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Three CFL myths busted

May 11, 2009 10:18 by human

The benefits associated with using compact fluorescent bulbs are hardly a secret. Each CFL uses about 75% less energy than an incandescent bulb, lasts longer, and saves about $30 over the course of its lifetime.  

For every benefit, though, it seems there is a compelling reason to avoid these energy efficient bulbs. In most circumstances, it's simply a case of mispercentions blown out of proportion. 

Here are the facts behind three common myths: 


Myth: Compact fluorescent bulbs are a major safety hazard because they contain mercury.

Fact: Yes, it's true that CFLs contain tiny amounts of mercury, and if a bulb breaks you will be exposed to the neurotoxin. But, just how dangerous is a broken bulb? Researchers at the Lawrence Berkeley National Laboratory set out to answer that question. They compared how much exposure you'd get from breathing in the amount of mercury released from a broken CFL bulb to how much mercury you'd take in from eating Albacore tuna.

If you do a common sense job of cleaning up (open the windows, clean up, and remove the debris), then your mercury exposure would be the equivalent of taking a tiny nibble of tuna, according to Francis Rubinstein, a staff scientist at Berkeley Lab. What if you did the worst job possible, say closed all the doors and smashed the bulb with a hammer? It's still no big deal, says Rubinstein, who points out that it would be the equivalent of eating one can of tuna.

Myth: You don't really save energy by using compact fluorescent bulbs because they take so much energy to make and ship.

Fact: The amount of energy required to manufacture, transport, and dispose of an item is called "embodied energy." For a CFL, the embodied energy is about 4% of the bulb's total energy use, according to an essay published in LD+A, the magazine of the Illuminating Engineer Society, last December.

The scientists found that it takes about 1 to 2 kilowatt-hours of energy to make and ship a compact fluorescent bulb (even those made in China), but it saves at least 200 kilowatt-hours of energy over its lifetime. At the typical price of electricity, it costs about 25 cents worth of energy to make a fluorescent bulb, a trivial amount when you consider the tens of dollars of electricity saved over the life of a CFL, says Rubinstein, who co-authored the essay. 

Myth: It's not worth it to replace your incandescent bulbs with more energy efficient lighting because you'll end up spending more on heating bills to make up for the lost heat thrown off by incandescent bulbs.

Fact: It's true that incandescent bulbs give off heat that can help to keep your home warm. But, Rubinstein points out that it's only a tiny amount. There are a number of factors that can impact the amount of money and energy you save by switching to CFLs (or other more efficient lighting).

If you live in a cold climate (in an insulated house), losing ambient heat from those old inefficient incandescent bulbs may increase your heating bill slightly, but you'll save more on overall energy costs because of the electricity you'll save on lighting. If you live in a warm climate, you might even rack up more savings since you won't need to use as much air conditioning. Rubinstein's bottom line: You're almost always going to save money when you replace an incandescent with a CFL, but you may not save quite as much during the heating season in a cold climate.