Because commercial and institutional buildings operate primarily during daylight hours, with clearly defined schedules and specific tasks conducted in given areas, these kinds of buildings often lend themselves to comprehensive, systemized daylighting plans. In these buildings, daylighting—the use of natural light to save energy—makes sense.

When a building is flooded with well-controlled natural light, the amount of electricity needed for lighting can plummet. It’s estimated that 25% to 40% of a commercial or institutional building’s energy is needed for lighting, often at peak-demand prices; daylighting may save up to 50% of that, depending upon how natural light is used.

This is significant, particularly in view of the national energy picture. In the United States, electric lighting consumes about one-fourth of all the energy generated. According to the Rocky Mountain Institute, a nonprofit research and educational organization that fosters efficient use of resources, this usage equals the energy produced by 170 large power plants.

In addition, workers prefer brighter, more naturally lit environments. In fact, a number of studies support the idea that natural light has positive psychological effects on people. They suggest both that our brain perceives the color properties of natural light as “normal” and that we respond in a positive, physical way to its intensity.

The Lighting Research Center at Rensselaer Polytechnic Institute in New York says evidence shows that high light levels can contribute to good health, comfort, and productivity. It also points out that depression caused by seasonal affective disorder (SAD), a sometimes debilitating condition that occurs at high latitudes where people are deprived of sufficient winter daylight, can be successfully treated with high light levels.