The paper deals with energy efficiency measures for music school “Luka Sorko?evi?” in Dubrovnik. The protected building situated in the old part of the city occupies the sites of two former nunneries. Up today electric resistance heating with radiators in heated space has been applied. Hourly simulations of all year round energy consumption of the building have been performed in order to define optimal replacement system. High temperature heat pump combined with existing electric boiler has been analyzed, as well as replacement of radiator heating system with variable refrigerant flow heat pump system. Variable refrigerant flow heat pump system which gives high level of the comfort has been chosen, giving lowest energy costs as well the lowest CO2 emissions compared to other systems including conventional gas or oil heating as well. Other energy efficiency measures comprise window sealing, lighting improvements by introduction of CFL and introduction of saving mode for office equipment. Total effects of proposed measures result in CO2 emission decrease of 75,8 tons annually compared to present state, and the investment payoff time of approximately 5,6 years.