Bringing ETFE to Southern California

Traditionally, glass has been the material choice for atriums and skylights in buildings as a way to admit natural light.

However, the technology of producing flexible ETFE (Ethylene Tetra Fluoro Ethylene) films has progressed significantly as an alternative to glass in recent years.

Use of the ETFE material began over 25 years ago when many buildings in Europe, particularly in the UK, began to adopt this technology. Lightweight (1% the weight of glass), translucent (transmits 95% of light), and with excellent solar control properties, ETFE is one of the most exciting materials in today’s design industry and is now being widely considered for buildings in Southern California, USA.

Buro Happold has already worked on numerous projects globally using ETFE roof systems, from iconic projects such as the Eden project to the most recent Foster + Partner’s designed Khan Shatyr Entertainment Center in Kazakhastan. Our head office in Bath, UK has developed this expertise and in collaboration with them, the Los Angeles office has now gained the global expertise as well.
Locally, we are applying it to the Anaheim Regional Transportation Intermodal Center in Anaheim, California. This iconic transportation hub, design by HOK Architects and Parsons Brinkerhoff, will serve the future of California’s high-speed rail network. Other projects in Southern California such as Gensler’s Farmer’s Field Stadium in Los Angeles and Miller Hull’s San Ysidro Land Port of Entry in San Diego also incorporate the ETFE cushion system.

The ARTIC ETFE Roof

The unique and dynamic building envelope will feature the largest ETFE roof expanse in North America. The 64,000 sq.ft. ETFE roof is 1/10th the weight of glass, thus allowing for vastly reduced dead load and seismic loads on the supporting steel structure. The ETFE foil roof system also allows the building envelope to respond to varying environmental conditions and the three layers of foil in each cushion, have varying frit patterns to reduce solar heat gain and maximize daylight.

Thermal performance as well as structural performance relies on the air pressure of the ETFE cushions. A detailed structural analysis by our engineering teams in Bath and Los Angeles studied the wind loads and deflections of the diagrid structure and their impact on the stresses in the foils. The connection systems and details are also designed to accommodate high temperature variations in the naturally ventilated building.

The building design’s complex geometry is developed from a unique slice of a developed Torus. The Buro Happold modeling team was charged with helping the architects define the geometry and find solutions for the construction and fabrication of the envelope systems that could conform to the complexities of the geometry. Multiple unique scripts and routines were developed, by Buro Happold’s LA team, to enable smooth workflow between software programs such as Catia, Rhino, Revit and Robot analysis tools. Early modeling of details and components, in Catia and Rhino, helped the various stakeholders to visualize the aesthetics of the system and buy off on the material and technology.