Lighting Research Center Lighting Research Center
    Volume 6 Issue 1
July 2002    
What luminaires are available for T5 lamps? - cont'd

The small diameter of T5 and T5 high output (T5 HO) lamps makes them nearly line sources with high optical controllability. Their quasi-line-source quality allows for a compact optical system that can accurately deliver the light emitted from the light source to where it is needed and therefore achieves a highly efficient optical design.

The higher output of T5 HO lamps may also help increase optical efficiency. Because a T5 HO lamp (5,000 lumens) has nearly 70% more lumen output than a T8 lamp (2,950 lumens), a one-lamp luminaire using T5 HO lamps may replace a two-lamp luminaire using T8 lamps (5,000 lumens) (see Do T5 luminaires perform better than T8 luminaires?). As the number of lamps in a luminaire decreases, the light control generally becomes more efficient and flexible. For instance, a one-lamp luminaire can be built with higher optical flexibility than a two-lamp luminaire. This optical advantage of one-lamp luminaires results in a wider batwing-shaped upward light distribution that can increase illuminance uniformity on the ceiling and floor. It also permits a higher mounting height (shorter distance from the ceiling). The ability to achieve high uniformity may let workplane illuminance easily reach IESNA standards.

If the optical system is well designed, the light output from a one-lamp luminaire using a T5 HO lamp can exceed that from a two-lamp luminaire using T8 lamps. As discussed in Do T5 luminaires perform better than T8 luminaires?, a two-lamp luminaire using T5 HO lamps often has more light output than a three-lamp luminaire using T8 lamps. When lighting designers specify these T5 HO luminaires instead of T8 luminaires, they can often use fewer luminaires per project, especially for large commercial projects.


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