System providing automatic and manual control of an illumination level in a space

An illumination maintenance system for maintaining a light level in a space of a building where the illumination sources include daylight and artificial light, the system comprising:

• a photosensor for measuring the light level in the space;
• a plurality of dimmable electric lamps providing artificial light to supplement the daylight in the space to thus control the light level in the space;
• a 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 controller for controlling the dimming levels of the plurality of electric lamps and the amount of daylight allowed into the space by the window treatment, the controller operable to automatically adjust the light level in the space towards a control setpoint in response to the light level in the space measured by the photosensor;
• and
• a manual control station for receiving an input to manually override the light level in the space to an override light level;
• wherein the controller adjusts the light level in the space to the override light level in response to the input received by the manual control, temporarily adjusts the control setpoint from a default setpoint to a temporary setpoint in response to the manual override of the light level, and subsequently adjusts the control setpoint from the temporary setpoint back to the default setpoint, where the temporary setpoint is equal to the override light level, the controller further operable to adjust the default setpoint in response to repeated manual overrides of the light level that result in repeated adjustments of the control setpoint.