lgn2110

Enhancing the building envelope with laminated glass

Michael D. Flynn

An interview with Michael D. Flynn, Pei Cobb Freed & Partners, New York

Michael D. Flynn, a partner in the renowned New York architectural firm of Pei Cobb Freed & Partners since 1989, joined the firm in 1962. His principal activity is oversight of the building envelope and exposed structures. Mr. Flynn has been principally responsible for all of the firm's building enclosures comprising nearly 100 executed projects around the world. Pei Cobb Freed & Partners (previously I.M. Pei & Partners) has won innumerable architectural awards since the firm's foundation a half-century ago.

LGN: How have 'building envelopes' changed in the last 30 years and what has been the role of glass, and laminated glass in particular, in that evolution?

Queen's Family Court and City Agency Facility (Jamaica, New York) (construction: 2000 -): Like the federal courthouse in Boston, this family courthouse will use a glass atrium and extensive, large windows in the intimate-sized courtrooms. The goal is to reverse the introverted layout of the traditional courthouse and help connect the waiting public to the social and physical fabric of the world outside, while maintaining maximum security and safety standards.

MF: The introduction of reflective glass in the 1960s and then more stringent energy codes in the 1970s both represented milestones in the evolution of architectural glass. Before 1975 you would rarely see insulated glass (IG) units used in commercial buildings; now the opposite is true, you can hardly conceive of a commercial building without IG units. The next milestone was the introduction of Low E coatings in the 1980s and then Advanced Low E coatings in the 1990s to improve the building's shading coefficient. IG glass has become standard in commercial buildings. It delivers a high performance glazing solution in terms of energy conservation while also allowing optimal daylight transmission.

Laminated glass Low E insulated units are commonly used as part of this high performance glazing solution in colder climates. In warmer climates like the Mediterranean and Southeast Asia where IG units are less needed, laminated glass is used in a single-pane glazing solution in combination with high performance coatings to reduce cooling loads and respond to energy conservation regulations.

Jacob K. Javits Convention Center and Plaza, New York (completed: 1986/8): This huge (21.9 acre total) building was designed to house the world's largest exhibition hall and was one of the first projects worldwide to transform the traditional notion of a convention center from a large, windowless box cut off from everything around it into a welcoming public building, integrally relating to the surrounding city. Flynn: "In the Javits Convention Center's 15-story high Crystal Palace and Galleria, an immense quantity of laminated glass is used for a glazed roof and sloped walls made of vertical IG units. This enabled us to achieve a very strong geometric form."

Another milestone is DuPont™ SentryGlas® Plus ionoplast interlayer, developed originally to produce hurricane-resistant glazing solutions in Florida. This is a material that has held considerable interest for architects everywhere since September 11th 2001. Designed to protect people inside a building from flying debris in hurricanes and typhoons, this interlayer can resist a varied range of flying missiles. It protects people from consequential damage following an explosion. In general, the amount of blast a pane of glass can resist comes from two factors: the thickness of the glass and the properties of the interlayer. The advantage of SentryGlas® Plus is that we can improve the blast-resistance of the glass through the properties of the interlayer, that is, without needing to make the glass too thick.

Today, the safety and security advantages of laminated glass have never been so important. With new interlayers such as SentryGlas® Plus ionoplast from DuPont, you can design in clear, distortion-free glass that responds to security threats that architects did not need to consider five or ten years ago.

In addition, laminated glass generally provides the best safety option. If it were not for laminated glass, most modern glazing systems would not be possible. If laminated glass had not been invented, many of today's most outstanding architectural projects would simply disappear off the map! So for all of these reasons, we expect to use laminated glass in a high percentage of the jobs we do today.

Science and Engineering Quad, Stanford University, Palo Alto, California (completed: 1999): Contributing to the Quad's striking identity as a work of modern architecture, the Electrical Engineering Building has a laminated glass skylit atrium which invites entry and animates the building as it brings daylight deep into interior spaces.

Laminated glass has rightly assumed its place in today's architectural vocabulary; it is here to stay. I am excited by the increased properties it brings to the building envelope of every project that we undertake.

LGN: In addition to the functional reasons for using more laminated glass, are there aesthetic reasons for using the material?

MF: I've never had a client ask for 'fewer windows'! Our clients are increasingly aware of the importance of natural daylight when they commission projects. This comes partly from regulations - for example in Europe desks must be within a few metres of a window - and partly from research indicating that increased daylight may help people to be more productive at work, or that to be aware of sunshine and the outer world may aid in physical and psychological recovery at hospital. Getting more daylight into buildings has been facilitated by new technologies including new coatings that give high performance, low reflectivity and high light transmission. The use of laminated glass means that you can build in all these properties and avoid color distortion too.

