Lighting is one of the critical components of green building design, accounting for 23% of a typical office building's energy use.96 Lighting design is also an important factor in raising the productivity level of office workers. Over the years, recommended illumination levels have gradually come down, from the brightly lit fluorescent workplaces of the 1970s, where 100 foot-candles was the recommended luminance, to today's standard green building design of 30 foot-candles at the work surface. In modern lighting design, especially with underfloor air systems, there can be task and ambient lighting, as well as lighting displays for special effects such as highlighting public art. Of course, many people can work well in illumination below even 30 foot-candles, provided that the light is natural daylighting.
Research at Carnegie Mellon University demonstrates the importance of lighting quality for productivity. Given that costs for people's salaries and benefits are typically 100 times a building's energy costs, even a small gain in productivity can be the equivalent of paying the energy bill several times over.
Productivity gains from implementation of high-performance lighting systems.
New lighting technology also has an impact on energy use and lighting quality. Elsewhere, we discuss the advent of light-emitting diodes (LEDs), a strong candidate to replace other lighting technologies in many uses. The advent of T-5 high-output lighting in the early 2000s cut 37% of the materials out of a fluorescent light by reducing the diameter from 1 inch to 5/8 inch (and provides a brightly lit lamp reminiscent of the light sabers used by Luke Skywalker and Darth Vader in Star Wars). On a trip to Alaska in 2007, I toured a building that effectively combines T-5 lamps with direct-indirect lighting fixtures, in which light bounced off the ceiling, as well as shone directly out the bottom of the fixtures, providing the effect of a dispersed lighting system with fewer fixtures.
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