Incandescent Globes’ One-Week Advantage
Those Frogs Still Prefer CFLs
Yesterday in my daughter’s science class, the subject of energy efficiency came up, and another girl in the class mentioned that she had heard that our house was full of energy-saving devices. So my daughter had to explain what we were doing at home to save electricity. One boy asked if manufacturing those compact fluorescent light bulbs doesn’t use more electricity than making a common incandescent globe.
She didn’t know the answer. And neither did I. But I was glad that the younger generation thinks about the carbon footprint of the products we buy, and I thought it deserved a little research. After much digging, I came up with some information from Osram about the electricity that goes into making their bulbs.
Osram says that they need 3.36 kilowatt hours to produce each 15 watt CFL. This is about two-and-a-half times the amount of electricity required to make the equivalent 75 watt incandescent globe, 1.29 kilowatt hours. An incandescent bulb is a simpler product, after all. So the advantage goes to the incandescent on day one.
It loses the advantage quickly, however. If you use the two bulbs for four hours a day, by the 9th day, the incandescent has used so much more electricity that it has lost its advantage. By the end of a year, my very rudimentary life-cycle analysis shows the CFL winning the race by 25.26 kWh to a whopping 110.79 kWh for the incandescent.
Even if you were burning these bulbs in Iceland, using carbon-dioxide-free geothermal and hydroelectric power, the CFL would be more environmentally friendly because it lasts longer and so one CFL is the equivalent of several incandescents.
If, like Noah, you know that the world is going to be swallowed up in a flood in a few days, an incandescent bulb is the green choice. If you think the flood might take a few more years as the Greenland ice cap melts, you should buy CFLs.
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May 8th, 2008 at 12:16 am
As someone who sells light bulbs for a living, I am less enthusiastic than most about compact fluorescent bulbs. This is due to the fact that the ones currently available contain significant amounts of mercury. If one of these bulbs should break inside of a person’s home, it could cause a challenging disposal situation. It is my belief that the technology should progress to a point at which the mercury levels are low or nonexistent before people changeover their entire homes. Another consideration is that as these bulbs burn out, they will most likely be thrown away as though they are normal rubbish and landfills will have incredibly high levels of mercury in their soil as a result.
A reply from GreenerHouse:
I disagree. My thoughts on mercury in CFLs can be found at http://www.greenerhouse.co.za/2008/04/09/quicksilver/ .
Let me quote from your own website:
If every household in the United States replaced just one light bulb with a compact fluorescent light bulb, it would prevent enough pollution to equal removing one million cars from the road. Generally, our U-Shaped and Spiral fluorescents use 1/4 the amount of energy with the same amount of light output. So, multiply the fluorescent bulb’s wattage by four and that is the incandescent bulb equivalent. These bulbs also generally last ten times longer than their incandescent counterparts.
May 9th, 2008 at 12:08 am
When I rebuilt my house about 8 years ago, I designed most of the lighting to need dimmers. This presents a huge problem for CFLs and I really have no elegant solution. The living room has three circuits – bayonet fittings behind pelmets and I tend to use only a single circuit and that at low intensity. But I’d really like to find dimmable CFLs.
May 9th, 2008 at 10:28 am
Dimmable CFLs exist, but I have not yet seen them in South Africa. Osram manufactures one, but no one sells it here. Osram SA tells me that they would bring out for anyone who orders 30 or so, but they will cost about R300-R400 each. The reason is the complicated electronics required to accommodate different varieties of old rotary dial dimmers. If volumes go up overseas, the price will come down. Fluorescent tubes can be used on dimmable electronic ballasts that are available in South Africa, using a push-button dimmer. I use one of these dimmers on concealed fluorescent tubes in my lounge.
May 9th, 2008 at 4:10 pm
My lounge has a total of 28 small incandescents distributed around it behind a pelmet. I won’t be changing them too soon! And as I said. I don’t use them all at full power TOO often! They are controlled by push-button electronic dimmers, so I guess I must experiment, but first I think I’ll check the science.
June 30th, 2008 at 7:58 pm
Most CFLs today on the market contain less than 5mgs of mercury and there are CFL options out there that contain as little as 1.5mgs of mercury- which can hardly be called a “significant amounts of mercury” considering that many item in your home contain 100s of times more of mercury including your computer. Mercury levels in CFLs can never be “nonexistent” since mercury is a necessary component of a CFL and there is no other known element that is capable of replacing it. But CFLs actually prevent more mercury from entering the environment. According to the Union of Concerned Scientist, “a coal-fired power plant will emit about four times more mercury to keep an incandescent bulb glowing, compared with a CFL of the same light output”.