulbs (CFLs) use roughly 26% of the electricity of traditional incandescent light bulbs (that date from the days of Thomas Edison) while lasting roughly eight times longer.
  • Light-Emitting Diodes (LEDs), which are penetrating into more lighting markets virtually every day, use roughly 20% of the electricity of CFLs for comparative lighting requirements. In other words, LEDs offer the potential for an over 90% reduction in electricity use from incandescent bulbs and will last almost over 50 times as long.

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