Electro/Telecom Industry Trends
February 2004
Shedding Light on Lamp Options
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Since Thomas Edison first developed the incandescent light bulb over 120 years ago, lighting has played an important part in the design and construction of indoor and outdoor environments. But for all its advantages, electric illumination comes with a hefty price tag — nearly 30 percent of the energy consumed in the U.S. is used to produce light. With energy prices rising, and news of blackouts occupying headlines, there is renewed interest in lighting that can reduce energy consumption. Options do exist — and more are on the horizon — that can dramatically cut energy use, but good energy management requires more than simply swapping out one type of lamp for a more efficient version.
Lamps — known as light bulbs or fluorescent tubes by consumers — come in an endless number of shapes, sizes, and varieties. They can typically be placed in one of six groups — incandescent, fluorescent, mercury vapor, metal halide, high-pressure sodium, and low-pressure sodium. Incandescent lamps represent the oldest type, with the basic model working much in the same way as the one first created by Edison. While incandescent lamps are inefficient at converting energy to light, with 90 percent of energy used producing heat while only 10 percent produces light, they are cheap and are used extensively, especially in homes. Tungsten halogen, reflector, and parabolic aluminized reflector lamps are just several of the newer types of incandescent lamps on the market. Along with being somewhat more energy-efficient than the original incandescent lamps they are designed to replace, some of these lamps also have longer operating lives.
Besides incandescent lamps, which directly convert electricity to light, all other types of lamps operate using a process called gas discharge — the tubes are filled with gasses, which an electric current activates, causing them to glow or “fluoresce.” These lamps all employ what is known as a ballast to alter and control the incoming electricity. Gas-discharge lamps are much more efficient than incandescent lamps since they produce more light while using less energy. In the past, however, many of these lamps were not considered suitable replacements for incandescent lamps because of how poorly colors appeared in their light. Known as color rendition, this indicator of how colors appear is important in evaluating where and how lamps can be used. Changing technology has improved the color rendition capabilities of some fluorescent and metal-halide lamps, allowing them to be used much more extensively.
Lamps with lesser color rendition capabilities still have an important role to play. High-pressure sodium lamps, which are a more efficient option than fluorescent, mercury vapor, or metal halide lamps, are often used outdoors. Low-pressure sodium lamps are even more efficient and are used in areas where color rendition is not important, such as in warehouses.
New electronic ballasts are also improving energy efficiencies. This is an important development for America’s offices, which are almost exclusively illuminated by fluorescent lamps. Besides eliminating the noise and flicker associated with older electromagnet ballasts, electronic ballasts can increase energy efficiency by more than 25 percent. Many of them also allow for the dimming of fluorescent light output, increasing the possibility of energy conservation even further.
Advanced technologies are also on the horizon. The Department of Energy, through its Building Technologies Program, is working with industry organizations to promote the development and application of advanced light sources, ballasts, lighting fixtures, controls, and distribution systems. Projects range from increasing the efficiency of incandescent lamps to improving the capabilities of organic light-emitting diodes (OLEDs) for general lighting.
While there are a number of more energy-efficient options available today and more coming, it is not a straightforward task to cut energy consumption by simply replacing one type of lamp with another. Different types of lamps are more appropriate for different types of tasks and the array of configuration options can be overwhelming.
There are a number of resources to help, including those provided by the National Electrical Manufacturers Association (NEMA) and the National Lighting Bureau (NLB). The NLB in particular offers several informational publications designed to help organizations better understand their numerous lighting options.