Energy saving receptacles

I saw an energy saving solution to turning off areas where you have a set of devices with indicator lights on them where the duplex receptacle had an extra green wire and they were controlled by one switch at a central location so you could turn them off during periods when you were out or were not using them. They said this would reduce energy bill by 25%. I was wondering what you call this receptacle/switch system. The receptacles look just like a normal one but with additional wire and are installed just like a normal switch/receptacle. Thanks so much.