Lighting Research Center Lighting Research Center
    Volume 6 Issue 1
July 2002    
How can T5 lamps be used with recessed direct/indirect luminaires?

The thermal characteristics of T5 lamps that optimize their light output at 35° C (95° F) may make small, enclosed luminaires preferable for these lamps. Although small, recessed luminaires with parabolic louvers are popular for commercial lighting in Europe, few luminaires of this type are available in the United States because of their potential to create glare. One recessed T5 luminaire that manufacturers market in the United States is a luminaire with a large semi-cylindrical reflector and a metal mesh filter covering a T5 high output (T5 HO) lamp to soften its high luminance (Figure 17-2).

Figure 17-2. Direct/Indirect Recessed Luminaire

Direct/Indirect recessed luminaire
How can T5 lamps be used with direct luminaires for high-ceiling applications?

The high luminances of T5 lamps allow designers to use direct luminaires for high-ceiling applications, such as indoor sports facilities, gymnasiums, factories and warehouses, and retail spaces with high ceilings. These high-bay luminaires often have as many as six T5 high output (T5 HO) lamps in a small package with high-efficiency reflectors directing the light downward. Their high location decreases the apparent size of the high-intensity light sources, shields the light sources from the direct view of occupants, and therefore may reduce glare. These luminaires offer an alternative to high-intensity discharge (HID) luminaires. T5 lighting has a number of advantages over HID lighting. T5 lamps are dimmable if used with dimming ballasts, and they flicker less. They also have

  • better color rendering
  • longer life
  • better lumen maintenance
  • instant restrike capability
  • shorter warmup times

Although the initial cost of T5 lamps and luminaires may be higher than HID lamps and luminaires, T5 lighting can use as little as 50% of the energy that HID lighting does, especially if the T5 lamps are used with dimming ballasts, photo sensors, and skylights (Anonymous, T5 Fluorescent Lighting Outshines HIDs, 2000).

Can T5 lamps and luminaires be used for wall washing?

Wall washing with asymmetric luminous intensity distribution may be another application for T5 luminaires. Wall-washer luminaires, featuring luminaire apertures that are shielded by architecture or a low-brightness parabolic louver system from the view of occupants, can avoid causing glare.

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