The operation concerns the energy upgrade of the building where the 2nd Gymnasium of Giannitsa is housed The building is particularly energy-intensive and requires interventions for its proper environmental and economic operation aiming at the minimum energy needs throughout the year and to meet these needs with the most efficient system possible The planned interventions are the following: Addition of thermal insulation of the shell to the exterior walls and the roof of the building Replacement of old frames with new double glazing Insulation of the heating pipes Replacement of the heating network Replacement of the existing circulators of the heating network with Inverter circulators Addition of thermostatic valves to the heating radiators Replacement of the lighting fixtures with new modern LED technology Addition of artificial lighting control systems Replacement of air conditioning units with new modern technology Installation of a photovoltaic system with net metering of produced and consumed energy