View source for Lighting Control Options: Dimmers, Films, Filters

===How are dimmers used in exhibit areas?===
Interest in energy conservation has lead to more reliable and sensitive light dimming products. Dimmers can be used to control the light: (1) in an overall exhibit space; (2) falling on a particular object within  that space; or (3) within  an individual exhibit case. A dimmer is a particularly  good choice in areas of relatively little activity or where visitation fluctuates seasonally. Dimmers can be used to raise light levels in a gallery in advance of visitor traffic. Many situations can be satisfied with the use of domestic-type dimmers; some require commercial dimming controls. Some design options include:
* Light level: Dimmers may be set permanently to illuminate at a pre-determined light level; or may be programmed to increase the light output in response to an activation signal such as a lowering in ambient light levels or visitor request.
* Dimmers can be visitor operated, in which the visitor pushes a button to increase light; ultra- sonically controlled, in which movement activates the dimmer; or trigged by body heat or sound.1
* Sensor location: Sensors may be located in the ceiling, wall, or floor. In addition, a photoelec- trically controlled beam can be aimed across a pathway. False signaling can occur if the sensor is poorly located, for example in the air flow from a HVAC duct.
* Timer control: A timer can be set to turn the lights off or lower light levels after a pre-deter- mined amount of time or after a pre-determined length of inactivity  in the space.
* Sensitivity: The amount of motion, or other triggering mechanism, needed to activate the sensor is important. Sensors of different sensitivity are available and a few can be set for individual applications.
* Coverage: Sensors are available to cover both small and large areas.
* Compatibility: Dimmers are compatible with all incandescent lamps; more care is needed when choosing a dimmer for a fluorescent lamp. Lamp life may be shortened by use of a dimmer.
* Override: An override ability is desirable for special situations.

It is important to note that dimming a lamp usually shifts its color rendering index (CRI) towards the warmer end of the light spectrum. The lower light level, in turn, is perceived to be even dimmer. Choosing a lamp with a lower wattage, but with a high CRI value and a moderate chromaticity value will  provide a lower light level without color distortions. Lamp manufacturers and distributors usually offer technical advice for use of their products; also consult a lighting designer or engineer.

1 Green Seal’s Choose Green Report “Occupancy Sensors”.(February 1997): 1-7.