The project concerns the energy upgrade from category D to B according to the Building Energy Efficiency Regulation (KENAK) of the indoor Vonitsa gym, 2.072 m².The interventions that will be implemented include the thermal insulation of the building shell, the change of heating-cooling-ventilation system, the change of hot water production system for use (ZHX) and the change of luminaires.At the end of the work and the completion of the energy consumption, there is expected to be an energy reduction of 47 %.