This project consists of the rehabilitation of an existing building by adding, among other rehabilitation measures, a semi-public green space on the roof with a positive influence on the health of users, positive effects on urban climate against the heat island effect and positive effect on water by it storages in the deck space. It also improves the energy efficiency of the building by the insulation provided by the layers of green cover. Office buildings made for industrial and technological activities, for the new development area in Barcelona, the 22@ area. The area planning required the development of an urban planning that involved the building to meet the requirements of private and public services with innovation criteria, both to the activities developed indoors and to the building image within the city. The joint tries to answers the necessarily regeneration and recycle of buildings and obsolete neighborhoods without the necessity of destroying. Only the structure of the existing building is preserved. The facade is a new skin, double enclosure skin based on bioclimatic criteria for heat contribution and indoors ventilation. The new technological skin expresses the colours, textures and the use of transparencies, therefore the activities involved inside. The roof is projected like a green semi-public space, advisability space. There exists a big hall for multiple uses for conventions, parades and different meetings; a new “level 0” for the coexistence.