Torre Agbar in Barcelona

This 142-metre-high headquarters of a water-supply undertaking was designed like a “fluid mass that shoots out of the ground under constant pressure”, avoiding the strict verticality of most skyscrapers and at the same time reflecting the link with water. In an interplay of light, transparency and colour, the multi-layer facade lends the building a diffuse, vibrant quality. A load-bearing concrete outer wall, punctuated by 4,500 window openings in an irregular arrangement, provides a good thermal shield. The wall is clad on the outside with coloured aluminium sheeting, and 90 cm in front of this is a layer of more than 56,000 glass louvres that can be inclined at various angles. The blue and red colours that shimmer through this skin become increasingly subdued towards the top, eventually turning to white and finally giving way to a fully glazed dome. The space between the facade layers forms a thermal buffer and allows a natural circulation of air and ventilation. Loads are borne by a concrete core and – up to the 25th floor – by the outer wall, which tapers upwards from 50 to 30 cm in thickness. The inner concrete core accommodates lift shafts and service runs. By locating the core off-centre, it was possible to create large continuous floor areas. On 28 of the 34 upper storeys are offices, which can be flexibly divided with glass partitions. One floor houses a cafeteria; another is foreseen for changing uses; and three storeys are devoted to mechanical services. Parking areas and spaces for various events and activities, such as an auditorium with seating for 350 people, are located underground.