Why Communicate? - what lifts a Smart House or dwelling beyond one  merely fitted with appliances/systems with controls, is the ability to usefully link them together.
To interactively control them with a degree of pre-programming.

This can be simple or complex, depending on application and flexibility required.
For this to happen - even at the most basic level of Smart Housing -two elements need consideration:

• Control Medium
• Protocols used in the Medium