The south side works as a big solar collector that collects the energy and stores the heat. On the north one, the conveyed air pass through the small space between the three glass skin, it is heated and taken to the top, that is where the heat-pumps are placed. Behind the glass panels, some other transparent verandas work as solar collector at the service of every apartament. The entire plant construction of the building is studied in order to create an immediate exchange of heat between the north and the souht part of the structure. The internal garden at the first floor has a unique natural "Air conditioner effect" thanks to this air-flow game. Good insulating materials are used.