motion detections to add data to your footprint

Soap box ramble - Currently we use motion sensors to switch on lights or set of an alarm (intruder).  What will happen when these sensors knows it is you, and I mean you, you become uniquely identifiable.

Suppose your home sensors detect who is going into the room and set the lighting, TV to what you like.  It sends you a text to say which off the lights, or reminds you that the oven is on.  Will we see this as centralised big brother or that we can negotiate with our power companies to get cheaper bills when we move supplier by showing we are responsible and accountable?

Should the marketing be about reducing the standby energy production amount and therefore reducing pollution and extraction, or should we just be doing it anyway.  Is this technology looking for a problem?

Data, smart grids, identity, user behaviour.  Will you change if you knew your actions could count against you?

Will the cost of implementation be higher than any return?  As I said, mutterings of a mad man thinking out-loud.