David Chipperfield and b720’s City of Justice in Barcelona is legible at every scale, from site plan to detail design, says Rory Olcayto. Photography by Christian Richters
Imagine a chunk of city, more than a third of one million square metres, made from a single cast concrete detail; a district of nine towers up to 14 storeys tall, defined by nearly 12,000 iterations of the same structural module. These are the numbers behind David Chipperfield Architects’ biggest project to date, the City of Justice, which brings together all of Barcelona’s legal services in one complex.
The scheme, completed in partnership with local practice b720, has an elemental simplicity, easily read at any scale. In terms of the city, it fills a gap site that marks the boundary between Barcelona and neighbouring municipality L’Hospitalet de Llobregat. In terms of site, the City of Justice creates its own condition of solid and void; tower blocks arranged around and off a concourse and plaza, rather than keyed into the flimsy arrangements that form the immediate context. Project director Andrew Phillips calls it ‘a city within a city’.
The huge concourse is a building in itself: four storeys of concrete floorplates that step back along the western edge, held up by a field of cylindrical concrete columns. Each block is a cuboid formed of that same cast-concrete, fair-faced detail. Every elevation is identical. Each building, however, is a different colour and has its own height and width.
Here we present Chipperfield’s City of Justice at these varying scales: from site to circulation, and from individual block to window detail.
In February 2002, David Chipperfield Architects won an invited competition to design the City of Justice for the governments of Barcelona and L’Hospitalet de Llobregat. At the time, various legal departments occupied 17 buildings scattered across the two cities. A site previously used as military barracks, on the boundary of the two authorities, was identified for development. The idea was to create one huge complex where every legal transaction would be processed, from dog licenses to criminal prosecutions.
Chipperfield’s solution was to break down the programme into a city quarter comprised of individual blocks. ‘Logistically it’s very sensible,’ says Phillips, ‘but symbolically, it’s part of a bigger process to clarify justice, to literally tidy it up and say “justice is here”.’ Initially, the City of Justice brief specified 11 individual blocks to be spread across the site. However a change in government in 2004 required the architects to rework the brief and consolidate accomodation into nine blocks, despite having completed all working drawings.
On the site’s eastern flank, four free-standing blocks – judicial buildings, with four floors of courtrooms and offices – hang off a central concourse. To the west, others lie adjacent but adrift to the concourse, creating an external plaza filled with trees. These solitary buildings include a judicial services block for L’Hospitalet, a forensic sciences centre and two commercial blocks with retail facilities at ground floor. A social housing block is under construction. ‘One of the reasons we defined the site with a dynamic series of boxes is because there was nothing around to get our teeth into,’ explains Phillips. He calls the composition ‘a still-life of blocks placed on a tabula rasa’.
The dynamic arrangement creates narrow crevices between each block, which Phillips says offsets the potential for alienation that such a large, single-note scheme could induce.
Most of the concourse’s western elevation – mesh screens placed in front of frameless glazing – is open to the external plaza as a result of the project being scaled back. Two further blocks, which would have almost entirely enclosed the four-storey concourse, were cut from the brief. Consequently, the plan of the concourse changed. Arms, originally extending westwards and feeding the now-excised blocks, were amputated, and a vast skylight supported on concrete beams was also ditched.
More than 12,000 people traverse the concourse every day. While the accused enter courtrooms directly from basement cells in each building, and judges and witnesses from underground car parks, entrances at either end of the concourse filter citizens and staff. Staircases and escalators link each floor. ‘It’s a very simple building. There’s no programme except walking around,’ explains Phillips.
City of Justice in numbers
Number of windows 11,666
Amount of concrete used 96,500m³ Overall 9,500m³ on the facades
Original square metre count for total project 288,700.5m²
Number of architects/assistant architects on the project 130 (DCA and b720)
Number of project drawings 10,000 in the ejecutivo stage (RIBA Stages E, F and G)
Number of days spent on the entire project 3,677
Number of contractors Five companies formed UTE Ciutat de la Justicia – 1,200 individual workers were on site over the period of construction
Number of cranes on site 14
The concourse’s construction detail is simple too, low-tech even, mostly crafted from white concrete. A field of 500mm cylindrical columns support concrete slabs with exposed fair-faced ceilings, lined with perforated metal acoustic panels. The surface of the raised floors, under which ventilation borrowed from the judicial blocks flows, is 1,200 x 400mm red terrazzo tiles. Where the slabs step back, terrazzo continues under the glazed and mesh elevation to form one continuous flat deck. ‘It’s a very basic section,’ says Phillips of the drawing shown on the opposite page, ‘But that was the whole point. There are not too many details involved.’
The height and width of every block in the City of Justice is determined by its programme. There is no leftover space.
Each judicial block (with the exception of the building for L’Hospitalet, which contains courtrooms and offices) locks directly into the concourse. A concrete core, with a central entrance and lobby at the concourse end of the block, houses fire escapes and lifts to transport workers to the offices above.
To reach the courtrooms, the public moves through corridors along the perimeter of each block. Courtroom staff access a central service corridor from a lift and stair core at the east end, while the accused enter from lifts set between them. The forecourts of each block are lined with granite tiles, and the courtrooms have a terrazzo finish to match the concourse. ‘Technically, these buildings are machines,’ says Phillips. ‘They have to work with utmost efficiency.’
Each block is constructed from cast in-situ, loadbearing coloured-concrete cage facades. In the early phases of the project, David Chipperfield said to Phillips: ‘Once that cage detail is resolved, the entire scheme is done.’
The concrete cage detail, which incorporates a double-glazed openable window, is repeated 11,666 times across the nine blocks. Windows are 600mm-wide, although each facade has two 700mm-wide vertical strips for fire access.
At one point there were 12 cranes and seven concrete contractors on site. ‘Normally, with buildings of this size, you see the frame go up and then you’d wait for the facade for months. But here, as the structure went up, the facade emerged,’ says Phillips. ‘You couldn’t make the next floor until the loadbearing facade below was in place.’
The facades comprise panels of six bays of windows and pillars made with stainless steel formwork. Each storey was formed and poured over two weeks, with the facade looped around the floor slab. Less than 50 per cent of the elevations are glazed, but light still streams in. The 250mm-deep reveals, meanwhile, provide good solar shading. ‘Up close there is a solidity and strong materiality, but further away, the elevations resemble a weave,’ says Phillips, which brings us to the mesh weave that lines the concourse’s frameless glazed facade.
The mesh screens
The mesh screens are at odds with the weighty kit of parts that makes up the City of Justice – a clue, perhaps, that this detail emerged after the brief was scaled back. A bespoke product, they were sourced from a local firm which produces stainless steel conveyor belts for bakery ovens. Formed from a series of hooks that clutch horizontal bars, the screens provide 50 per cent shading. A custom detail keeps the screens taught and flush externally.
These are among the smallest components of Chipperfield’s project, and they have a delicacy that belies the monumental first impression given by the City of Justice.
Tender date February 2002
Start on site date July 2004
Contract duration 58 months
Gross external floor area 241,520m²
Form of contract PFI type procurement with design and build
Total cost 240 million euros (£200 million)
Cost per m² 1,000 euros (£850)
Client Ministry of Justice/GISA, Departament de Justicia (Generalitat de Catalunya)
Architect David Chipperfield Architects/b720
Structural engineer Jane Wernick Associates
Services engineer Arup
Quantity surveyor Tècnics G3/Tim Gatehouse Associates
Main contractor UTE Ciutat de la Justicia
Annual CO2 emissions Uncalculated