Photo of typical commercial lighting design in the early 1970s.


Thirty years ago, "light ceilings" illuminated many stores and offices across the country, as seen in this 1972 photograph. When electricity costs began to rise during the Energy Crisis, businesspeople and lighting designers reevaluated this type of design.
© Duro-Test Corporation


We are seeking information about changes in commercial lighting over the last few decades. The following overview represents our starting point.

* * *

ALMOST HALF of the electricity used in a typical store or office building keeps the lights on, and commercial establishments account for about half of the lighting energy used in the United States. Conserving energy on commercial lighting means huge savings for individual business and the country as a whole. The pursuit of these savings has driven major changes in this area over the past thirty years. 

Early in the 20th century, many businesses kept the lights low to save money on electricity. But research in the 1920s and 1930s seemed to establish a link between lighting and productivity. Presented as "The Science of Seeing," the work of Matthew Luckiesh and others encouraged business owners and office managers to install brighter lamps and new fixtures. The brighter lights would increase productivity, they argued, and more than offset the increased energy costs.

The introduction of fluorescent lamps in 1939 helped both sides of this equation. Early fluorescents provided more than twice as much illumination per watt as incandescent lamps (about 40 lumens per watt to roughly 16 lpw). Some utilities even hesitated to promote fluorescent lights, fearing that the demand for electricity might suffer. World War II made the question moot -- fluorescent tubes were installed by the thousands in new war plants.

Homeowners were slow to adopt fluorescents, preferring cheap, simple incandescent lamps that produced warm colors. Stores and offices, however, came to rely predominantly on fluorescent lighting by the early 1970s -- the time of the Energy Crisis. With fluorescent fixtures already installed throughout their stores and plants, commercial users would seem to have been somewhat insulated from the rising electricity prices. Yet when the Energy Crisis hit, many business pulled the plug on "efficient" fluorescent lights. Why?

In the 1950s and 1960s, installing fluorescent lighting fixtures by the millions to boost light levels made sense, especially with energy prices low. And over the years, the efficiency of the tubes did improve -- from 40 lpw to about 70 lpw. As less efficient tubes burned out, they gave way to more efficient replacements. But fluorescent tubes are part of a lighting system, and one part of that system -- the ballast -- had changed little. Technically know as a "current-limiting device," the ballast controls the amount of electric current flowing through the tube.

Ballasts made before the 1970s were cheap to produce and reliable but, by today's standards, were noisy and wasted energy. The real problem of improving commercial energy efficiency in the 1970s and 1980s lay in the cost of upgrading ballasts. Installing new ballasts meant a greater investment of time and money than simply sliding in a new tube. Some required a new fixture, and so a substantial expense. 

Design practices of the time also played a role. Until the 1970s, energy was cheap and many businesses held fast to the belief that brighter work spaces made more productive workers. Not surprisingly, one popular design theory was the "blanket of light," which called for uniformly bright stores and offices. When electricity prices climbed, many building managers simply began yanking out fluorescent tubes, which usually disabled the entire fixture. This cut energy costs, but disrupted the lighting design. In some buildings, corridors took on the air of tunnels, and offices grew steadily dimmer or settled for zones of light and shadow.

Faced with growing demand for more efficient lamps and fixtures, manufacturers quickly brought several designs to market. Two early responses, Interlight's Phantom-Tube (a non-illuminating capacitor) and Sylvania's Thrift-Mate (an impedance-modifier mounted on a special lamp), were sold as replacements for one tube in a two-tube fixture. Both reduced energy consumption, allowed fluorescent fixtures to produce some light, and limited the damage to the lighting design.

Lighting manufacturers also quickly capitalized on some old research to improve fluorescent lamps. In 1948, Clifton Found and Wilford Winninghoff had found that changing the starting-gas in a fluorescent lamp from argon to krypton made the lamp more efficient. The idea stayed on the shelf until the late 1960s when a new manufacturing process reduced krypton prices. Lamps with altered gas mixes, such as General Electric's Watt-Miser series, were introduced in the mid-1970s. These lamps, however, sometimes performed poorly on existing ballasts.

In the same decade, the U.S. Department of Energy began to sponsor work on electronic ballasts through the Lawrence Berkeley National Laboratory in California. By driving lamps at higher frequencies, electronic ballasts made fluorescents more efficient, as GE's John Campbell and others had discovered in the 1950s. Electronic ballasts wasted much less power than conventional magnetic ballasts, and could also be more easily controlled with dimmers. Manufacturers introduced conventional ballasts that saved energy by cutting off power to the lamp's electrodes after ignition, known as a "cut-out" or "hybrid" ballasts.

The research at Lawrence Berkeley Lab and independent work done by several manufacturers ultimately yielded solid-state electronic ballasts (SSEBs). An important field demonstration took place at the main office building of Pacific Gas & Electric in San Francisco in 1978. Two DOE-sponsored electronic ballasts (made by Stevens-Luminoptic and IOTA-Excel) were installed in the building and competed successfully against a hybrid ballast and several conventional magnetic ballasts.

International competition produced the first compact fluorescent lamps. P.J.M.P. Verstegen and a team at Philips in the Netherlands developed a new family of rare-earth phosphors, while William Thornton at Westinghouse devised a rival "tri-band" phosphor design. Both innovations proved useful by making compact fluorescent lamps practical and allowing thinner linear tubes that could be used with the new electronic ballasts. A 1-inch diameter lamp coupled to an SSEB can achieve 100 lumens per watt, and has been the major technical factor in making commercial lighting much more energy efficient. 

Big business and big government contributed, too. Under the title "Demand-Side Management," electric utilities created a series of guidelines and initiatives to help customers change their patterns of energy use, install more efficient equipment, and save money. Programs like the Environmental Protection Agency's "Green Lights" promoted T8-SSEB systems, helping to boost sales and bring down costs.

Stores and office buildings have also installed dimmers, timers, and occupancy sensors to save energy, and some building codes now require them. Even incandescent technology has evolved; low-voltage "MR-16" lamps have become popular for retail shops and museums. Cooler lamps--incandescent or fluorescent--also save money by trimming the air conditioning bill.

Image made with lighting simulation program, 1992.Within the profession, some designers, engineers, and trade groups began to recommend generally lower lighting levels. Many designers moved away from the "blanket of light" approach to "task lighting," which puts light just where it's needed. A more sophisticated use of natural light in designs also helped to save energy. New computer programs, such as the Radiance software that generated this image, have let designers explore new options for creating effective and economical commercial lighting.

The stakes in commercial lighting have always been high, much higher than in residential lighting, which accounts for only about 6 percent of the energy costs of a typical household. This helps explain why businesses have generally been more willing than homeowners to embrace lighting innovations. New lighting equipment is an investment, and increased attention to the bottom line has been a powerful factor in promoting efficient lighting in the commercial sector.

We hope to document more of the recent history of energy-efficient lighting. You can help by responding to a few questions on one (or more) of the Collecting History pages on this site. If you helped to make or distribute efficient commercial lighting, or if you have used these devices in your business or workplace, we invite you to give us the benefit of your experiences. Your responses will help us better understand both the history -- and the consequences -- of this technology.


© 2001 Smithsonian Institution
Last Updated: January 2001