Your dad or grandpa probably taught you that youíd save electricity, or at least save money, by leaving fluorescent lights on for extended periods of time rather than turning them off and then back on.
That may have been true once, but not any more. The following, borrowed from Kansas City Power and Light, answers the question: Should I turn off fluorescent lights when I donít need them, or is it more energy-efficient to leave them on in an empty room?
Fluorescent lighting was developed in the 1940s when electricity costs were low. Design and manufacturing compromises in these early lamps caused them to burn out more quickly if switched on and off daily. Consequently, many companies left their fluorescent lamps on day and night. The electricity consumed -- given the extremely low power rates at that time -- actually cost less than the labor and material needed for lamp replacement.
Much has changed during the past half century in the world of lighting. Technology advancements and increased electricity cost have prompted the lighting industry to rethink the conventional wisdom of fluorescent lighting systemís operation.
Many people continue to believe that it takes significantly more electricity to turn on a fluorescent lamp than to operate the lamp for long periods. Modern fluorescent lamps, however, use little starting energy. Turning them off actually helps them last longer and lowers lighting energy costs. Researchers at the U.S. Naval Civil Engineering Laboratory have found that a fluorescent lampís initial "start surge" lasts only 1/120 of a second. The entire starting current for two-tube rapid-start luminaries lasts less than one second before it stabilizes. Consequently, Navy engineers assert that turning the lamps off for only one second saves the energy required to turn them back on.
A standard fluorescent lamp can run for 34,000 hours if left on 24 hours a day, 365 days per year. This equals 3.9 years of round-the-clock use. However, by turning the lamp off for 12 hours a day, it increases the overall longevity of the lamp to 6.8 years.
Not only does turning off fluorescent lights reduce lamp replacement costs, it also reduces electric bills. For example turning off a single one-tube light for only one-half hour a day can save about $3 in energy over the life of the lamp. In fact, the money saved by this routine is typically more than the price of a new lamp.
In short, you should turn off lights in your office or a room in your home when you leave, even if you leave for only a few minutes.
For more detailed information and additional data about fluorescent light use, visit the Kansas City Power and Light website at http://lighting.bki.com/
Article posted for the week of May 14, 2001.