Daylight
and Electrical Lighting for
Task Oriented Spaces
For greatest
comfort in task-oriented spaces such as offices, distribute
daylight and most electric light indirectly – bounced
from the ceiling and walls. Reflective surfaces should be
light in color, preferably white.
Indirect
luminaires are available with wall or ceiling mounts. Choose
fixtures for high efficiency and wide light distribution to
minimize the number needed. T5 or T8 lamps with electronic
ballasts are good options. Efficient lighting power densities
typically range from 0.6 to 1.2 W/sq.ft.
Consider
space use and color quality to determine lamp color temperature.
For a cool ambiance, select lamps with a correlated color
temperature (CCT) of 4100°K; for a warmer atmosphere,
select 3100°K or lower. 3500°K is a common neutral.
Lay out
lighting control zones to supplement daylight variation throughout
the day; and coordinate them with HVAC zones and controls
for greatest economy. Typically, the maximum width of window
daylit zones is 2.5 times the window height. Toplit daylit
zones are seldom wider than 1.5 times floor-to-ceiling height
(depending on skylight and well dimensions).
Cautions
- Consider
power quality and compatibility with dimming ballasts.
- Requires
careful luminaire and sensor selection, placement and commissioning.
- Indirect-only
lighting system can seem bland; a small direct component
adds “sparkle”.
