Abstract: The single zone lighting controller controls the lights in a zone or area integrating external control signals for daylighting and occupancy with a local override function. The daylighting signal is from a master photoelectric control, and occupancy signal is from a time-clock or electronic occupancy sensor; the local override, activated by an occupant provides a fixed override period before the single zone lighting controlled again responds to the external control signals. Shortly before the override period is over, the single zone lighting controller warns the occupant, e.g., by blinking the lights that the override is about to end.

Abstract: A system and method for providing substantially constant visibility over a ask area within a work area with time in which the visibility provided by natural daylight illumination is supplemented by a variable artificial illumination from luminaires to maintain a specified visibility. The background luminance and the difference luminance are determined as a function of the artificial illumination and the natural daylight. These relationships are used to determine the actual visibility at the task. The actual visibility is then compared with a criterion visibility and the intensity of the artificial illumination from the luminaires is varied to bring the actual visibility to the criterion visibility.