The proposed Act concerns the energy upgrading of the building complex of the Polygyros High School of the municipality of Polygyros The school complex consists of 2 buildings The energy inspection of the buildings of the complex showed that the energy consumption of the buildings is significant The buildings were classified as energy during its energy inspections in category H The study proposes the interventions for the energy upgrading of the buildings These include interventions in the building envelope change of the thermal insulation of the facades and ceiling modification of the heating installation of the complex application of a hybrid system with boiler and air heat pump replacement boiler replacement of non-functional heating bodies installation of photovoltaic system and interconnection of the PPC for energy compensation replacement of lighting bodies and installation of an automatic heating control system.