New-Fangled Façades

Design and Manufacturing Advancements Take Architectural Glazing to a New Realm

By Ellen Rogers

Shapely, curving and flowing … anything but square—that’s the direction more and more architects are taking their façade designs. Developments in the glazing industry are helping spur many of these new architectural trends and opportunities. Thanks to advances in software and modeling technologies, highly glazed projects around the world are taking on unique formations. But these changes also bring a certain number of challenges, and everyone involved in the project needs to be coordinated to be successful with this futuristic work.

Don’t be a Square

Architectural designs frequently showcase glass and glazing products in new and innovative ways. Attila Arian, president of Schüco USA in Newington, Conn., says this architectural push is driven by the fact that people no longer want to live and work in “fair and square” glass boxes.

“Expression of individuality through architecture has become more popular and, apparently, more affordable,” he says, “so unique designs have become a way to escape uniformity, which is very much supported by the push to-ward urban living. Buildings with glass structures are not only places where people work, but also increasingly live.”

Walter Hartnett, vice president with structural engineer Thornton Tomasetti in New York, agrees that these challenging, geometric forms are in vogue.

“Less repetition, fewer straight lines, and more intriguing, challenging for-mats are testing the limits of our technical capabilities,” he says, explaining that manufacturing capabilities and commercial feasibility feed back into that.

“The focus is on delivering cost-effective, work flow systems that are less repetitive. It’s easier to design a straight façade than one that’s curved, but I think [the trend toward complex structures] has been motivated by the evolving construction standards over the last five to ten years. We have better tools that allow us to design parametrically to capture more complexities in the façade. The end result is you can deliver more intriguing designs with fewer concessions because of cost.”

One project example is the Wilshire Grand Center in Los Angeles, which opened last year. Designed by AC Martin Partners, the skyscraper is home to the 889-room InterContinental Los Angeles Downtown, as well as restaurants and an office complex. It’s the tallest tower in the Western U.S. and features a curved linear curtainwall installed by Benson Industries; Heitmann & Associates was the building enclosure consultant.

“The Wilshire Grand Tower is a building of our time, a contemporary contrast to a past generation of fl at top buildings composed of granite and inset windows long characterizing the skyline of down-town Los Angeles,” says Tammy Jow, principal with AC Martin. “Representing the onset of a new generation, the Wilshire Grand ambitiously employs the use of glass as a modern cladding material for the 73-story tower and its complex forms, geometries and enclosures. A lyrical doubly curved skylight flows through the space between the tower and its solid podium base, within a seismic hot zone.”

According to Jow, the skylight marks the grand entrance to the hotel, provides a central defining architectural element for wayfinding, and is the functional roof of an 80-foot tall atrium.

“Its form is fluid like a river, comprising 430 uniquely sized, rationalized pieces of glass. The skylight’s frame is composed of a truss structure, fixed to the podium, while equipped with slide bearings on the tower side to handle seismic motion.”

Thornton Tomasetti was the structural engineer and established a para-metric façade panelization strategy for the geometrically complex, all-glass façade. The firm synchronized the individual models and complex geometries of the floor slabs and facades, creating comprehensive Revit models to optimize and enhance documentation of facade panelization.

Jow adds, “Imagination has no boundaries. The tools of the profession have become more robust and user-friendly toward creating artful forms. On the Wilshire Grand Tower, our client consistently urged the design team to dream, to seek unique solutions without going over the bleeding edge. We embraced the challenge and selected glass as a primary enclosure material to meet our aesthetic, functional and performance goals.”

Design and Modeling Tools

Advances in digital design and modeling technologies are creating opportunities to design and construct these innovative structures. Parametric design, for example, is one method.

“Parametric design enables designers and architects to create complex geometries and structures. It’s based on the assumption that the parameters defining a design and their interdependencies can be expressed in mathematical algorithms,” says Arian. “This enables the designer to identify and resolve unique conditions and conflicts that would make the building envelope unbuildable due to its complexity.”

Hartnett adds that today’s complex facades involve a level of risk and uncertainty.

“Parametric design allows us to iterate across the platform with multiple variables,” he says. “We’re able to better address the relationship between the design intent and performance requirements to push the envelope on façade geometry.”

Schüco has developed parametric technologies that enable geometric three-dimensional building envelopes to be freely designed. Arian says the company’s parametric facade system combines parametric design with digital fabrication.

