National Kaohsiung Centre for the Arts, Taiwan

It comes as no surprise to discover that Dutch firm Mecanoo looked to shipbuilding techniques to realise its £258 million National Kaohsiung Centre for the Arts in Taiwan; you could easily fit a supertanker within its vast dimensions. But it turns out those techniques were on tap – Kaohsiung is the island’s third largest city, and a major port. Opening to great fanfare at the end of last year, the centre is sited in the 47ha Weiwuying Metropolitan Park, urban parkland released by the decommissioning of a former military base. The new 14.1ha complex sits at its north east corner, the centrepiece of a huge urban regeneration project. 

And its cultural ambition, it seems, is just as expansive. Keen to be an integral part of the Asian tour circuit of the world’s leading orchestras and opera companies, the city ran an international competition in 2007 for a state-of-the art cultural centre. It eventually plumped for Mecanoo, which was itself taken aback by the scale of the brief. The result is the world’s largest arts and cultural complex to be built in one go – a 2,250-seat opera house, 2,000-seat concert hall, 1,200-seat playhouse, 450-seat recital hall and 800m² gallery space, along with backstage areas, 1,000m² of rehearsal, education and conference spaces, office and administration areas. 

The architect’s response was on appropriately grand scale – the creation of a massive, sweeping, undulating steel roof rising to a height of 38m, that encompasses all the halls beneath it; each space denoted by clearly discernible undulations across its surface. But another key aspect of the winning proposal was the 24-hour covered public space that flows around the five music ‘pods’ and allows fluid connections between the park to the south and public transport and road links to the north and east. On the elevation facing the park, the roof curves down to meet the ground, creating a sizeable outdoor amphitheatre. 

Mecanoo technical director Friso van der Steen explains that the design concept originated from their exploratory visit  to Taiwan before the competition submission. Banyan trees growing wild on the base had dense, protective canopies, and inspired the covered public space that the firm came to call the Banyan Plaza. The group also gained a sense of the Asian aspects it would need to bring to this western cultural typology. ‘In this subtropical climate, the cool of the night allows life to be lived on the street and we wanted that to form part of the brief for the arts centre,’ he explains. ‘It’s hot in the day, and when it rains it pours. The covered plaza is not only shaded and dry but its cross-breeze makes it a few degrees cooler. It’s a space that anyone and everyone can use and puts them close to the cultural events. If they end up buying a ticket to see a show, that’s all for the better,’ he adds.

Yet to merely call the 225m long by 160m deep steel structure a roof would be an oversimplification. Springing from the concrete ground and basement levels, where all the backstage, rehearsal and service areas are housed, the complex steel frame forming the broad arches of the Banyan Plaza supports multiple levels of foyer, restaurant and admin spaces; a programme squeezed into a section that’s in turn covered by the final roof layer covering the whole complex. Bearing in mind the necessary seismic considerations, local engineer Supertech wanted to make use of any structural purchase it could; an idea that Mecanoo, despite aesthetic ambitions, was prepared to run with. The concrete walls of the six pods rising from the base were obvious anchor points for the frame. ‘We had no interest in making the structure any more complex than it was, so allowed as many connections between the frame and pods as we could,’ recalls van der Steen, adding that the design was an iterative BIM process, with drawings passing constantly between the office in Delft and Kaohsiung. 

 

Local shipbuilders’ fabrication of the steel proved revelatory for Mecanoo, keen for a robust structure and skin. Van der Steen found the collaboration inspirational as it involved a change in thinking. At initial meetings, he recalls, he was asked merely for the ‘total weight’ of the building so it could be costed. Then later, the Plaza’s 6mm thick steel wall plates which clad the steel frame were neither needed nor desired to repeat, as shipbuilders are used to cold forming hulls to complex curvatures. Similarly, they were happy for not all the plates’ rear stiffeners to be of the same section. Rather they thicken anywhere they’re being used as fillets for the sprung suspension rods connecting them back to the main steel frame. ‘On a ship any extra deadweight means added fuel costs so any opportunity to minimise this is taken,’ explains van der Steen. And when the architect asked what tolerances they worked to, the reply was, understandably when you think about it, ‘zero’. With hindsight, van der Steen wonders if they should have risen above their own doubts and accepted the shipbuilder’s outlandish offer to fabricate the whole facade and roof out of steel too, adding ‘Never has a ship-building technique been applied on such a large scale in an architectural project. I admired their “can-do” attitude, not least from its sustainability angle.’

Despite the seeming wilfulness of the structure, it for the most part adheres to basic rules, working on a 6m by 6m grid of nodes unless the concrete pod structure precludes it. This mesh of steel supports the foyer floors, allowing vertical circulation to the upper level hall spaces – and ultimately the roof, as it sails over the halls and flytowers.

The final roof layer is complex, having to generate the undulating form, act as an acoustic barrier to the drumming monsoon rain and perform as a waterproof layer. Van der Steen explains that the final layer might only be 1.2mm of aluminium standing seam but beneath it is a 1m layered section of secondary waterproof membrane, bonded calcium silicate tiles to deal with sound, two Rockwool insulation layers,  supports and segmented top-hat section to allow the roof to assume the form of the complex steel structure. There was a thermal insulation component too, to ensure the uppermost steel didn’t expand unduly relative to the more ‘shaded’ structure beneath.

 

Van der Steen states that aluminium sheet roof cladding is not very forgiving of inconsistencies and that, while looking straight in plan, the undulations in the roof meant tapers as the aluminium standing seam ran along its length. Close co-ordination of the 3D roof model with the German roofing contractor was essential. The firm rolled out and cut the 1.2m wide aluminium coil down to a minimum of 400mm as per the BIM model, on site, before hoisting it to the roof for fitting. The contractor was challenged to produce a portion of the roof’s steepest curve before being appointed; the architect has nothing but respect for what it achieved here.

Naturally, rainfall gutters are enormous; here 750mm deep and 500mm wide, repeating at 18m centres over the 35,000m² roof area. This compartmentalisation rapidly transmits the water to a balancing pond via syphonic drainage. With the standing seam roof fixed at the mid-point of the 18m spans, the aluminium can thermally expand and contract into this gutter area. Although the skylights that puncture the roof look random, in fact they nestle within that 6m by 6m structural grid area, requiring only one section of it to be removed.

Taking seven years from breaking ground to commissioning, the project looks to have occupied a substantial chunk of van der Steen’s career. But his take is different: ‘Relatively speaking, it took 18 years to build the Hamburg Philharmonie and Nouvel’s Philharmonie de Paris cost almost €300m. This took far less time and at £258 million is a very cost-effective building,’ he concludes. ‘The city is getting an awful lot of opera house for its money.’