Building automations are a fundamental part of the energy management systems. For the purpose of this paper the building automation system that was used is the Dupline system. The decentralized building automation system Dupline combines heat, lighting, A/C and other building monitoring procedures providing high standards of comfort, security and energy saving potential. Compared to a traditional installation the wiring of a Dupline system is much simpler and the flexibility of change and expansion is significantly increased. Furthermore, the automation system Dupline can transmit multiple digital and analog signals over long distances by the use of a standard 2-wire cable. All the other units of an installation, such as input–output (I/O) units, energy meters and sensors are connected through the pair of wires to master generator, which processes the signals coming from the various bus networks.