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‘Reuse after done’ is the design motto for a prime venue in the Olympic aquatic sports category
This temporary venue is one of several arenas specially designed to be dismantled and redistributed after the London 2012 Olympic Games. Designed by David Morley Architects (DMA), the Water Polo Arena features a distinctive silver wrap of PVC fabric and an inflatable roof of fabric made from PVC/PE. Seating 5,000, the arena’s parts will be reused elsewhere in the UK and materials put up for rental use in the aftermarket, thus making good on the Olympic Delivery Authority’s (ODA)’s mandate to create sustainable facilities and infrastructure. ODA’s website says “We are creating venues, facilities and infrastructure for the London 2012 Games that leave a lasting social, economic and environmental legacy for London and the UK, while minimizing any other adverse impacts during the design and construction of the Olympic Park, venues, infrastructure and housing.” Fabric Architecture posed several questions to the DMA team and here are its answers:
FA: How was fabric chosen for inclusion as a building material in the final design, versus an alternative material?
The concept for the building is to make it from a kit of parts which can be re-used after the games in a different form on a different site. Some of the components are even used and taken from existing stock in the supply chain. The 54m wide by 124m clear span facility therefore required a lightweight solution to the cladding that would be easily demountable after the games. Hard wall materials were considered but cannot compete with fabric in terms of weight or cost for large span structures. Phthalate-free PVC is a versatile and cost-effective cladding solution. It lends itself to reuse since, unlike other fabrics, it can be folded without creasing, making it easy to bring to site in large panels and then to reuse after the games in other buildings. At the end of the reuse cycle it can be safely recycled through a closed loop recycling scheme where the manufacturer will reconstitute the material into other PVC products. The versatility of PVC meant that the form of the building, evocative of a giant splash made by the adjacent diving figure that the aquatics center represents, could be strongly expressed with a wave like roof and scalloped elevation.
FA: What special design considerations were needed to ensure that the fabric performs up to standards?
As the building is a temporary structure used for short periods of time, it does not need to be insulated. However, a particular design consideration for a water polo venue is to prevent condensation forming on the underside of the roof and eliminate the risk of water dripping onto the pool or the spectators. This problem was solved by having a dual membrane which is air inflated to form huge 54m-long by 10m-wide cushions. This has the benefit of reducing the risk of condensation whilst also being a self-supporting system with no requirement for secondary structure. Each cushion simply spans between 2m-wide structural lighting gantries which are spaced at 12m centers along the length of the building. As phthalate-free PVC is relatively new with a limited track record, further independent structural and fire testing was carried out to ensure the material’s performance. In order to reduce risk of solar gain, the fabric is generally colored with a reflective silver and this also contributes visually to give the venue a distinctive appearance in the Olympic Park. For the competition area the fabric is opaque in order to ensure consistent lighting conditions for high definition TV. Outside of the competition bowl, there are areas of white translucent fabric which will allow daylight in and will glow at night to emphasize the geometry of the seating bowl within.
FA: How does the fabric contribute to the overall functioning of the facility (i.e., performs better than, say, glass in that position within the building)?
The use of phthalate-free PVC has had the following functional benefits:
- Reduced weight of the envelope allows a lighter structure.
- Overall weight reduction has allowed all foundations to be constructed from re-useable screw piles.
- Self-spanning with no need for secondary structures.
- Reflective coating reduces solar gain during the day and provides a canvas for night-time external lighting.
- Inflated cushions provide effective insulation to reduce the risk of condensation.
FA: Was any special detailing developed to secure the fabric in place?
The structure comprises a simple series of portal frames spaced at 12m centers which support on each edge a specially designed extrusion into which the fabric is zipped. The roof panels comprise two layers of membrane which are held in place through inflation. The wall panels are held in place as flat panels held in tension. To avoid excessive deflection, the top section of extrusion is curved, introducing a 3-D curved scalloped effect at the eaves level. The extrusions that form the luff grooves incorporate an additional slot on the outer face which can be used for attaching external features and lighting.