The financial returns from energy-efficient lighting are well understood. Projections of return on investment for a lamp retrofit, for example, are relatively easy to make – and credible even to tight-fisted CFOs. Not as well understood or calculated is the impact of lighting on employee productivity. For most businesses, however, employee salaries represent a far larger percentage of operating expenses than energy, so a small improvement in productivity represents a far larger windfall.
For most people and activities, natural light is the best source of illumination, and LEDs and other technology are mimicking the quality of daylight at different hours of the day. LED panels that fit into standard 2-by-2 and 2-by-4 ceiling grids create the illusion of a skylight, even mimicking the effect of passing clouds. An Italian firm, CoeLux, has developed a thin coating of nanoparticles that simulates the diffusion of sunlight through the earth’s atmosphere. The resulting illumination is said to fool both minds and computers into thinking that the space they occupy is bathed in natural light.
Research has found that people complete tasks like character recognition and reading at a higher pace in natural light than artificial light. Daylight also appears to be less tiring on the eyes and psyche than artificial light. But these findings have not yet been accepted as a basis for projecting total ROI from lighting upgrades.
And indeed, that is not easy to do. For office work, where many kinds of knowledge-based activities are taking place, it is hard to quantify if, say, someone’s planning or problem-solving productivity improved due to better quality light. In other workplaces, like the auto assembly line where I had a summer job in college, it is easier. The factory was largely dark and cavernous, but I was fortunate to have a rare skylight directly overhead. On sunny days I noticed how much easier it was for me to scan numbers on a windshield card full of codes that told me where to drill holes in each car’s firewall. On cloudy days or on the nightshift, it was not so easy. I had to scramble to get all the holes drilled before the car had passed the reach of my air hoses. For this workplace, I imagine that management could correlate lighting improvements with such data as the number of vehicles with imperfections that had to be fixed further down the assembly line.
Given the tremendous financial potential of productivity increases in workforces, it will be exciting to see how researchers quantify the impact of better lighting on office work.