The majority of recent developments in BEMS have followed the advances made in computer technology, telecommunications and information technology. In this context, a number of modern techniques and methods have been proposed in the international literature for improving specific systems’ controls. Moreover, a new European standard EN 15232 “Energy performance of buildings – Impact of building automation, control and building management” was developed to support the European Directive on Energy Performance of Buildings (EPBD) (CSN, 2007). EN 15232 specifies methods to assess the impact of building automation and control system, as well as technical building management functions on the energy performance of buildings.