Lighting Articles


In a typical commercial building, the cost of employing people outnumbers the cost of operating a lighting system by some 150 to one.

Therefore, while even as high as a 50% reduction in lighting costs using energy-efficient lighting can have a positive impact on the bottom line, just a one percent increase in productivity can dramatically improve profitability. Economists are acknowledging that the economic boom in the 1990s was driven by productivity gains.

Productivity can fluctuate between 50% and 200% at any given time for many reasons, including compensation, deadlines, the work environment, outside stresses, work relationships and so on. Lighting also plays an important part, both as an active participant and in a supporting role, and as such has been linked to Indoor Environmental Quality (IEQ) along with thermal comfort and indoor air quality.

The research is difficult to ignore. Here are a few examples of studies that demonstrate a relationship between productivity and lighting:

  • An American Society of Interior Designers (ASID) study determined that 68 percent of employees complain about the light in their offices
  • The 1989 Steelcase Office Environment index, (Louis Harris), showed that workers consider eye strain as the leading hazard to their health in the office
  • A Silicon Valley study found that 79% of computer users would like better lighting

By providing the best lighting design to support human interaction with the visual environment, we can support the goals of the space, including worker productivity, retail sales, occupant satisfaction, safety, security, reduced absenteeism, greater competitiveness in leasing--in short, turning good lighting into profit.

Lighting & Human Performance

Between 80% and 85% of our impressions of the world are visual. Light makes sight: vision requires a functioning human eye and light. Perception, however, depends on how a space is lighted. And perception, as they say, is reality. With Americans spending an average of 80% of their time indoors, most lighting is therefore electric--created, designed and controlled by humans.

The National Lighting Bureau states, "Lighting affects performance in two ways: directly and indirectly. The direct effects occur because lighting alters how well we can see, either by changing the stimuli to the visual system or by changing the operating state of the visual system. The indirect effects occur because lighting can gather attention; alter arousal, mood and behavior; and modify the body's hormone balance."

Therefore, the amount of light available to perform a task is one critical factor, and how the space is lighted is the other.

Lighting & Health

According to the National Lighting Bureau, lighting can affect physiological responses as well as visual (mental) perception.

In research by Dr. Levin, published in 1995, variable spectral power distribution showed significant biological as well as psychological effects. In fact, early fluorescent light sources put out concentrated output in the yellow-green instead of blue-green spectrum, believing that this concentration increased perception of brightness.

In addition, audible ballast hum and lamp flicker (usually seen in peripheral vision) can become a major irritant to people sensitive to it. According to Dr. Levin's research, almost 10% of the U.S. population is sensitive to flicker from magnetically ballasted fluorescent and metal halide lamps; these people are more likely to suffer from migraines.

Finally, seasonal affective disorder (SAD) is linked to a lack of light in the winter months; treatment includes a daily period of exposure to high light levels. A Lighting Research Center study showed that nurses at a hospital produced higher subjective responses of states of well-being, and those working the night shift scored faster and higher in performance tests, when exposed to a period of bright light.

Productivity vs Energy Savings

Renovating an existing lighting system may reduce the building's connected power load and ongoing energy costs, but improper solutions may harm productivity and satisfaction with interior spaces, negating the cost savings.

The National Electrical Manufacturers Association and the Lighting Research Institute produced a report in 1989 that concluded that building owners and managers were making "seriously erroneous decisions" concerning their lighting systems. The report cited putting emphasis on reducing lighting energy costs without sufficient concern for productivity.

The proper approach is encapsulated in the EPA Green Lights Program, which states that the goal of a retrofit or redesign is to reduce energy costs while maintaining or improving lighting quality. Earlier in this article, we stated that the cost of employing people in a typical commercial building outnumbers the cost of operating a lighting system by some 150 to one. Therefore, if we redesign the system to generate a 50% savings in lighting energy costs, we benefit the bottom line, but if the new lighting solution poorly addresses the goals of the space, which are related to task performance, then the cost of lost productivity and opportunity can negate and easily exceed the cost savings.

With this knowledge, our primary goal should be to improve worker productivity, funding the endeavor with energy savings whenever possible to justify the upgrade to senior management, which may view productivity gains as a soft payback because it is difficult to verify. Several leading corporations, among others, have embraced this thinking and reaped the benefits in their lighting upgrades:

Lockheed saved $500,000 per year in energy costs during a lighting upgrade in an engineering and development facility. The upgrade, however, also resulted in a 15 percent increase in productivity and a 15 percent decrease in absenteeism, as reported in Solar Today, May/June 1995.

West Bend Mutual Insurance reduced energy costs by 40% with a lighting upgrade, while increasing productivity in the claims processing department by 16%, as reported by the National Lighting Bureau.

Wal-Mart's Eco-Mart store saw sales become "significantly higher" on the half of the store lighted by skylights versus the half lighted by electric lighting, as reported in The Wall Street Journal, November 20, 1995.

As the industry proverb goes, "Light is for people, not buildings." With the proper approach to lighting and by acknowledging its importance to productivity, corporations can enjoy a second form of payback in addition to lighting energy cost savings--a happier, more productive workforce. -END-