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Part 1: Lighting Quality Is Often Overlooked In Commercial Building Lighting Upgrades
By Karen Kroll
July 2013 -
It's not surprising that many lighting upgrades in commercial buildings focus on reducing the amount of energy the systems use. Lighting typically accounts for more than one-third of the energy consumed in these facilities, according to Energy Star. Along with boosting the energy efficiency of a facility's lighting systems, however, an effective upgrade or relighting also needs to consider the resulting light quality. Otherwise, occupants are likely to be unhappy; some even may be prompted to override elements of the system designed to save energy.
Rather than just lowering the lighting levels within a space, you need to first understand how the light is being used and then consider how to provide the illumination needed as efficiently as possible, says Halley Fitzpatrick, lighting consultant with Arup, a global engineering and design firm. After all, it's difficult to honestly claim an energy efficient upgrade is worthwhile if the lighting quality is so poor that the occupants can't do their jobs.
"If the perception of the environment adversely affects productivity," any money spent on a lighting upgrade was wasted, says Stefan Graf, principal with IlluminArt, a lighting design firm.
Once you have a handle on the type of work that goes on in a space, it becomes possible to identify ways to reduce energy use without compromising lighting quality.
You'll also need to decide how much to invest to meet those needs. A lighting retrofit — generally replacing components with more efficient ones — typically is less expensive but also provides fewer benefits than a more comprehensive relighting project, says James Benya, a principal with Benya Lighting Design. He says he's seen facilities in which this meant taking an inefficient and unattractive system and leaving it unattractive but making it more efficient.
If it's possible to invest a bit more, undertaking a relighting project can lead to a system that both looks good and wastes less energy. In a relighting, the new lighting system may be designed from scratch with the objective of lighting the space in a way that is both energy-efficient and aesthetically pleasing. Or as Benya says, "I like to get to 'wow.'"
Getting closer to "wow" requires knowledge of the elements of lighting quality. One is the amount of light available. Is it sufficient to allow occupants to use the space productively? A measure of this is "foot-candles," or the intensity of light falling on a surface equal to one lumen per square foot. For instance, offices in which accounting and similar work takes place generally require lighting levels of between 50 and 100 foot-candles, while hotel lobbies require between 10 and 20 foot-candles, according to the Illuminating Engineering Society.
Another factor contributing to lighting quality is the integration of natural light, as well as the quality of the electric lighting design, Graf says. Newer technologies make it possible to cost-effectively integrate electric light and daylight, Fitzgerald says. For instance, some newer light fixtures have daylight dimming capability, automatically adjusting to the amount of natural light coming into a space.
Color quality is another element of lighting quality. The lighting system should make the environment look and feel natural. Occupants also should look natural, rather than pasty or bluish.
Lighting: Energy Savings With No Regrets
Part 2: Harsh Lighting, Glare Among Quality Concerns In Commercial Lighting
Part 3: Lighting Controls, Occupant Involvement Are Big Pieces Of Successful Lighting Projects