Growing Panes

Growing Panes

As architects push for never-before-seen designs at ever-lower prices, they are learning that some risks don’t pay off. When they do, however, the results achieve a brilliant crystallization of glazing art and science.

Last spring, the Port Authority of New York and New Jersey shattered a dream when it dropped SOM’s plan to clad the base of One World Trade Center in prismatic glass. The design element was meant to emanate “splays of color” from the building’s podium, but after several years and nearly $10 million spent on design development, the team found itself without a viable sample. It had paid to build specialized equipment to cut 1-inch-thick, 48-by-159-inch glass panels with a grooved, pointed pattern, then temper the prismatic sheets and laminate them to strong barrier glass.


The project was going to be an exemplar of architecture’s best hopes for the future of glass: huge panels with a highly customized, carefully fabricated visual quality that could meet strict safety requirements. But during impact testing, the panels broke into large shards rather than holding together as laminated glass should. The team finally announced the design was too technically difficult to realize.

Or was it? Nathan Munz, managing director of Australia-based glass fabricator Glassform, said that he manufactured a sample of viable prismatic facade glass after being contacted in May 2010 by a project manager with Solera/DCM, the contractor charged with installation of the podium facade. According to Munz, Glassform made the list of approved fabricators for the project, along with Ontario-based Barber Glass Industries, before Solera’s fabrication subcontractor, Las Vegas-based Zetian Systems, gave the fabrication work to Sanxin Glass in Shenzen, China. Barber, too, was contacted in March 2011 about getting back on board with the project; the company had developed a full-scale mockup for the project in 2009, before going into receivership last year.

When it seemed as if option A had failed, the team “started getting worried because they had a project to deliver and the Chinese friends were not supplying even small samples,” said Munz. “They started calling people to see if there was an option B.” Glassform developed a sample without accepting fees and sent it to New York the following month. “I had meetings with Solera and their engineers and they were impressed,” Munz said. But he left confused after Tishman, the project’s construction manager, declined to meet or to sign a confidentiality agreement about his fabrication techniques.


Munz returned to New York in October 2010 with a larger 4-by-2-foot sample, this one protected by an application for a U.S. patent and manufactured with equipment “modified in a very unconventional way.” He brought the sample to a meeting with project manager Ken Lewis and several other SOM team members. “The sun was streaming through the window and it hit the glass and these people freaked, absolutely freaked,” remembered Munz. “They said it was amazing.” But after Tishman again declined to meet with him, Munz was left to conclude that the construction manager had already decided to abandon the project unless it could be realized with Zetian. When contacted by AN a spokesperson for Tishman declined to comment about the project’s glass.

Somewhere in a Pennsylvania warehouse, hundreds of PPG Starphire glass panels that the Port Authority purchased for the project will never see the light of day, but other buildings may soon realize what One World Trade did not. Glassform expects to release a new mass-produced prismatic architectural glass product to the market by the first quarter of 2012. (In early November a new scheme was announced for the building’s base featuring back-lit glass louvers set at angles.)

In spite of the trial and error involved in testing new designs, architects are determined to push the limits of glass technology. In most cases, innovation is more easily achieved in Europe where building teams are likely to negotiate a way to use the best product rather than incorporate more of a lower-priced option. The proximity of several glass-producing nations also fosters an adapt-or-die mentality: Italy depends on exporting its products to France and Germany, forcing them to advance their industry quickly in order to compete with domestic fabricators in those countries.


Reykjavik’s new Harpa Concert Hall and Conference Center is a prismatic addition to the city’s waterfront and a glamorous example of collaboration rather than compromise. Designed by artist Olafur Eliasson with Henning Larsen Architects, the 301,000-square-foot building’s south face is composed of 823 “quasi bricks” mimicking crystallized basalt columns commonly found in Iceland. Each brick is a stackable, twelve-sided module of steel and glass that Eliasson and his structural engineers designed using several digital and physical modeling techniques. The north, east, and west facades are flat variations of the south face, as if the bricks have been sliced at an angle. Ten types of glass were used for the skin: yellow, green, and orange dichroic panes reflect their complementary colors, blue, red, and purple; clear, antireflective, and five kinds of reflective glass are also layered carefully to alternately emphasize depth, solidity, or transparency at different vantage points and light levels. At night, the facade glows with more than 700 LED strips with optics developed with lighting manufacturer Zumtobel. “It has been a process pretty much like doing a painting,” said Eliasson in a project presentation video. “When you have the colored glass that has a tendency to stand out, I have put a low-reflection glass next to it in order to give you a sense of it being a volume.” The hall’s foyer, balconies, and ceiling are oriented to catch light and color. The facade functions, too, standing up to Reykjavik’s punishing winter winds and preventing noise from a nearby highway from disturbing concerts inside.


