Intention of this work is to investigate the opportunity and feasibility of more energy efficient networking in wired Home and Building Automation Systems, which have traditionally devoted a relatively little attention to this issue, especially if compared to wireless networks. This paper will propose a solution to address the problem by evaluating the introduction of power state switching in a real scenario and defining the concept of functional and spatial adjacency among packets. The impact of adopting such approach will be assessed through a simulation aimed at determining the best trade-off between energy and Quality of Service.