The project concerns the upgrading of the energy efficiency of the Municipal Hall of Katerini to a category of at least A+ of the Buildings Regulation (KENAK) and saving a percentage of primary energy of more than 89 %. The aim is to transform a building that operates at great cost, into a low-consumption building that meets all the specifications of a modern building, as well as the precursor to the upgrading and other buildings of the Municipality. To this end, the following measures shall be provided: — Thermal insulation of the vertical building elements of the building, floors and roof. — Replacement of windows and windows with new certified, low thermal permeability. — Installation of moving shades on the south, east and west sides of the building. VRV (Variable Refrigerant Volume) or VRF (Variable Refrigerant Flow) cooling system. — Installation in the room of the VRV external air-conditioning unit building, low noise combined with corresponding indoor units in the office spaces. Installation of ventilation systems with heat recovery of at least 73 % and inclination of incoming air. — Installation of LED tech luminaires, drastically reducing the electrical power consumed in the building. Installation of a central building management and control system (BMS, KNX, etc.). — Installation of photovoltaic panels on the rooftop of the building, with south orientation, total surface of about 150 sqm and a power of 23 kW.