The project concerns the energy upgrading of the enclosed Gymnasium “ATHLION” of the Municipality of Andravida-Kyllini in the Region of Western Greece and the improvement of its energy classification in category B according to the Energy Efficiency Regulation (KENAK).To achieve this objective, the following tasks are provided: a) Works in the building shell: Thermal facade on the exterior walls, replacement of the metal roof with new thermal insulation panels, replacement of windows and windows with new aluminum with thermal interruption and double, thermal insulation, soundproofing and reflective glass panes, thermal insulation and water insulation of the surfaces of the rooms.b) Upgrading of electromechanical installations and surrounding space: Installation of a central air-conditioning unit for heating, cooling and ventilation, installation of thermal solar system, installation of split air conditioners in the auxiliary areas, replacement of lamps and LEDs, installation of an energy netting system, autonomous photovoltaic lighting and tree planting.