Comparative Study of Different Scenarios for Ensuring the Energy Performance of an Existing Building

The recent legislative changes concerning the energy efficiency of buildings make it compulsory that high-performance solutions are considered for both buildings envelope and its technical system. While the new construction rate of the non-residential sector has been consistently high during the last decade, also rehabilitation works on existing buildings have been done, involving both expansions and energy efficiency works, as there are different sources of financing available to support the reduction the energy consumptions. When increasing energy efficiency of buildings both thermal rehabilitation works on the envelope and improvements on the efficiency of the technical system are needed. Thermal rehabilitation works will increase the thermal resistance of the enclosing elements, reduce heat losses, limit thermal bridges and air infiltrations. This paper presents a non-residential building, located in the IVth climate zone of Romania, for which a consistent expansion was needed in order to accommodate a larger number of occupants and, at the same time to comply with the current essential requirements. Thus, several scenarios were considered, which integrated renewable energy sources. The compliance with the performance indicators imposed by the new legislation in the field was analysed. The simulations were carried out in a dedicated software, and the results obtained were analyzed in terms of primary energy consumption and equivalent CO2 emissions.