Is LMCE's existing support for motion detection cameras, used for alarm systems, a suitable foundation for supporting presence detection? So the cameras would always watch the rooms, and detect in which rooms there were people, and activate MDs, lights etc. Maybe even watch people leave, and switch from media/automation service into alarm mode until deactivated. Can it be calibrated to ignore moving pets, and just track people's presence in different rooms?
If it were really good, it could register users and track them individually, maybe by facial recognition. Or maybe people could wear watches or other jewelry/accessories that let LMCE distinguish among them. That's pretty far out, but even just telling whether there's >0 people in a room for more than just an alarm would be valuable.