Home | Archive | Subscribe

Light is a ubiquitous force—from the sun’s rays to the fluorescence that washes over grocery store aisles to the orange glow of street lamps guiding you home. It’s easy to take lighting for granted. But, there is a science behind lighting, and Kevin Houser, assistant professor in architectural engineering, is at the forefront of research in harnessing its science and power.

Architectural engineering as a formal discipline is relatively new—there are only 14 programs in the country.

Houser came to the University of Nebraska–Lincoln in 1999, impressed by the plans for the architectural engineering program and The Peter Kiewit Institute facilities, as well as the enthusiasm of the community. “I liked getting in on the ground level,” Houser said. He helped develop the program and designed the lighting lab with DLR, a local architectural engineering firm.

Upon entering the lighting lab at PKI, one is overwhelmed by a sense of mystery. The room is filled with the trappings of an advanced technological age—a state-of-the-art computer and lighting board, modular desks, an overhead projection system. Looking upward you see an array of light fixtures, a series of tubes, cylinders and bulbs humming as they come to life.

This lighting lab is one of the cornerstones of the College’s architectural engineering program. “This classroom has access to all the most recent lighting technologies,” Houser said. “And it is easier to explain difficult concepts when I can give students a hands-on demonstration.” The lab boasts 13 different overhead lighting systems that illuminate the entire teaching space, including phosphor-based fluorescent lights, high-pressure sodium lights, metal halide lights and an induction lighting system.

In his courses, Houser teaches students the fundamentals of lighting—color temperature and how the spectrum of lighting influences how an environment works. His courses also focus on how to design lighting systems environments for commercial buildings, schools, laboratories, roadways, gyms, malls and parks.

The considerations for each environment differ; however, the curriculum teaches the process of lighting design supported by a strong technical skill set. That skill set includes programming within established design criteria, including highlighting key architectural fixtures, guiding circulation and lighting transit routes, reinforcing an image or environment and making a space safe. “Lighting design is a balance between science and a more ethereal, artistic side,” he said. “It also requires divergent thinking and treating each project as a unique entity.”

The mock offices Houser and his research team built are shown here, illuminated under different settings. In the top row, the office on the left is lighted with the vision-tuned lamps Houser designed at 6500K and the office on the right is lighted with conventional lamps at 6500K. In the bottom row, the office on the left is lighted with vision-tuned lamps at 6500K and the office on the right is lighted with vision-tuned lamps at 3500K.
Beyond the classroom, Houser pursues his research by combining his knowledge of lighting systems with psychophysics, the quantitative branch of the study of perception. In his primary research project, which is being funded by a grant from the California Energy Commission, Houser seeks to fine-tune the radiant energy spectrum of light sources to get the strongest visual response with as low a light wattage as possible. “In this study, lighting quality and energy efficiency are treated as harmonious goals, not opposing forces,” he said. The ultimate objective will be to bring a new product to market, and to that end, General Electric is fabricating all the light source prototypes.

Houser’s motivation in this research is the belief that current methods for quantifying the visual effectiveness of light sources are inadequate for building lighting, resulting in wasted energy, pollution and less than optimal lighting quality. He approached the problem in a manner consistent with both energy efficiency and lighting quality by developing light sources that convert electricity into a spectrum of radiant power most favorable to human vision.

Houser relied on the concept of trichromacy, that all colors, as perceived by the human eye, are comprised of three basic colors—red, blue and green. The prototype lamps were designed to elicit the maximum response from these three visual response sensitivities using different phosphor, or fluorescent powder blends, which convert UV radiation into visible light on the inside wall of lighting tubes. The specific phosphors and their proportions controlled the lamps’ color appearance as well as the coloration of lighted objects and the perception of the light produced.

Houser and his research team, which includes Dale Tiller, associate professor in architectural engineering, graduate student Xin Hu and two U-CARE students, then built two identical, full-scale mock-ups of real offices in the lighting lab. A panel of expert observers was invited to the university to participate in an evaluation of the prototype lamps. The mock offices were illuminated with different settings, as the observers completed a survey instrument regarding their impressions, opinions and comparisons of the office interiors. On one side, conventional lamps were used and on the other, Houser’s prototype lamps. Participants did not know which was which.

The observers demonstrated a strong preference for the vision-tuned light sources Houser designed, reinforcing his theory that the amount of light can be reduced while maintaining the same visual effect. “It went well, and we got a great deal of compelling data,” said Houser. The results from the first phase were incorporated into the lighting system designs and a second round of prototypes are now being fabricated to demonstrate on a naïve panel of observers. Houser also plans to apply for a second round of funding to further his work. “This is a process that is predicated upon allowing for as much creativity as possible. There is no single solution and this type of work allows for exploratory thinking,” he said.

There is a bigger picture to the research Houser has undertaken. In recent years, the country has faced energy crises, most notably, in California. It is up to researchers to find ways to use available energy more efficiently. Lighting is responsible for 26 percent of the energy consumption in commercial buildings and 6 percent in residential and commercial buildings in the United States. More energy efficient light sources can make an impact. Conservative predictions estimate that the potential energy savings from the lamps Houser is developing, will be at least 20 percent above typical new technologies. This research also opens up possibilities for how employees perceive their workplace environments because lighting has been shown to affect office workers’ comfort and sense of well being, as well as their job performance. In many different ways, Houser is shedding light on the subject of possibility.