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Factors to Consider when Lighting a Multi-Purpose Facility

By Jack Ries
Director, Product Innovation
Holophane

Multi-purpose facilities are just what the name implies—they are often the largest areas on a college campus and facilitate a multitude of functions. The room that is utilized as a classroom during the day may well double as the site for theatrical productions and sports evens in the evening and on weekends.

Because of this variety of activities, the lighting in a multi-purpose facility must be able to accommodate all of these functions. Whether you are lighting a new facility or retrofitting an existing multi-purpose area, below are factors to consider when designing a new system.

What Are The Tasks Involved?

How is the facility being used? Are students involved in the learning process here? Is the facility used for sports or community events—or a combination?

The new 60,000-square-foot field house at Franklin & Marshall College in Lancaster, Pennsylvania, is utilized not only for sports events (tennis, basketball, pole vaulting and lacrosse) but also for exhibits, music productions, commencement and banquets. In illuminating the facility, the light had to be bright enough for sports events, yet capable of being controlled for other activities.

“If students use the indoor jogging trace, for example, the school wanted to be able to provide recreational lighting. If only half of a basketball court is in use, the facility manager wanted the ability to light that area of the field house only,” said Steve Valeriano, electrical engineer and principal of Consolidated Engineers, West Lawn, Pennsylvania, the firm that designed the system.

In applications such as this, high vertical footcandles are needed so that players in a basketball game or volleyball competition can see the side of the ball as it approaches. Dark areas and shadows also must be eliminated.

At the Special Events Center at Fresno Pacific University, Fresno, California, the facility was illuminated with can-type high-pressure sodium fixtures, which Athletic Director, Dr. Dale Campbell, described as “shadowy and pinkish in color.”

“The room looked as though umbrellas had been installed on the ceiling and along the top of the stucco walls to block the light. Areas directly beneath the fixtures were very bright, but beyond those circles of light, the space was dark and full of shadows. This created serious visual problems during volleyball competition, in particular, because the ball would sometimes pass through two or three dark, shadowy areas as it crossed over the net,” Campbell explained.

Glare can also be a problem if the light is provided directly from one source. Uplight, which is a form of indirect illumination, not only helps eliminate glare but promotes uniformity by reducing the contrast between the lighting source and the surrounding area. Without uplight, you may have an appropriate amount of light on the surfaces near the floor, but the ceiling will appear dark and cavernous. Two different lighting systems may provide the same quantity of horizontal illuminance at three feet above the floor, but a system with uplight will improve the luminance of the ceiling and vertical surfaces.

The fixtures installed at the Franklin & Marshall facility are high intensity discharge units with a glass reflector that provides 15 percent uplight. Valeriano described the illumination:
“Lighting in the field house is very even. The glass reflector provide illumination in every direction, so there are no hot spots.”

How the facility is used will also determine the light levels needed. Illumination levels may be as low as 30 footcandles, with requirements as high as 100 footcandles.

What Light Source Is Best?

A number of light sources are available for lighting a multi-purpose facility, each with its own unique operating characteristics. However, most lamps on the market today can be categorized into three groups: incandescent, fluorescent and high intensity discharge (HID).

An incandescent lamp is the source used in most residents. The short lamp life (750 hours) and the low efficacy (the lumens provided per watt) often limit the suitability of this source of larger areas, such as a multi-purpose room or field house.

However, an incandescent source may be used to supplement another light source in this type of environment. At Franklin & Marshall, a combination of 400 watt metal halide (HID) units and 500 watt incandescent lamps were installed, with the incandescent fixtures considered “house lights” used for events such as lectures, dances and musical productions.

Fluorescent lamps produce light by activating selected phosphors on the inner surface of the bulb with ultraviolet energy generated by a mercury arc. The advantages of fluorescent lamps include improved efficacy and longer life (20,000 hours) than incandescent sources. The disadvantages of fluorescent lamps include their large size for the amount of light produced. In a high ceiling area where very high lumens are needed for tasks such as reading and sports, an HID source is usually better because fewer luminaires are needed.

