Even the glorious backdrop of one of the world’s favorite cities with the nearby Grouse Mountain can offer no certainty of glorious weather conditions. For this reason, operators at BC Place in Vancouver decided to have its original roof – constructed in 1983 – replaced.
The solution in the form of a retractable roof was provided by Geiger Engineers, and schlaich bergermann and partner, engineers and roof designers in New York. For this project, Geiger Engineers chose SEFAR Architecture TENARA Fabric.
BC Place in Vancouver is a regular venue for international competitions and top-class events. While in the past visitors, players, and other participants were forced to endure hot and humid conditions during the summer months, a way was found using a light, shell-like roof construction to switch from weather-proof safety to an open-air feeling by means of an electronic control system at the touch of a button. Illumination, ventilation, and indoor climate are all noticeably better with the new concept.
A new fixed star has risen
Today, spectators sit beneath a completely new roof construction with a retractable inner roof. In the centre of the cable-supported roof structure lies the pneumatically aided inner roof – one of the largest moveable membrane constructions in the world.
The material used to make the retractable pillows is the flexible SEFAR Architecture TENARA Fabric 4T40HF with a translucence of almost 40%. The 100m × 85m roof opening is the same size as the field below – a playing field in every sense of the word.
Christoph Paech from schlaich bergermann and partner said: "The demands made on the membrane material in a project such as this are extreme. It is essential it possesses sufficient strength, but at the same time it must be sufficiently soft and flexible to withstand the many folding cycles.
"Because of its two-layer pillow construction, the highest possible light transmittance is necessary. Many tests were conducted during the design phase to find the most suitable material."
Falling attendance figures were giving sport event promoters cause for concern and events sometimes had to be can celled owing to insufficient light. The Canadian planners charged Stantec Architecture with finding a material for the two-ply interior ceiling which had to be markedly resistant to water and more translucent than either PVC or fibre glass. The choice of the engineer was SEFAR Architecture TENARA Fabric 4T40HF.
Designed for extremes
In just twenty minutes, the pneumatically supported membrane construction opens from the center outwards to form a roof which keeps out precipitation and bad weather. Once closed, the roof can withstand even a snowstorm and the weight of up to 7000 tons of snow – something not unusual here in British Columbia.
David M. Campbell from Geiger Engineers said: "We decided on TENARA in view of its flexibility and suppleness, but also because of its high translucence. Whether folded or extended, the TENARA roof is a major boost to the entire stadium complex." In comparison to the old construction, energy savings of around 25% can be made; equivalent to around $350,000 annually.
The new roof construction has given the city of Vancouver a new architectural icon and today the reconstructed area of around 45,000m² acts as a magnet for spectators and at night it shines like a glowing beacon. Events are regularly booked out well in advance, able to take place according to a reliable schedule, and considered highlights by those playing here. Before departing for the venue, guests can use Twitter or the BC Place homepage to find out whether the forthcoming event will be open-air, and dress accordingly.