Published In December 2000
For decades, lighting designers, specifiers, contractors, and distributors regarded halogen lamps as best-suited for outdoor applications or as accent and display lighting. Their bright, striated light caused “sparkle,” but was far too harsh for general lighting purposes. Standard incandescent floodlights emitted a softer, more uniform distribution of light. However, their color was reddish yellow. But now, thanks to a cooler running halogen burner developed recently in Europe, the need for a compromise has ended. A new generation of indoor-friendly halogen lamps is emerging in the United States and European markets. These halogens retain their pure white color, energy efficiency (25 percent greater than incandescents), and longer life, while mimicking the soft, uniform light distribution of incandescents. And although they’re more expensive than incandescents, these lamps offset their higher cost premium through energy savings and longer life. Evolution of halogen The original halogen lamp was designed as a point source of light. All of its energy and heat emanated from a quartz burner about 3/8 inch in diameter. Burner temperatures averaged 1,800 degrees Fahrenheit and temperatures within a couple of inches of the burner far exceeded 1,000 degrees Fahrenheit. To handle the extreme heat, reflectors had to be made of metal or hard glass rather than the soft glass used in standard incandescents. In addition, the burner itself had to be placed away from the lens. This durable, efficient lamp emitted a bright white light, but its distribution was a tight, glaring beam (due to lens faceting) that left a ring of lines on the illuminated surface. Curing the glare In 1999, researchers in Lyon, France, and Tienan, Belgium, collaborated to develop the first halogen burner to operate at less than 1,000 degrees Fahrenheit. This 900 degrees Fahrenheit burner is made of hard glass rather than quartz, and its outer shell can now be made of “soft glass.” The design innovation was accomplished by increasing the size of the burner and lengthening the filament to distribute heat over a wider area. The lower burner temperature not only permits the use of soft glass, but also allows the burner to be placed closer to the lens, increasing light output. The end result is a unique lamp with the benefits of halogen and the soft look of standard incandescent floodlights. Halogens made softer A new floodlight with a low-temperature burner offers the white color, energy efficiency, and long life expected of halogens, but with the soft, uniform light distribution of the old R30s. Mini-halogens made transformerless Innovation is an evolutionary process. The first step in making a halogen lamp with a softer light was developing one that worked at 120V. This key innovation led European researchers to create miniature halogens in smaller sizes to operate on 120V rather than the usual 12V. These resemble the low-voltage MR16s commonly used for accent and general lighting in stores, public buildings, and high-end homes. But, they do not require a bulky, costly transformer system to be operational. No more compromises—all win A new wave of halogens has opened up all sorts of options for fixture and lighting designers in the U.S. Fixture original equipment manufacturers can now design more compact and cost-effective lighting systems than conventional low-volt halogen ones. Lighting designers can now simplify their designs, since they don’t have to compensate for remote mounting transformers or complicated power distribution systems. Development of a halogen burner that operates at 900 degrees Fahrenheit, half the usual temperature, has allowed new indoor-friendly halogen lamps to emerge in the U.S. and European markets. The halogen lamp pictured here, for example, retains its pure white color, energy efficiency, and long life, while providing soft, uniform light like incandescents. BONAWITZ is nrporation. He can be reached at firstname.lastname@example.org or by phone at (800) 922-6693.