HID sources include mercury vapor, metal halide, high-pressure sodium and low-pressure sodium. The benefits of HID sources are their high efficacy in lumens per watt and long lamp life (20,000 hours). HID is also a point source, which provides the opportunity for better light control. Light can be better directed where it is needed.

In many multi-purpose facilities, the users will want a white light, which is characteristic of metal halide. As mentioned above, the high-pressure sodium system originally installed at Fresno Pacific cast a “pinkish” color.

HID sources, however, have certain disadvantages. The units need a ballast to regulate lamp current and voltage. HID lamps will also have a delay before they reach full power after they are turned off. This makes HID sources an unacceptable choice if you are using a room for audiovisual presentations and must frequently turn the lighting system on and off.

Another consideration when choosing a light source is color rendition, which assures the occupants within the room can discern the true colors of various objects. These may include photographs in a book, banners hung on the wall, and even the colors of the uniform belonging to an opposing team during a sports event.

The higher the color rendering index, the more vibrant or closer to natural the colors in objects will appear. A light source with a color rendering index of near 100 has the same rendering capabilities as daylight. On the other hand, a light source with a color rendering index of 0 provides light with no color rendition, much like a black and white TV. It’s especially important to keep the color rendering index in mind when considering some fluorescent and HID light sources because the range of color rendering indexes varies greatly.

What Are The Physical Factors Within The Room?

The layout and dimensions within the room will likely influence the decision of what lighting system is best. The ceilings in most multi-purpose facilities are very high. The ceiling at Franklin & Marshall College, for example, is 50 feet to the roof, with fixtures mounted at 34 feet. The ceiling is an open design with trusses and exposed duct work. Here again, a fixture with uplight is essential to illuminate that space above the luminaires. Without it, the ceiling will appear dark and dingy. The uplight component not only increases the spaciousness in the facility but also promotes feelings of visual clarity.

If you are retrofitting an existing system, you may have to deal with recessed fixtures that have been installed in a finished ceiling. When these existing fixtures are removed, you will need a lighting unit that fits into the opening. This may be an HID source or a fluorescent system—depending upon the size of the opening. If the ceiling is high enough, you may be able to leave the recessed system in place and suspend new fluorescent or HID fixtures below the existing units.

Sometimes, artificial lighting in multi-purpose facilities is supplemented with daylight provided by skylights or windows. If this is the case, you may benefit from “daylight harvesting,” that is, turning off a select group of fixtures during the daylight hours so that only some of the luminaires are energized. To achieve this, the fixtures must be circuited differently and controlled by a photo cell or relay switch.

What About Budget?

Your goal in lighting a multi-purpose facility is likely to achieve the highest quality and most efficient lighting system for the dollars invested. While purchase price is certainly important, there are other elements to consider when examining your budget.

For example, what are the installation, maintenance and operating costs? As we mentioned above, an incandescent light source is likely out of the question as a primary source because of the short lamp life and low efficacy. The costs to consider include not only the purchase price for lamps, but also the expense of getting maintenance personnel to the facility and lifting them up to the ceiling to change the lamps.

There are several factors to consider when choosing between a fluorescent and an HID system. Lamp life is roughly the same. The installed cost for the two systems is also roughly the same. Typically, at mounting heights of 12 feet and below, fluorescent systems tend to make more sense. This is because fluorescent lamps put out less lumens relative to their size, and therefore, create less glare. However, keep in mind that with improvements in lamp technology—and especially biax lamps, fluorescent systems are making their way into higher and higher mounting heights.

Usually, HID systems tend to make sense at heights of 12 feet and above because HID is a point source. This height is necessary to get the spread required for the fixtures to meet the uniformity requirements of the space. There are exceptions to this rule, too. If the light level requirements are high, the HID fixtures can be brought closer together to avoid uniformity problems. It is important to pick the proper equipment to handle the special glare risk situation that high lumen sources at low mounting heights create.

The lighting system must match the owner’s requirements in terms of aesthetics and functionality. The owner or specifier will generally have a preference for the look of one type of system over another. And in terms of functionality, if instant on and/or variable dimming is required, at least part of the system must be incandescent or fluorescent.



 
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