Indoor lighting is controlled according to the amount of daylight and presence of people.  Automatic lighting control, including turning lights off in window-side areas with sufficient daylight, or in vacant rooms, is an effective energy-saving measure.  Lighting control contributes to energy conservation in two ways: reduction in energy consumption for lighting, and reduction in air-conditioning loads caused by heat from lamps

 

 

link

http://www.gec.jp/ESB_DATA/EN/Tech/html/esb-130.html