Energy-Saving Lights

Thomas Edison's invention of the incandescent lightbulb revolutionized life and held sway for more than 100 years. But as the cost of electricity rose and climate change became an issue, the search started for more energy-efficient ways to produce light. Two of the answers -- compact fluorescents (CFL) and cold cathode fluorescents (CCFL) -- are existing types of bulbs used in new ways. Another answer -- the light-emitting diode (LED) -- has appeared in everything from computer screens to auto brake lights. But only with the recent development of diodes that gave off white light have LEDs been used as light sources.

Because each bulb type produces light differently, the light varies. Not all white light is the same -- the white we associate with an incandescent isn't pure white. It's rich in yellow, giving it a warm feeling that was lacking in early compact fluorescents. And where some bulbs shine light throughout the room, others shine light in only one direction, making them better suited for desk lamps than as general lighting. Bulbs are constantly improving, so check the shelves of your hardware or home center regularly for new developments that can save you energy and money.

Light-Emitting Diodes

Light-emitting diodes -- the same solid-state lights used on some computer screens -- are expensive but are also very promising as household lighting sources. The LED emits a focused beam. A 2.5-watt LED bulb can light up a small area as well as a 50-watt incandescent. The difference is that the LED illuminates only the small area, while the incandescent would light up the rest of the room. This makes LEDs well suited for reading lights, task lights, and even flashlights. Some general lighting LED bulbs are actually hundreds of LEDs in an array pointed in different directions. Current research is producing bulbs in the laboratory that are 6 inches square and more efficient than fluorescents.

Compact Fluorescent Lamps

Fluorescent lamps, which give off light when a gas inside them is electrically charged, have always been more efficient than standard incandescent bulbs. And now compact fluorescent lamps (CFLs) can be screwed into a standard socket. Using from one-third to one-fourth the wattage, a CFL can put out as much light as an incandescent. A CFL also lasts longer -- anywhere from 6,000 to 15,000 hours, compared with the 750 hours of an incandescent bulb. Early bulbs were slow to start, flickered, and gave off cold, white light. New bulbs match the color given off by an incandescent, light instantly, and do not flicker. Some bulbs are dimmable, and you can now get three-way compact fluorescents.

Cold Cathode Fluorescent Lights

Screw-in cold cathode fluorescent lights (CCFLs) are even more efficient than CFLs. Conventional fluorescents heat up a coil of wire, called a cathode, that emits electrons, which initially charge the gas in the tube. Unfortunately for the energy-conscious, power runs to the cathode the whole time the light is on. Cold cathode tubes, on the other hand, operate at a higher voltage, which overcomes the need to heat the cathode. A CCFL produces as much light as an incandescent bulb while using about one-sixth the wattage. CCFLs last 18,000 to 25,000 hours. Typically, the 8-foot tubes used in commercial lighting are cold cathode and are both efficient and bright. The compact screw-in models aren't quite as effective yet. At 8 watts, the most powerful bulb produces as much light as a 45-watt incandescent.


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