The Serpentine Gallery's architecture pavilion programme likes nothing better than a challenge, and its biggest challenge is one-upping itself. After convincing a reluctant Oscar Niemeyer to participate in 2003, two years later the gallery turned to Dutch practice MVRDV who proposed, rather than a separate pavilion, to roll a lawn up and over the gallery itself. This proved ambitious even for the Serpentine, so lvaro Siza and Eduardo Souto de Moura stepped in to the breach with a spider-like timber structure in 2005. This year, OMA in collaboration with Arup, which has participated in the pavilion programme since 2001, has proposed an ephemeral 'non-pavilion': a translucent inatable roof canopy which oats over polycarbonate walls with no apparent structure.
The enclosed area of about 350m 2 houses the usual café and exible seating which can accommodate up to 300 people for evening programmes. In good weather, the roof can be raised 4m above the walls. The balloon's height, which is 24m when open, is taller than the gallery roof.
Arup associate Tristan Simmonds, of Cecil Balmond's Advanced Geometries Unit, a veteran of Anish Kapoor's red Marsyas in the Tate Modern's Turbine Hall, describes this year's pavilion as 'extremely complicated'. Almost every detail is bespoke and, as always with the Serpentine pavilions, the telescopic time frame requires the designers to double as project managers during construction to make it all happen. There is no time for trials and mock-ups, so the design team has to go with its best guestimates of what will or will not work. With a movable inatable structure which is responsive to wind and weather conditions, there are even more than the usual number of variables.
To understand the technology of balloons and airships, Arup went to Lindstrand Balloons, collaborator of Richard Branson. But, of course, OMA's balloon is no ordinary balloon.
Not only is it asymmetrical, but it is also not designed to y, so that most balloon data which is based on stratospheric conditions, is irrelevant. Responding to a nearby tree on the site, OMA gave the balloon a dimple. The final form of the balloon, according to Simmonds, is partly sculpted and partly 'found form'. Starting with OMA's abstract architectural form, Arup developed 3D software called 'nip and tuck', which incorporates the stiffness and tensile properties of the balloon fabric and manipulates them to find forms that do not exceed the strength of the fabric and are sufficiently resistant to the wind. In the early stages, OMA was looking for a more spiky, Sonic the Hedgehog form, explains Simmonds, but this proved difficult to achieve. The final form is more mystical, reecting Balmond's inuence.