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By Chris Johnson
November 2003 -
The very best technology is really only as good as its practical applications. Researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory are working on three ways to make efficient lighting technology more practical for everyday use in the nation’s institutional and commercial facilities.
Most table lamps are one-directional, shining light either up or down. But a two-lamp compact-fluorescent system developed by Berkeley Lab researchers is designed to shine light both up and down.
“To our knowledge, nothing currently available has both the high-performance lighting quality characteristics and energy efficiency of this new lamp,” says Michael Siminovitch, a scientist with the lab’s Environmental Energy Technologies Division.
The lamp uses two independently controllable and fully dimmable compact-fluorescent lamps (CFLs). One lamp’s light is directed downward to illuminate a desktop or other work surface. The second lamp’s light is directed upward to provide indirect lighting. An optical septum separates the two lamps, which allows three modes of lighting: downward only, upward only, or upward and downward together.
“Substantial savings can be had by turning off overhead room lighting altogether and using this lamp,” says Erik Page, a research associate. “The down light gives the user more than enough flux for most tasks, while the up light provides a low-glare ambient light that is ideal for computer environments.”
At full power, the lamp matches the combined luminous output of a 300-watt halogen floor lamp and a 150-watt incandescent table lamp, but it uses one-quarter of the energy.
Berkeley Lab’s Lighting Systems Research Group also has developed a safe alternative to the 300-watt halogen floor lamp, or torchiere. Torchieres have been cited by the Consumer Product Safety Commission in 100 recent fires and 10 fire deaths. Fires in university dormitories, where halogen torchieres are popular, have prompted a number of schools to ban them.
A typical halogen torchiere has a bulb temperature of 1,000 degrees. The new energy-efficient torchiere developed by Berkeley Lab researchers has a lamp wall temperature of 100 degrees, thanks to the fact that it uses CFLs rather than halogen bulbs.
In addition, the CFL torchiere is far more efficient than its halogen counterpart. While the average halogen torchiere consumes 270 watts and has a flux of about 2,700 lumens, the new CFL torchiere consumes only 67 watts and generates 4,000 lumens.
Finally, researchers at the Berkeley Lab have designed an indoor lighting fixture that capitalizes on the brightness and efficiency of the sulfur lamp, developed by a private manufacturer two years ago.
Consisting of a golf-ball sized glass globe filled with argon gas and a small amount of non-toxic sulfur, the microwave-powered sulfur lamp is four times more energy efficient and 75 times brighter than a conventional 100-watt incandescent bulb.
Limiting the use of the sulfur lamp in indoor applications is the lack of high-efficiency fixture systems that can comfortably deliver its intense light to interior spaces. Researchers recently developed a fixture that can be fitted with different reflectors to provide a variety of light distribution patterns.
“This system will make it practical for sulfur lamps to be integrated into common interior spaces, which should accelerate their market potential,” Siminovitch says.