As advancing digital modeling and engineering capabilities allow integration of cutting-edge shapes and sizes, technical material advances are also driving new designs. David Chipperfield’s Two Lines pavilion was one of this year’s London Design Festival Size + Matter commissions pairing designers with materials and manufacturing processes. Chipperfield created the installation with 28 panes of unframed laminated glass panels embedded with SEFAR Architecture Vision and a DuPont SentryGlas interlayer, a new fabric with a translucent single-sided metal coating. Built in collaboration with Arup, the project’s orthogonal glass walls in copper and aluminum interlayers are topped with horizontal glass panels as long as 16 feet with corresponding colored metal connections, giving a glimpse of the shimmering, diffusive quality a facade could achieve with the same materials. According to DuPont, SentryGlas has better adhesion with the fabric mesh than Polyvinyl butyral interlayers, increasing moisture resistance and temperature stability in the long run. The Castellana 79 business and commercial center in Madrid, designed by Rafael de La-Hoz, is one of the first facade projects to be completed with the material.

As decorative patterns, interlayers, and digital printing technologies move from building interiors to facades, understanding the sunlight testing data associated with inks and technical materials is becoming more important for architects. “These technologies are relatively new in terms of exteriors,” said Bernard Lax, founder of California-based architectural decorative glass manufacturer Pulp Studio. Pulp is the only manufacturer of glass building materials using SentryGlas interlayers, marketed in North America as Chromavison. “We’re still on this path of specifications that haven’t been realized. You’ll find there are things that are not going to be performing three to five years down the road.”


As many fabricators try to get into the decorative market, similar fabrication equipment can produce radically different results depending on who is behind the wheel. “In the architectural community, the biggest problem is that designers are very influenced by sales people, but they don’t do their due diligence in asking questions about the performance,” said Lax.

Pulp recently lost a project comprising nearly 40,000 square feet of gradient sandblasted facade glass to a lower bidder who was ultimately not able to realize the architect’s original design intent. Companies operating new digital glass printing equipment without hiring art departments to tightly control image and color quality could be another concern for architects as technology advances. “It’s kind of like buying a limousine but being too cheap to hire the driver,” said Lax.

As a series of balcony glass failures in Toronto recently demonstrated, poor specification practices for even simple components can end up costing glass-heavy projects a lot of money. This summer, Ontario-based Lanterra Developments suffered a PR nightmare when glass sheets fell from the balconies of three of its recently completed Toronto condominiums. The fifth, and final, sheet to break fell from the 29th floor and hit a pedestrian below. Lanterra replaced the tempered balcony glass in all three projects with laminated glass sheets, which should remain in place even if fractured. The failures raised questions about the source of the project’s glass, and whether heat-soaked glass, which has undergone a process that would reveal any inherent flaws, was specified and delivered.

A few weeks later, Seattle’s NBBJ-designed Four Seasons Hotel and Private Residences experienced its third balcony failure and opted to replace its tempered glass balustrades with laminated lites as well. The W Austin Hotel, designed by Andersson-Wise Architects, also closed for several days in June when two falling glass sheets injured four people on the pool deck; three more lites fell in subsequent weeks. Again, the property owner replaced the tempered balcony glass with laminated panels. A report conducted by Curtainwall Design Consulting (CDC) concluded that debris from the building’s slab edges had damaged the edges of the tempered glass balconies, which were unprotected by a top railing, causing them to shatter.

Project developers and design teams have not released the sources of the failed glass, but glass fabrication experts speculated that all of the buildings used tempered balcony glass from Chinese manufacturers as a cost-cutting measure. This glass is more likely to contain nickel sulfide inclusions, impurities that can cause breakage unless heat soaking detects imperfections, which have largely been removed from domestic glass manufacturers’ products.

Buildings finished as the economy slowed may continue to see problems. “The recession especially has cultivated an ignorance-is-bliss type of attitude,” said Lax. “Most people are so browbeaten by the time they get a project, they don’t want to rock the boat. General contractors know the glass guy they hired is going to be a problem, but they can’t throw him off because he hasn’t done anything wrong yet. These things snowball.”


In spite of value engineering at every level, manufacturers remain optimistic about investing in new technologies. Glass supplier and fabricator General Glass International (GGI) is launching a line of acid-etched flooring based on increased demand for that type of application. The company also recently installed a new tempering furnace, allowing them to print and temper a 110-by-170-inch piece of glass (its previous capability was 84 by 168 inches). They will use it to manufacture digitally printed glass for Newark’s Terminal B modernization. “It eliminates an obstacle for designers,” said Richard Balik, the company’s vice president. “Bigger glass eliminates the need for metal and gives them more flexibility.”

And pieces are likely to get bigger—GGI’s furnace can temper glass up to 110 by 236 inches, but the logistics of cutting, polishing, drilling, and storing a piece of glass that size are still being worked out in the company’s plant.

“Architects are pushing us a lot,” said Don McCann director of international sales for glass fabricator Viracon. “They want larger glass and to span larger openings. It’s requiring us as a company to get larger fabrication equipment.” As a lower-cost alternative to digital printing, the company recently launched Viraspan Design-HD, a high-definition silkscreen process that creates half-tone pixels and gradation within an image or pattern. While the designs they can achieve are beautiful, they are not just decorative: Being able to engineer a larger piece of glass into a building could mean a reduction in other materials and in interior finish-out costs, and incorporating the right frit, low-e coating, or interlayer into facade glass can reduce strain on mechanical systems. “It’s a first-cost savings,” said McCann. If architects—and their clients—are on board, they can make sure the glass works for itself.