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Featured Lighting
Consultations: Seattle Tennis
Center Courtlite In September of 2002 Soheila Ghassemikia of Seattle City Light approached the Lighting Design Lab looking for help lowering the power load at the Seattle Parks Department facility, the Seattle Tennis Center. As is common practice, the tennis center is lit with 1,000 watt Metal Halide (MH) fixtures pointing upward. The light reflects off of the white ceiling and delivers very even and diffuse illumination to the playing surface. When done properly, an indirect system such as this, has a good quality of light, but it requires a lot of fixtures to achieve the proper light levels. Needless to say the power density is extremely high - over 1,000,000 KWh per year. After briefly looking at a few other indirect systems (Pulse Start MH and T5/HO), we determined that a significant power savings could not be achieved w/ out sacrificing significant light quantity (i.e., the light levels dropped too much). We then began looking at direct lighting systems, in particular a potential solution from Gary Fowler of Pacific Energy Solutions. This system uses banks of T5HO lamps that run parallel to the field of play in a bracket that holds them at a 45 degree angle to the floor. With 4 lamps per 8 linear feet the system uses only about a third of the power of the 1,000 watt MH indirect system, while still maintaining similar light levels. An area of concern was the quality of light. We knew that the T5HO system had better color qualities than standard MH, but we were concerned about possible glare. The fixtures are made by 1st Source, and use a specular reflector with a 12" X 48" prismatic lens. Gary Fowler, an energy consultant, brought an 8 foot section to the Lab for review by Seattle City Light. We hung the fixture in our Mockup room and raised it to a height of about 15 feet. The first impression was that glare is not a problem with the 4 lamp fixture. Pacific Energy Systems and 1st Source then worked with Seattle City Light and the Seattle Parks Dept. to present a full-scale mockup at the Tennis Center. They installed the lighting in one of the five courts, turned off the lights of the adjacent court, and left the other three lit in the usual way. My initial impression was that the court lit with the new system (direct T5HO fluorescent) was brighter (especially on the court level) and gave much better contrast of the lines on the court, the net, and the ball. The ball was more uniformly lit and its color was enhanced (as were all of the colors in the court area). As was born out in the initial mockup at the Lab the lens on the fixture, when viewed parallel to the field of play was bright, but not glaring (even with six lamps per 8 feet illuminated). The only time it appeared "excessively" bright was when I looked straight at it when all six lamps were lit. But this is an unusual viewing angle and I don't think it would occur much during "normal" play. No lighting is perfect in every way, even playing outdoors one can encounter glare and imperfect light distribution. The minor amounts of glare encountered with the new system were far outstripped by its advantages. Better color properties, much lower power consumption, and a longer maintenance cycle. We look forward to seeing a full retrofit of the Tennis Center seeing the long term results and benefits of the new system. |
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Above: The Settle Tennis Center is open 16 hours a day, 7 days a week. Existing lighting is perimeter T12VHO fluorescent and 1000W metal halide indirect. Total annual kWh per year is over 1,000,000.
Above: A sample T5HO fixture was brought to the LDL for evaluation by our lighting specialists and staff from Seattle City Light. The initial concern was over the amount of glare from the large number of T5HO lamps.
Above: The T5HO fixture on a table next to a wall to see the distribution from the luminaire. Even though the light is intended to be mostly direct, the angle of the luminaire reflectors shows that there will be some uplighting contribution.
Above: consultants from Pacific Energy Solutions discuss their ideas with Seattle City Light analyst Soheila Ghassemikia .
Above: Seattle Parks Department and Seattle City Light personnel evaluate the proposed lighting system demonstrated at the Seattle Tennis Center. Note that the existing metal halide system is in place, but is turned off.. |
