Energy management, and in particular its optimization, is one of the hot trends in the current days, both at the enterprise level (optimization of whole corporate/government buildings) and single-citizens' homes. The current trend is to provide knowledge about the micro(scopic) energy consumption. In our work we developed a platform, named OPlatform, for smart environments able to micro-account energy consumption of devices, at the level of each single power line, which allows at the same time the actuation of devices, thus being also an energy-aware domotic solution. After presenting the system architecture, consisting of a distributed system based on several OMeters (specifically designed hardware devices) and an OBox (an embedded PC hosting the software system), we present a preliminary case study, in which the OPlatform has been adopted in a small office, in order to highlight the concrete possible savings.