No one doubts that fluorescent light bulbs are far more efficient than traditional bulbs, which waste about 90 percent of their energy on heat. Many people have significantly reduced their electric bills by switching to CFLs. But there are situations where CFLs are not the best option.
CFLs work on the principle of fluorescence. An electronic ballast in the base of the bulb generates an arc between two electrodes inside a glass tube filled with gas. The arc excites mercury atoms in the gas so that they give off ultra-violet (UV) energy.
Because the UV rays are invisible, bulb makers add a white phosphor coating to the inside of the glass. When the UV strikes the phosphor, it glows, or fluoresces, in the visible range of light.
CFLs and Mercury
One of the biggest reasons to buy CFLs is that because they use so little energy, they reduce overall emissions of mercury into the air from power plant smoke stacks. However, as noted above, all fluorescent bulbs contain a tiny bit of mercury, which is highly toxic.
A report by Yale University researchers in 2008 concluded that, depending on the state or country involved, the use of CFLs may actually increase total mercury released to the environment.
The reason is that power plants use different fuel sources, which release different amount of mercury into the air. In some locations that use cleaner coal, or that have few recycling options, the mercury leaked into the environment from landfilled CFLs could actually surpass the amount saved by using less electricity from power plants.
Cleanup and Recycling of CFLs
Although the amount of mercury in a CFL is much less than that in a can of tuna, CFLs are considered household hazardous waste. By law, they must be either be recycled or taken to an approved hazardous waste disposal site.
If a CFL breaks, the U.S. Environmental Protection Agency website recommends special steps to follow for cleanup. These steps include airing out the room, putting all debris and cleaning materials into a sealed jar or double plastic bag, and avoiding the use of brooms or vacuum cleaners that might stir mercury into the air.
In addition, the Maine Department of Environmental Protection website recommends disposing of the carpet, rug or bedspread on which a CFL breaks. It also suggests that CFLs might not be appropriate in rooms used by infants, small children or pregnant women, who are more susceptible to mercury poisoning.
Many hardware stores and local disposal sites accept CFLs for recycling, and some companies now sell pre-paid shipping boxes addressed to recycling plants. Unfortunately, not everyone has easy access to these options, so about three out of four CFLs end up in landfills, where the mercury gets leached into the soil and groundwater.
CFLs on Dimmer Switches
Many homes today contain dimmer switches. Using these switches saves energy by reducing the amount of power needed for lighting. But most CFLs do not work on dimmer switches, and may actually damage this kind of switch.
Some light bulb companies make CFLs that work on dimmer switches, but they are more expensive and often disappointing. They don't dim smoothly, but drop down in just a few, abrupt steps.
CFLs Don't Look Natural
Fluorescent lights normally give off blue-tinted light, whereas incandescent bulbs give off a yellowish light. Some people may not feel comfortable in the "atmosphere" of CFL bulbs. To reduce this effect, manufacturers are now offering CFLs in a color range of warm to neutral to cool.
Another problem with CFLs is that they don't show objects in their true colors. Bulbs are graded by their color-rendering index (CRI), with a grade of 100 being the color an object appears in daylight. Incandescent bulbs have a CRI of near 100, but CFLs are often graded with a CRI of 85 to 90.
Not all settings require a perfect CRI, and in many cases the color won't make much difference. By trying CFLs marked as either "warm" or "neutral," the blue color of CFLs might be avoided.
CFLs in Cold Climates
CFLs don't work well outdoors in cold weather. During the winter they take a long time to warm up to full power in garages, porches and outdoor light fixtures. CFLs are now labeled with their lowest operating temperature, and some are made especially for cold locations.
CFLs may not save as much energy in cold climates because they don't produce much heat. According to a study by the Canadian Centre for Housing Technology, houses with five CFLs replacing incandescent bulbs will have an increase in energy costs for heating in winter.
In summer, the study showed, CFLs significantly reduce power requirements for air conditioning. So although they do have a positive affect on total energy use throughout the year, lighting savings with CFLs are reduced because of the extra amount of power needed for heating.
For more information, see CFLs Can Cause Physical Symptoms.
For consumers who want to save energy and money, even where CFLs won't work, find energy saving alternatives to CFLs here.
Holly Martin - Holly B. Martin's blog, www.scienceshift.com explores the world of science beyond the fringe.
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