SmartGrids are conceived as modular, end-to-end interoperable systems. It is envisaged that power systems components (modules) will be hierarchically coordinated and integrated in order to form certain autonomous clusters which would perform as much as possible local data storing and processing in order to decrease overall communicational and computational overhead. Building Management Systems (BMS) could be seen as one of such modules inside wider SmartGrid system. The incorporation of BMS must consider both technical as well as commercial issues. Hence, the efficient integration will require standards'' harmonization and closer interaction among key elements of these systems. Moreover, another important issue will be adopting of new market models to BMS. In order to represent the system and relations among its components in a clear and understandable fashion, we introduce system level modeling concept as an instrument to bridge functional requirements and implementation constraints.