UFC 3 -520-01
June 10, 2002
relative to ordinary operation, is estimated to save 5 percent to 10 percent of lighting
energy as compared to a non-dimmed system. Most lighting systems can be switched
or dimmed, although some syste ms work better than others (refer to Table F -3).
Table F -3. Control Considerations for Various Light Sources
Light Source
Switching Considerations
Dimming Considerations
Incandescent and
Inexpensive. No operating
Low cost and simple. Will extend lamp life.
tungsten halogen
issues.
Dimming is full range and appealing. Some
lamps
energy savings.
Full size and U-bent
Inexpensive. Frequent
Requires electronic dimming ballast and
fluorescent lamps
switching can shorten lamp
matching controls. Dimming can not
life.
decrease light below a minimum point
without flicker. Some color shift when
dimmed. Properly matched systems can
dim lights smoothly and effectively to 10
percent.
Compact
Inexpensive. Frequent
Requires electronic dimming ballast and
fluorescent lamps
switching can shorten lamp
matching controls. Dimming can not
life.
decrease light below a minimum point
without flicker. Some color shift when
dimmed. Properly matched systems can
dim lights smoothly and effectively to 5
percent.
HID lamps
Inexpensive. Due to warm up
Requires special ballasts and control
and recycle times, access to
systems. Dimming can not decrease light
switches should be limited.
below a minimum point. Energy efficiency
of source diminishes with dimming.
Undesirable color shift and lamp life
problems are likely.
F-12.1.2 Scheduling controls determine the time that lights turn on and off. Time
and complete building automation systems. It is estimated that, compared to manual
switches, time scheduling saves about 10 percent to 20 percent of lighting energy.
F-12.1.3 Motion sensors are scheduling controls activated by the movement of people.
Wallbox sensors are best suited for small rooms, such as private offices, and can be
used in place of a standard wall switch. Ceiling and high wall/corner sensors are more
generally applicable and tend to work better. Multiple detectors can control the same
lights, covering a large area. It i s estimated that motion sensors save around 15
percent of lighting energy in a large room and up to 30 percent in smaller rooms.
F-12.1.4 Photoswitches turn lights off when sufficient daylight is present. This method
is usually used for outdoor lighting but can be used in indoor applications where lights
must be turned on at night.
F-18
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