This is a drastic energy upgrade of the 251 General Aviation Hospital which includes sub-projects for the significant upgrade of the heating installations for air-conditioning and hot water production as well as for the significant renovation of its shell and at the same time the production of energy using RES. This operation achieves a thermal energy saving of natural gas of 45 KW and electricity of about 47 KW, which corresponds to significant primary energy savings of more than 45 KW. Also, the quality and reliability of the heating systems for air-conditioning are radically upgraded and an automatic control system is installed for the more efficient operation of the HVAC systems. The HVAC project upgrades the building shell and drastically improves the comfort conditions in all areas.