“It’s designed to empower fabricators to build and deliver complex geometries and still remain in the confinements of a tested and certified aluminum system,” he says. “Our digital platform called SchuCal reads the parametric design, creates the bill of material and provides the programming for our CNC machines to build these complex structures out of aluminum sticks. The entire process is digital and does not require the creation of fabrication drawings, which reduces the potential for costly errors and con-tributes to the precision and quality of the glazing system.”

Free-form Structures

Parametric modeling and design also enables the development and construction of free-form façades and structures.

“A free-form façade does not have 90-degree angles and corners and the shapes and forms are not straight and square,” Arian explains. “The wavy glass roofs with spherically bent glass (bent in more than one direction) and frames are prime examples of free-form structures. The parametric design enables the design team and glazing contractor/fabricator to design, manage and build these complex structures.”

Hartnett says free-form design is a way of addressing organic/natural shapes in the structure and facades.

“The marriage between parametric design and evolving production techniques (i.e., potential mass customization) has enabled the capacity for complex form-making,” he says. “Now we can deliver free-form facades and other organic structures more affordably. But the real potential is to improve and better guarantee building performance.”

As an example, consider the geometric shape of the Morpheus Hotel in Macau, China, designed by Zaha Hadid Architects (ZHA). The architects de-scribe it as the “world’s first free-form high-rise exoskeleton.” It features a total of 24,577 glass panels, used in a total glazed envelope area of 43,388 square meters and a free-form glazed envelope of 14,300 square meters. (See sidebar on page 75.)

Up for the Challenge?

These complex shapes and structures, however, don’t come easy.

“The cardinal challenge is to de-liver these complex structures at an economical price point. While the demand for complex structures has been increasing, the budgets have remained stagnant or have declined in some regions,” says Arian. “The installation is difficult and puts a lot of pressure on installers and glazing contractors, who are struggling with a shortage of qualified labor. It puts the larger companies at an advantage toward small- and medium-size businesses, so essentially the bigger will get bigger.”

Hartnett says another challenge is knowing the limitations of what’s commercially feasible.

“Our designs need to be fully informed (integrating commercial and manufacturing constraints) for disciplined results,” he says. “We need cost-effective reproducibility of designs for frame-panelized construction, particularly with glass.”

He adds that involving the façade con-tractors early on is a critical component.

“To really drive forward, we need to recognize the interdependency of the design process. Having a model is one thing, but it’s really establishing a plat-form of early engagement … [working with] those who are furnishing and in-stalling the work is critical.”

On the plus side, Arian points out that these projects require the full implementation of digital tools available and promote the integrated or collaborative project delivery methods.

“There is a lot of talk about the construction industry being behind in the digitalization process. This certainly is an opportunity to advance in this area,” he says.

Sweet Dreams: Morpheus Hotel Rises in China

Zaha Hadid Architects’ (ZHA) Morpheus Hotel is the newest tower to take shape in Macau, China. The twisting, geometric façade was designed as a vertical extrusion of its rectangular footprint. It features a series of voids carved through its center to create an urban window connecting the hotel’s interior communal spaces with the city.

ZHA was commissioned to build the hotel in 2012. At that time, foundations were already in place for a condominium tower that did not progress. ZHA’s design is a simple extrusion of the existing abandoned foundations; using this rectangular footprint to define a 40-story building of two internal vertical circulation cores connected at podium and roof levels.The hotel’s design features a pair of towers connected at ground and roof levels. The central atrium in between the towers runs the height of the hotel and is connected with external voids that connect the north and south facades. These free-form voids create the urban window that links the hotel’s interior communal spaces with the city.

According to ZHA, facade engineers Buro Happold International designed approximately 30 different façade systems for various parts of the envelope, all designed to achieve the differing geometrical constraints of façade components such as unitized and stick-built glazing systems, among others. Various panel types included flat, single- and double-glazing, low-E and low-iron glass. These systems also included annealed, heat-strengthened and fully tempered glass.

Because of the logistical challenges to optimize each system and man-age the interfaces between various facades, base geometry of the double-curved “reference surface” was used as the starting point for setting out the glazed envelope and exoskeleton. This was generated with Rhinoceros software, for which ZHA developed a custom T-spine polygonal modelling tool. All the glass panels in the free-form ares are flat. According to ZHA, the core of the design team’s work involved optimizing this to follow the “reference surface” as closely as possible.

Jangho Curtain Wall Macau wasthe façade contractor for the flat area glass system, and Kyotec Hong Kong was responsible for the free-form area glass and exoskeleton cladding. The high-performance glass panels were supplied by Shenbo and coated by Saint-Gobain.

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