Lighting control plays a strategic role in the operation of a modern office environment. It ensures that the visual performance of the lighting equipment is appropriate to the needs of the occupants, while simultaneously conserving energy. By day, illumination levels can be maintained dynamically, both to comply with relevant lighting and energy codes, and to ensure optimum worker performance. After hours, the control is more aggressive toward energy conservation, but still accommodates the needs of maintenance and security staff and late night workers. It is no longer socially acceptable or commercially astute to burn all of the lighting throughout the day and for half the night, yet a feeling of personal security and well being must be protected. Workstations co-exist with traditional enclosed offices in many buildings. Appropriate strategies for the lighting controls must be determined according to the specific needs of each application. The workstations typically share an array of fluorescents overhead while corridors, lobbies, meeting rooms and amenities an have a variety of local lighting types and technologies.

System outline
The boardroom includes a cabinet that houses audio-visual equipment. A ceiling-mounted data projector casts images on to a motorized screen, which is retracted when not in use to provide access to a whiteboard.
Lighting over the audio-visual cabinet and the boardroom table comprises narrow beam low voltage down lights, which enables precise illumination over work areas. Down lights are also used for general room lighting and cold cathode neon, concealed in a ceiling coffer, provides perimeter lighting around the table. Separate control allows fittings near the screen to be dimmed when the projector is being used.

Controls
Control of work space and decorative lighting
Control of data projector via RS232
Control of projection screen
Control of window curtains
Infrared (IR) remote control

Control panels are located adjacent to the entry doors (CP1 & CP2). An infrared remote provides control for those seated at the boardroom table. Ceiling mounted sensors (S1 & S2) pick up signals from the IR remote.

Each of the five windows is fitted with motorized curtain track to reduce natural light levels during projector operation. Two control channels are used per curtain; one for direction of travel and the other for motion. This enables partial closure of the curtains and de-energies the motors at the end of travel so that motor limit switches are not relied upon constantly. The figure along side illustrates the motor control circuit.

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