The developer documentation provides details on how iBeacons can also provide information on far away the user is:
While a beacon is in range of a user’s device, apps can also monitor for the relative distance to the beacon.
You can use the information advertised by beacons to enhance the user’s experience of a particular location. For example, a museum app can monitor for beacons placed near the museum’s important exhibits. As a user approaches a particular exhibit, the app can use the relative distance of the beacon as a cue to provide more information about that exhibit rather than another.
Just swap museum/home and exhibit/room. Seems totally doable in a home environment.
I don’t even think iBeacons are available to consumers, but you might be able to buy some old ones off eBay and tinker with an custom app.
its a real shame they didn’t take off. A little early I suppose.