For instance, older workers and workers performing highly-detailed tasks need more light to perform their respective visual tasks. Tuning is accomplished with dimming devices. Daylighting is the act of turning lights off or reducing power to electric lights in the presence of natural daylight from windows and skylights. Daylighting controls employ a photosensor-controller device, linked to a switching or dimming unit that varies electric light power in response to natural light. A lumen maintenance control strategy reduces lighting power at first, gradually increasing to reach full power at the end of the maintenance cycle.
Illuminance remains constant throughout the cycle.
Control is achieved through the same type of hardware used for daylighting controls. Most any type of control device can be employed to limit demand. However, automatic dimming controls allow this to occur without occupant awareness. However, lighting power can be reduced substantially at night, as human eyes are night-adapted and do not require as much light in those same areas. Adaptation compensation control strategies employ dimming devices or switching relays combined with automatic timers to vary illuminance accordingly.