At this waterfront congress centre, Selgas Cano’s adept handling of overlaid translucent planes elevates cheap materials into a rich experience
Last March, when Queen Sofía inaugurated the Batel Auditorium and Congress Centre in Cartagena, Spain, the moiré patterns thrown off by the thin stripes of her suit played a nice riff against the backlit translucent plastic walls and lime-white rubber floors of the building. In fact, everyone looked terrific strolling up and down the long entry ramp to the concert hall. Like the expanse of stone that spreads out before Philip II’s monastery-palace at El Escorial, or the sandy walks in Madrid’s Retiro Park, the building’s luminous, abstract surfaces put everyone on stage, transforming their moving figures into a stately pop ballet.
The building, designed by José Selgas and Lucia Cano of the Selgas Cano studio in Madrid, extends for 210m along the former mercantile wharf of the port, and is itself conceived as a promenade. It terminates the larger promenade that stretches for 1,000m along the waterfront, incorporating restaurants, cafés, a yacht club and the National Museum of Underwater Archaeology, designed by Seville-based architect Guillermo Vázquez Consuegra and opened in 2008. Together with Rafael Moneo’s restoration of the Roman Theatre (AR February 2009), located on the hill behind the wharf and also opened in 2008, these works form part of an effort to attract tourism and redevelopment to this ancient city and naval base, founded by the Carthaginians in 227BC.
From outside, the building resembles an industrial assembly line of unadorned volumes in different sizes, interrupted by abrupt vertical cuts that throw natural light into transitional interior spaces. The volumes are finished with great simplicity and evident economy in repeating profiles that, were they not translucent and glowing with LEDs from within, would differ little from conventional industrial-grade corrugated siding (the cost of the 18,500sqm building was €34.5 million).
Selgas Cano designed just three custom extrusions that clad virtually every vertical wall. For backlit and translucent surfaces, they designed a wide clapboard-like element with fitted edges along its length and a slightly peaked profile (like an open hand, says Selgas), which is made of Plexiglas on the exteriors (to block UV radiation) and polycarbonate inside (for its fire resistance). The extrusion has an uneven ribbed back to break up light and blur images and imperfections. It is tinted in various tones, including solid white for opaque backlit walls, and aquatic blue for the main auditorium, where it is backed by mirrored film to set off shimmering reflections. Three beads of accent colours, each six microns wide, are laid into the translucent elements (phosphorescent oranges, yellows, blues, greens).
The short end walls of the exterior are clad with a screen of irregularly-placed vertical aluminium fins, with an asymmetrical triangular section (one face is curved and two are straight). The Madrid street artist SpY designed a vivid colour scheme for the entry facade screen, which has a double reading depending on your direction of approach (left or right). It is emblazoned with a supergraphic ‘B’, the architects’ preferred name for the complex, which comes from the Batel Beach that lies beneath the wharf. The roof, visible from the heights behind the building, is also of aluminium.
Opaque sections of the exterior, including the stage house and parts of the auditorium, are screened with translucent horizontal piping, also streaked with dyes and lit up inside. The pipes overlap in a deep, irregular section, and are held in place with a surprisingly simple hooped clip. For the large terraces of the restaurant and exhibition hall on the upper floor, this piping runs horizontally as a sun screen.
Entering at the head of the linear building, visitors are slowly immersed in a world of light, colour and reflections, drawing them more than 100m down the main ramp towards the 1,500-seat auditorium, which is located 15m below ground to minimise its exterior volume. Along the way they filter around a bright-red suspended ramp that ascends to the exhibition hall, and pass orange gashes in the backlit walls that house the information desk and ambigú (the intermission bar), zigzagging benches and a clear plastic bubble chair by Eero Aarnio that is suspended under the ramp (hello, Barbarella).
A run of meeting rooms steps down parallel to the ramp, in a sequence ending with a smaller auditorium seating 500. On the floor above, the restaurant and cafeteria, with interiors by the architects, feature an assortment of classic 1960s pedestal chairs by Eero Saarinen, Pierre Paulin, Eero Aarnio and Verner Panton, arranged around the architects’ wire-leg tables. The wire chairs on the terrace are by Junya Ishigami. In these spaces and the adjacent exhibition hall, long gashes in the ceilings admit natural light.
The long descent to the main auditorium comes to a climax in a soaring vestibule, enclosing the accessways to the two upper seating decks. A maze of suspended stairs and balconies, crafted in nautical white-painted steel, face off across the narrow chasm against a wall of orange-coloured ETFE that catches fiery light from the evening sun. Measuring 28x12m, the wall is the largest continuous ETFE cushion ever made, according to structural engineer José Romo, and is unique in its flatness, achieved by running vertical tension cables through it at regular intervals.
After the hot glow of this interlude, the cool aquatic wash of the auditorium has a big sensorial impact. Curtains inside the walls can open to flood the space with daylight, while another EFTE clerestory over the stage tints the head of the sloping polycarbonate ceiling in contrasting orange at sunset. Acoustic engineer Higini Arau, who also worked on Selgas Cano’s 2006 polycarbonate-lined auditorium in Badajoz, claims that the acoustic performance is close to perfect, with ‘a response to low frequencies as good as the finest wood’.
Backstage spaces are independently accessed from the exterior via a winding ramp, which is covered in a colourful arching canopy. Mechanical services, with their louvres and vents, are cleverly concealed here. Site furnishings include wooden decking with inexpensive outdoor lighting on ‘wilted’ stems (the curve in the post allowed for a slimmer section, explains Selgas), and breakwater stones dredged up during the site excavation, which serve as sculptural benches.
The straightforward massing and simple, ingenious detailing of Selgas Cano’s building belongs to a Spanish tradition of low-tech functional design that can be traced back to Alejandro de la Sota’s work in the 1950s and ’60s, and to the early minimalist work of Ábalos and Herreros in the 1990s. Lately, architects like Selgas Cano have reinvigorated this tradition not only with the latest technical innovations such as ETFE, but also by drawing on the industries that serve the thousands of hectares of plastic-sheet greenhouses in southern Spain. And unlike many of their predecessors, Selgas Cano take realism and solemnity out of low-cost tech − its overtones of deprivation or asceticism − and approach it instead as a liberating opportunity for playful invention.
At a deeper level, Selgas Cano’s design defines architectural play in terms of registering light and colour planes in space and movement. And in essence, like the spreading plaza of El Escorial, these abstract qualities have much to do with the wide-open, treeless plains of the archetypal Spanish landscape. The architects themselves make a similar point: ‘This long construction feeds on the heritage of its site: the immaculate straightness of the pier edge (straight), the invariably calm sea (flat), the artificially horizontal plane of the dock (flat), and the sky as a variable background to this plane (plane on plane).’