First Sulfur Lamp Lighting Fixtures Debut
November 22, 1996
By Lynn Yarris, LCYarris@LBL.gov
"This system will make it practical for sulfur lamps to be integrated into
common interior spaces, which should accelerate their market potential," says
Michael Siminovitch of the Energy and Environment Division. Siminovitch was one
of the principal investigators behind the concept and design of the new
fixtures.
The research was carried out under a partnership between Berkeley Lab and
Cooper Lighting, a major U.S. manufacturer. Although the new fixtures were
designed around the physical dimensions and photometric properties of a
specific commercial sulfur lamp, the technology can be applied to other highly
bright, energy-efficient electrode-less lamps now under development.
Indoor lighting accounts for about 25 percent of the electrical energy consumed
in the United States each year. It has been estimated that this consumption,
which costs about $30 billion, could be cut in half if existing lighting
systems were to be replaced with advanced energy-efficient alternatives. Two
years ago, a new type of lighting technology--called a sulfur lamp--was
unveiled and widely touted as the lamp for the 21st century. (It won several
awards, including a 1995 Discover magazine award for technological innovation.)
Consisting of a golf-ball sized glass globe filled with argon gas and a tiny amount of non-toxic sulfur, this
microwave-powered lamp was four times more energy efficient and 75 times
brighter than a conventional 100 watt incandescent bulb. It also outperformed
the best fluorescent lamps.
The sulfur lamp was invented by Fusion Lighting Inc., a small company in
Rockville, Md., which is now field testing a 1,000-watt version called the
Solar 1000. A major impediment to the wide-spread adoption of the sulfur lamp
has been the lack of high-efficiency fixture systems for delivering its light
to the interiors of commercial spaces. Sulfur lamps on display at the
headquarters of the U.S. Department of Energy, which helped fund the
development of the prototype, relied on a "light guide" to distribute the
illumination.
"Light guides are hollow tubes lined with a reflective material," says
Siminovitch. "Light from the source travels along the reflective material and
bleeds out to illuminate a space."
Illumination from a light guide can pose problems with glare and low efficiency
when used to light interior spaces, Siminovitch says. What has been needed, he
says, is an indirect low-glare system that could take advantage not only of the
high energy efficiency and brightness of sulfur lamps, but also of their high
CRI (Color Rendering Index), which puts them on a par with sunlight for quality
of illumination.
Siminovitch and two colleagues in E&E's Lighting Research Group--Carl Gould
and Erik Page--have developed a fixture that can be fitted with different
reflectors to provide a variety of light distribution patterns. The fixture can
also be mounted in various ways--on a free-standing kiosk, or on a wall or
ceiling--to provide a high degree of flexibility and suitability across a broad
range of interior lighting applications, from shopping malls to interior
complexes and offices.
The free-standing kiosks are especially adaptable. "A series of detailed
studies have been completed on developing optimized reflectors (for the kiosks)
to accommodate different ceiling heights," Siminovitch says. "By varying the
distribution geometry and the relative spacing of the kiosks, a large range of
illuminance can be easily delivered."
Siminovitch claims that a single kiosk could be used to replace from 10 to as
many as 30 conventional ceiling fixtures in an open-space office. In laboratory
tests, their light fixtures scored an efficiency rating of 85 to 88 percent,
which is as much as 25 percent better than the ratings for light guides, and
among the highest ratings ever scored for any white light source/fixture
system. Working closely with a manufacturer of light fixtures was a critical
asset to this research, Siminovitch says.
"Cooper Lighting brought insights and capabilities to the table as to how this
technology could be manufactured," he says. "It is a good example of how a
piece of science can become an actual commercial opportunity through an
industrial partnership."
Two of the new fixtures, outfitted with the Solar 1000 sulfur lamp, were
switched on during an official "lighting ceremony" in the spacious lobby of
SMUD headquarters on Nov.14. The fixtures are about eight feet tall and
resemble flashlights standing on end with their beams directed skyward. About
20 seconds after the lamps were activated in the ceremony, their spinning
sulfur light bulbs reached full speed and filled the lobby with
easy-on-the-eyes illumination.
Speaking at the lighting ceremony along with representatives from SMUD, Cooper
Lighting, and Fusion Lighting, were Berkeley Lab Director Charles Shank and
Martha Krebs, head of DOE's Office of Energy Research. Although funding for
this project came from DOE's Office of Energy Efficiency and Renewable Energy,
Krebs has been one of the champions for Berkeley Lab's lighting program since
her days here as an associate laboratory director.
Berkeley Lab scientists have developed the first lighting fixtures to
capitalize on the extraordinary brightness and remarkable energy efficiency of
the award-winning sulfur lamp. Prototypes of these new fixtures were installed
in the lobby of the headquarters of the Sacramento Municipal Utility District
(SMUD) and unveiled to the public last week.
