Managers can schedule technicians — not the commissioning agent — to perform several key procedures to ensure the optimum performance of the lighting system:
Use correct replacement lamps. While all four-foot fluorescent tubes might look alike, they can have different performance characteristics. Most manufacturers offer several versions of their T8 lamps that vary by output, life and energy use. If the system is designed to use a particular lamp, keep using that lamp. Some lamps that use the lowest amounts of energy are not dimmable, so managers should not specify them for use with photocells. When changing lamps, they should review lamp specifications first.
Clean fixtures annually. A fixture's output can diminish by 10 percent a year just from dust accumulation, even in a relatively clean environment. If technicians clean only when they relamp, the system can lose as much as 40 percent of its output.
Verify other replacement components match the original. New ballasts, transformers and drivers at least should have the same performance characteristics. Instant-start ballasts typically use fewer watts than rapid-start ballasts, but they drive the lamp harder on start-up. In situations where lamps go on and off frequently, they are not a good choice, as they might result in more frequent lamp burnout, and the need for more frequent lamp replacement could torpedo the opportunity to save a few watts.
All ballasts have a published ballast factor. Maintenance and engineering managers can use it as a multiplier to determine whether a lamp actually will produce the predicted amount of light. It is tempting to specify a ballast with a lower ballast factor to save energy, but if the system produces only marginally acceptable light levels, the few extra watts of energy saved might result in complaints from occupants about low light levels.
Check dimming pre-sets periodically. This step can help verify they meet original performance requirements. Wall-box dimmers can have a high-end trim hidden behind the face plate that can extend the lives of incandescent lamps and save energy. Setting the pre-sets 10 percent below full output can double lamp life. For other light sources, they simply save energy because when the dimmer is set to full, the output actually is less, allowing for associated energy savings.
Check scene pre-sets to assure they meet original requirements. Dimming systems have pre-sets that, once set, rarely need changing. If that is the case, locking them either mechanically or electronically will prevent system problems. If technicians can change the pre-sets, they should check them periodically to see if they still comply with the sequence of operations. If changes in room activities force a change in the settings, technicians also should update the sequence of operations.
Denise Fong, IALD and LEED AP —dfong@candela.com— is principal of Candela, a lighting consulting and design firm headquartered in Seattle. She has more than 25 years of experience developing award-winning lighting designs.
Lighting Controls: Punch Lists, Commissioning, Recommissioning
Lighting Controls: How to Optimize Performance
Lighting Controls: Five Key Maintenance Practices
