The project includes energy upgrading work of the closed gymnasium of the Holy City of Messolonghi, aiming at reducing its energy requirements and saving energy. The project will contribute to the improvement of the building’s energy efficiency and the use of Renewable Energy Sources (RES). More specifically, provision is made for:- Installation of a new Central Air Conditioning Unit (CCI) connected to a heat pump.- Installation of new airway channels. The new system will achieve the heating, cooling and ventilation of the stadium.- Strengthening the electrical installation of the building (new electrical supply, heat pump supply, new lighting lines, replacement of existing lighting with new low energy efficiency lighting (led).- Installation of solar panels and boiler for the production of hot water use.- Installation of photovoltaic system for the production of energy and energy netting.