A self-controlled energy efficient office lighting system

The fact that ambient sunlight can add significant contribution to the lighting level of an office, has motivated the authors into using the level of sunlight to control the demand of the electric lighting in an office. The control strategy is such that the level of the surrounding light increases the supply voltage, hence electric power consumption, to the electric lighting system is reduced. Similarly, when the surrounding sunlight decreases the supply voltage, the electric power consumption, to the electric lighting system is increased. The objective is to save the overall electric energy used for office lighting. Three controllers have been proposed to fulfill the previous control strategy. Two controllers were implemented and tested using LABVIEW. A third controller designed and constructed using discrete electronic components. All three controllers were self-regulated. The implementation of the control strategy in a university office showed that a 5.40% saving in the electricity bill was achieved whilst maintaining an almost constant lighting level.