The thesis discusses Vila Bled which currently operates as a four-star hotel. The facility only operates during warmer months due to its high heating costs as a result of its energetic inefficiency. In addition, the building is protected due to having cultural heritage and therefore, some limitations about renovation measures must be considered. Relevant legislation in the energy sector is presented, the restrictions that apply due to its cultural heritage protection, and the proposals based on pre-made studies of the building. The current state is also analysed, its energy balance, calculation of insolation and adequacy of building's envelope. It was assessed that the current situation exceeds the criteria given in Rules on efficient use of energy in buildings five times over. Based on the limitations of cultural heritage, protection proposals are given that would be feasible. The present proposals are: replacing windows, additional roof insulation, and replacement of energy source for heating with a wood chip furnace or heat pump water. These suggestions are taken into account in the assessment of the energy balance of the building and compared with each other. At the end of the thesis, it is suggested which of the pending proposals would be most effective, namely the simultaneous replacement of windows by selecting the appropriate glazing, additional roof insulation, and replacing energy source for heating with biomass. It is estimated that the annual energy required for heating is still not sufficient by the criteria given in Rules on efficient use of energy in buildings, but it would improve the current situation by 22 %.