Indoor Climate Control System

We spend a lot of energy keeping our houses warm or cold. (Depending on the climate.) Much of this goes to heating or cooling empty rooms.

A more efficient system would involve many independent ducts, an infra-red system, and some complex electronics. The system would only heat or cool rooms where a verified human presence was, as detected by the infra-red change in the area. It would prepare to heat or cool neighbouring rooms, but distant rooms wouldn't be heated or cooled at all.
If the electronics are complex enough, it could even learn your habits. It knows that you go to the kitchen every day at 7am, so at 7am, temperature control for the bedroom is switched off, and temperature control for the kitchen is on. At 8am, it switches to the bathroom, because it notices that you go there then. It switches off as you leave at 8:30. It knows that you arrive back around 6pm, so it switches on at 5:30.
More comfort, for less energy, and lower energy bills. Oh yeah.