22 August 2006
high light output ballasts and high output T-8 lamps when replacing
Replacing 2.4 m (8 ft) lamps with T-8 2.4 m (8 ft) lamps and electronic
Maintaining Uniformity. Carefully consider changes in lighting systems and
furniture systems so that lighting uniformity is not compromised. As shown in Figure 3-
6, a lighting system that provides uniform illuminance on the work-plane in one furniture
configuration may not provide the same uniformity in a different configuration.
3-10.5.1 In the case shown, an additional luminaire is required to adequately light the
center workstation. This increases the amount of energy required to light the same
area. In such a condition, the use of a semi-indirect, pendant system will provide better
uniformity and at the same time allow for flexibility in the workstation layout.
Figure 3-6. A change in furniture configuration affects the task plane illuminance
Low Ceiling Applications.
3-10.6.1 In some applications, the ceiling height may be low and cannot be increased
to accommodate pendant mounted lighting equipment. In these cases, the lighting
design should still try to address the issue of surface brightness. One way to achieve
surface brightness with low ceiling conditions is with recessed downlight / wallwash
luminaires. The reflector on these luminaires looks similar to a standard downlight, but
also uses a modification to light adjacent walls evenly. It is also designed to put light
high on the wall next to the ceiling.
3-10.6.2 Indirect lighting provides better visibility for offices and computer tasks than
parabolic luminaires. Additionally, the installation cost of pendants can be lower than
recessed troffer luminaires due to the reduced number of connection points. In low
ceiling applications where a semi-indirect pendant system is not feasible, consider semi-
specular parabolic troffers for lighting the interior of the space. Downlight / wallwashers
Used with permission. Hayden McKay Lighting Design.