And this have worked indeed. My apartment total power consumption have dropped from 1366 kWh to 808 kWh during last 5 years.
And this is without any other efforts. Stuff like turning off the lights every time I leave the room and things like that. Instead I'm sure I've been using all kind of electric gizmos even more during last years, bought Roomba etc.
I recommend this to other people, additional "work" that is needed when buying stuff is minimal. Surely saves money in long run, but environment too :)