Sanjeev Tankha, Facades Group at Buro Happold West Coast
In an era defined by a need to do more with less, new approaches to facade design offer an optimistic counterpoint to tight construction budgets and climate change. As advances in computational design and analysis enable greater integration between building components, facade design has shifted focus from aesthetics and waterproofing to a pursuit of optimal building performance that encompasses design intent, structural efficiency, interior comfort, and energy performance. Most critically, this systems approach allows for a win-win scenario—vastly improved performance while controlling costs. Lessons learned from recent projects suggest that taking these innovations to the next level will demand a concurrent re-conceiving of traditional boundaries between disciplines.
The future today. Envisioned as a symbol of California’ leadership, the Anaheim Regional Transportation Intermodal Center (ARTIC) will serve regional transit lines including Amtrak, Metrolink, Greyhound and OCTA as well as the state’s future high-speed rail network. Undertaken in 2009, a time of heightened public scrutiny of project budgets, the $184m, 67,000 sq ft project demanded some new thinking, tools and technologies.
The complex geometry of ARTIC’s enclosure establishes the public facility’s iconic resonance, but it also composes a large percentage of the construction cost, making it imperative that the facade achieve levels of efficiency not possible through conventional design processes. Facade design used to prioritize structural efficiency; giving environmental performance equal weight forced new considerations and a new parameter for optimization.
Based on initial analysis, the design team led by HOK zeroed in on a three-part enclosure system composed of a structural glass high transparency wall, metal rain screen system, and ETFE roof cladding system, a light-weight, translucent fluorine-based insulating polymer. The facade team developed 14 unique scripts and routings to enable interoperability between software programs. This integration allowed the team to model for architectural visualization, material structural analysis, energy and daylight simulation, lighting simulation, geometric rationalization, clash coordination, cost estimation, digital fabrication and construction sequencing. Because ETFE’s thermal and structural performance relies on the air pressure of its cushions, the integrated modeling was crucial to gaining approval of its use, especially given its unprecedented scale for North America.
While familiar in Europe, use of ETFE remains relatively uncommon in United States, making it a more challenging choice from a building codes, cost and constructability point of view. But when evaluated in concert with structural and MEP systems, ETFE had clear advantages, especially given the cost premium of meeting California’s heightened seismic requirements. It’s three layers of foil with varied frit patterns maximize daylight while reducing solar heat gain, while its ultra-light weight – just one-tenth that of glass – greatly reduced dead loads on the supporting steel structure.
The modeling also included the building’s ongoing operation. ARTIC’s two high-transparency, glass curtain walls, soaring to 120 feet high at the North end, feature operable glass louvers controlled by a central building maintenance system to provide natural ventilation for the large atrium space.
A scalable approach. While critical for large-scale complex structures, the advantages of an integrated systems approach to facade design applies at all scales. For the Manhattan Beach Library designed by Johnson Favaro, collaboration across disciplines and structural glass analysis in ROBOT made possible an elegant, high-performance double glazed wall, completely transforming the symbolic presence of this new 20,000 sq ft public building.
While Europe has shown that higher performance standards can drive innovation in building technologies, we have proven that a holistic analysis that considers building systems, design and cost simultaneously can rationalize bolder measures regardless. So why wait?
Sanjeev Tankha leads the façades group for Buro Happold West Coast and was a key member of the design team for ARTIC. An architect who has specialized in facade design for nearly 20 years, he has led research and development of high-performance building envelopes for projects worldwide.