Lighting Control

Retrofitting standard metal halide hi-bay fixtures to fluorescent hi-bay fixtures can generate energy cost savings of about 50 percent. How does reducing the resulting energy consumption by another 30+ percent sound—made possible by switching to fluorescent?
While tapping what remains arguably the hottest lighting retrofit market, distributors should understand the full advantages of fluorescent over probe-start metal halide, such instant-on and re-strike, which enables the use of switching strategies typically not practical with HID light sources.
Example: An occupancy sensor installed in each fixture senses a lack of occupancy in the area, or a photosensor senses high light levels due to daylight contribution, and either switches off the fixture or its outboard lamp. This provides a choice of energy savings and, if desired, flexible selection of light levels.
An additional 30-80 percent energy savings using occupancy sensors and 10-30 percent savings using daylighting controls can be achieved in a hi-bay fluorescent upgrade, says John Ireland, OEM channel manager for Watt Stopper/Legrand.
Mike Connolly, market development manager for Lithonia Lighting - Industrial Products, says inboard/outboard switching—achieved by separating circuiting ballasts within the same fixture, enabling 0/50/100 percent and 0/33/66/100 percent lamp output/power—is an inexpensive way to gain the benefits of flexibility from the lighting system. “For example, in a gym, light levels can be lowered for school productions or other needs outside of athletics,” he says. “Multi-lamp fluorescent fixtures offer many light level possibilities for user control, daylight harvesting and other applications.”
Occupancy sensing is the predominant strategy, particularly in applications such as distribution centers, warehouses and bulk storage areas. “Any area of 50 percent or less usage levels will accelerate the project’s payback period—even with relatively modest electric rates of $0.07 per kWh,” says Connolly. To optimize lamp life, particularly when the fixtures have high switching activity—more than six on/off cycles per day—programmed-start ballasts and a minimum 15-minute sensor time delay are recommended.
Passive-infrared (PIR) technology is standard in occupancy sensors used in hi-bay applications. “Besides its low cost, most spaces in hi-bay applications are within the line of sight of the sensor, large motion is usually being detected, and little adjustment is required after installation,” says Tom Leonard, director, marketing and product management for Leviton Lighting Management Systems. In hi-bay applications, the sensor may have a lens that provides 360-degree coverage for open areas or a narrow linear coverage for warehouse aisles