This article from ArchLighting discusses a automated lighting control options that may save more energy than traditional manually controlled lighting.
“Lighting controls have always been an essential component of a lighting system, as they enable basic functionality: turning lights on and off, and dimming. But today, these functions are being automated in order to reduce energy consumption—a trend driven by sustainable design and commercial-building energy codes, which have made automatic controls a staple in new construction… ”
p.s. excellent illustration by Tang Yau Hoong