Located on Plaza de las Glories Catalanes, the 142 m, 35-storey Agbar tower is a “small skyscraper” that fits perfectly into the acute angle formed by Avenida Diagonal and Carrer Badajoz.
Its shape emulates a fountain at constant, stable pressure – a very suitable image for the headquarters of a water utility. To reinforce this imagery, the building does not stand on the ground floor but springs from a sheet of water at the bottom of a crater-like dip.
Four basement floors fill the whole plot, housing support functions and parking areas. The auditorium in the first basement rises from the ground to blend with the undulated landscaped space around the tower.
The building’s interior core and exterior perimeter are both load-bearing, a design that frees the intervening space of structural columns. Two concrete oval cylinders support a system of metallic beams which in turn supports composite metal/concrete decks.
The floor plan is determined by the building’s eccentric core. A compact area around the lift lobbies gradually broadens out to become unencumbered space for offices and other functions.
The outer wall is composed of an irregular mesh of square modules, giving the impression of a “pixelated” surface. Windows irregularly punctuate the exterior surface, based on calculations of the surfaces’ exposure to direct sunlight. This, together with the point-support grid and flexible office space configuration, give the building its very distinctive appearance. As if by osmosis the external mesh array is repeated internally. The fractal geometry of the outer wall, developed by designers together with Tecno, employs industrial processes that were also used to produce the component elements that fit neatly into the horizontal and vertical curves of the building – a sort of spatial imprinting.
The corrugated aluminium plate cladding - backed by a rockwool layer lying against the outer wall - follows this mesh structure. The outer skin is lacquered in 25 graded colours. From earthy reds at the base, the tower gradually becomes a shimmering blue at the upper storeys, as if seeking to blend with the sky.
The outer cylinder rises straight from the ground up to the 18th floor where it starts to curve gently and gradually inward until the 26th floor. At this point, concrete is no longer used, and the building is topped by a metal and glass dome.
On the last 6 storeys, the different-thickness, post-tensioned, concrete structural floor slabs cantilever out from the central core to occupy the large space under the dome. These areas are earmarked for senior management offices.
The whole building has an outer skin of laminated glass slats of differing degrees of transparency. The result is an intriguing veil blurring the graduated colours of the tower behind. The incline of each specially treated panel is a function of the solar irradiation falling on each wall section.