As well as providing striking visual impact, ETFE transmits light like a transparent umbrella and allows for design flexibility, says Simon Higgs, development manager of Structurflex Ltd. Although ETFE membrane structures are lightweight, they can withstand extreme weather conditions. Photo: Structurflex Ltd.

Office workers in Auckland, New Zealand’s Highbrook Business Park can be found most days lingering over lunch or strolling outside at The Crossing, an open-air plaza. The large, open-air green space is home to cafes, bars and retail spaces.

But when the weather doesn’t cooperate, pedestrians able to seize the chance to get outside don’t want to be denied. To keep rain at bay while still allowing for the outdoor stroll or lunch, Structurflex Ltd. of Auckland designed and installed a membrane structure over the courtyard, which makes it user friendly in any weather and is artistically striking all on its own.

The canopies are constructed from ethylene tetrafluoroethylene (ETFE), a lightweight alternative to glass. The transparent, extruded film, from Tokyo, Japan-based Asahi Glass Co. Ltd., offers a light-transmitting ability similar to glass but at just 1 percent of the weight, says Structurflex development manager Simon Higgs.

Every panel of the tensile structure is unique and no two angles are the same. The manufacturing involved had to be precise to ensure the ETFE panels would fit with minimal stretch. Designers worked closely with the project’s architect to ensure the 3-D model of the structure was accurate and to create precise instructions for the steel manufacturer, Higgs says.

The mechanically prestressed support structure is strung with ETFE and pneumatically prestressed, pillow-like ETFE cushions. The system boasts a lifespan of more than 25 years, which is good, because The Crossing is moving into stage two. This means an expansion to five buildings, the tallest of which will rise to nine stories. Its open-air plaza, shaded entertainment areas, retail spaces and other accommodations will still serve as the focal point for the area’s growing community, who can dine and take outdoor breaks under the ETFE artwork-like installation, rain or shine.