LGN: What do you believe the future holds for laminated glass?

The Bank of China (BOC) Tower, Hong Kong (completed 1989): the challenge was to construct a tall building on a very limited site in a typhoon zone.

MF: Among the latest applications, I like the double glass walls using laminated glass that we are seeing, particularly in Europe. You typically have a perimeter zone that comprises two layers of glass, from 150 mm to 1.5 m apart. This gives you outstanding flexibility when it comes to solar control, natural ventilation and lots of daylight, particularly in tall buildings. This brings the performance of laminated glass to new heights, particularly regarding acoustics.

In summary, I think about laminated glass more and more. Laminated glass has become a hot topic in the news - particularly because of its security properties. Architects are all talking about it and wanting to know more about it than ever before.

The Kirklin Clinic, University of Alabama Health Services Foundation, Birmingham, Alabama (completed: 1992): What could have been a cold and sterile setting is humanized by the introduction of a central, skylit atrium of laminated glass to aid orientation in this very large building, as part of an overall aim to provide a physically and psychologically healthy environment.

Flynn: "In both the Kirklin Clinic and Stanford University's Science and Engineering Quad, laminated glass skylights are used to bring daylight into deep spaces in a visually exciting way, while also accomplishing UV control because of the properties of the PVB."

The Morton H. Meyerson Symphony Center, Dallas, Texas (completed: 1989) — Flynn: "In both the Morton H. Meyerson Symphony Center and the Bank of China in Hong Kong, laminated glass was the only safety option for the extensive sloped glazing. In the Symphony Center, the material is used to create very open spaces as an emphatic contrast to the closed-in traditional 'shoebox' architecture of the auditorium. In the Bank of China tower, all of the sloped surfaces are at 45 degrees. Only laminated safety glass could meet all our design objectives; it admits maximum daylight, creates a strong form and achieves the glare control we felt necessary."

Mount Sinai Medical Center

The Mount Sinai Medical Center Expansion and Modernization (Guggenheim Pavilion) (completed: 1992): The architectural assignment was to improve access, security, ambience and circulation at Mount Sinai, one of the United States' top teaching hospitals. A new main entrance leads to a plaza that is flooded with natural daylight thanks to a dramatic, laminated glass skylight that connects nearly 70 per cent of the entire hospital complex at ground floor. Flynn: "For the Mount Sinai Medical Center (Guggenheim Pavilion), a deep laminated glass light well creates a central courtyard that floods the interior of the building with daylight. This overcomes the physical constraints of the site to bring lots of daylight into each patient room."

Fountain Place (originally Allied Bank Tower), Dallas, Texas (completed 1986): This 60-story office tower takes the form of a laminated glass prism, informed by a rigorous and precise geometrical procedure employing the diagonal of a double square in plan and section. Flynn: "Here we created a strong sculptural shape using an extensive sloped wall, which would not have been possible without laminated glass for safety glazing."

John Joseph Moakley United States Courthouse in Boston (completion: 1998 - see also LGN no. 13, 1999): The Courthouse's now-famous, 'conoid'-shaped laminated glass façade asserts the principle that the courts are open to all, while giving great views of the Harborpark and protecting people inside. Flynn: "We used one-inch thick, multiple plies of glass and PVB to achieve large expanses of bullet-proof glass and achieve maximum security at ground level. The conical wall of sloped laminated glass opens the interior to the public in a very democratic way."

Grand Louvre - Phase I, Paris, France (completed 1989) and Phase II (completed 1993). I.M.Pei's glass pyramid was one of the first major projects to bring architectural laminated glass to the attention of the global architectural community and to the public alike. Flynn: "The Louvre Pyramid was designed to bring daylight into a deep underground space. People noticed it as a remarkable sculptural piece but it's actually amazingly functional. You can tell how well the laminated glass pyramid is working by how much daylight is being directed down into the main reception hall. The inverted pyramid and the skylit sculpture courts of Phase II of the project are continuations of this theme. Inside, you feel respite and calm due to the silence and the quality of the natural light."

The John Fitzgerald Kennedy Library, Boston, Mass. (completed: 1979; extension completed 1991): After viewing a film about Kennedy's life in an underground gallery, visitors emerge from the darkened setting into the sun-filled, silent void of a space-framed, laminated glass pavilion. Except for an enormous American flag, the space is empty and invites contemplation against the background of Boston's Dorchester Bay and the Atlantic Ocean beyond. Flynn: "In the JFK Library we used laminated glass in the skylight and for special soundproof windows in the research areas."