New Light on the Gym
by Eric Strandberg
Providing good lighting for gymnasiums would seem to be a simple task, but designing energy-efficient, versatile systems that provide high-quality light can become rather complicated. With the advent of new light sources and fixture types, the old tools and rules of thumb become less viable.
The first type of lighting that should be considered for every new project is daylight. Gyms are generally large-volume, high-ceilinged, single-story spaces, making them excellent candidates for skylights. Often, their hours of operation coincide nicely with daylight availability.
However, there will be times when electric lighting is needed either to supplement low levels of daylight or for nighttime activities.
For the past few decades, standard practice has called for metal halide "high-bay" fixtures. When this kind of lighting first became available, it was a marked, if idiosyncratic, improvement over the old-generation fluorescent, incandescent, and mercury vapor lights that had been used until then.
On the positive side, standard metal halide offers high lumens per watt, (efficacy), and fairly long life, both of which are important to building operators. Because gyms are tall spaces, a degree of optical control is desired to distribute the light properly. Because a metal halide lamp is a point source, it is well suited for this task and, in contrast to older technologies, lends itself to lighting layouts that use fewer fixtures.
Problems with Metal Halide
Standard metal halide lamps also have less favorable properties. They take about three to five minutes to come to full brightness after they are energized. This strike time makes them a poor choice for spaces that use occupancy sensors and/or daylight controls.
If there is a power interruption, even for a second, the lamps need to cool down and then start the strike cycle again. This restrike process can take over ten minutes. This requires a redundant lighting system for safety and egress. >>>
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The University of Montana Recreation Center illuminated only by daylight.
Photo: Lighting Design Lab
An illumination simulation displaying the effect of fixture type A, standard metal halide high-bay.
Image: Lighting Design Lab
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