Patent ID: 7111952

Claim:
An illumination maintenance system for maintaining a desired illumination profile in a space throughout at least a portion of a day where the illumination sources include daylight and artificial light, the system comprising: a first sensor for sensing an illumination level in at least a portion of the space; at least one electrically controllable window treatment for at least one opening for allowing daylight into the space, the window treatment selectively altering the amount of daylight entering the space through the opening; a plurality of electric lamps providing artificial light to supplement the daylight illumination of the space, the electric lamps being dimmable and being arranged in one or more zones in the space, the zones defining predefined volumes of the space, each zone having at least one lamp; a control system controlling the at least one window treatment and the plurality of electric lamps to maintain the desired illumination profile in the space, the at least one lamp of each zone being controllable to a dimming level to achieve a desired illumination level in the respective zone according to the desired illumination profile; the control system controlling the plurality of electric lamps so that the dimming level of each lamp is adjusted to achieve the desired illumination profile and compensate for the daylight illumination in the space throughout at least the portion of the day; and the control system further operating to adjust the at least one window treatment in the event of sun glare through the opening to reduce the sun glare; wherein the dimming level of each lamp is selected by the control system from one of a plurality of lighting presets, each preset comprising a predetermined combination of dimming levels of the at least one lamp in each zone and wherein the control system adjusts the dimming level of the electric lamps toward a lighting preset that will result in an appropriate supplementing of the daylight illumination to achieve the desired illumination profile in the space; and the control system operating such that when the desired illumination profile within a predefined tolerance is achieved, the control system stops varying the dimming levels of the lamps and the adjustment of the window treatment.