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Karen Cook AIA of Kohn Pedersen Fox, London:
“Challenging traditional expectations using laminated glass”

Karen Cook

Kohn Pedersen Fox was founded in 1976 by A.Eugene Kohn, William Pedersen and Sheldon Fox. The practice has since grown from three to over 400 people, has added offices in London and Tokyo and has worked in over 30 countries. KPF’s strong body of work has gained it recognition as one of the most respected architectural design firms in the world. Karen Cook FAIA joined Kohn Pedersen Fox New York in 1984 and was one of the original group to set up the London practice in 1990. Karen Cook holds a Master of Architecture degree from Harvard University, and Bachelors degrees in Architecture and Art from Rice University, Texas.

“A transparent contrast to solid volumes”
Ms Cook told LGN: “A lot of architects these days use laminated glass as a transparent contrast to solid volumes in the context of retaining structural strength. In the River City project in Prague, laminated glass is used in this way, both to facilitate views out and give an image of transparency from the outside, important for many corporations today.

“Getting daylight into deeper floor-plates is important to most of our commercial projects today – for example at Thames Court in London where clear laminated glass is used. There are codes in northern Europe that specify the amount of natural daylight that should come into offices.

“Sometimes we use laminated glass to challenge traditional expectations – for example, in the Rodin Museum in Seoul we played on the translucent, dual (translucent but also solid and object-like) unexpected possibilities inherent in laminated glass. In the Gannett/ USA Today building, we used high performance laminated glass to reduce radiant heat gain while giving the building the appearance of a solid object.

“Structural and sculptural role”
“For the past 10 years, glass has been primarily perceived and used as a transparent surface or skin. Now, architects are more interested in investigating the structural properties of laminated glass, in seeing how it can play a solid or sculptural role in projects.

“Together with Jean Lelay of structural engineering firm RFR in Paris we are exploring the structural possibilities of laminated glass in the Prague River City project, Czech Republic. This is the biggest architectural development to take place in the new development of Prague. It features a complex, 70-metre long, sloping glass atrium of laminated glass and a folding laminated glass wall. The glass is being supplied by a local Prague firm called Sipral. The Endesa project in Madrid was quite an experience with exploring the structural properties of laminated glass using the new ionoplast interlayer from DuPont. However, Prague takes the quest further.

“The city of Prague has a proud tradition of glass artwork, an expertise in cut glass surfaces that can remind you of an early Braque painting. We wanted to refer to that tradition in an abstract way at the River City project. The sloping glass roof is quite sleek; it gives the effect of a series of triangular shapes. Every 5.5 metres, it zigzags out by a metre. These projections are constructed of laminated glass. The folds assist the wall to perform lateral wind load resistance.

“We certainly view laminated glass as an efficient structural member. In a separate atrium within our Prague project, we use laminated glass for a 50-metre long atrium wall that is three stories high. Here, you have a flat wall of laminated glass that is constructed in order to give the impression that the wall does not exist. What the eye sees is a spectacular view of a river and trees. With the help of RFR, the laminated glass wall is effectively transformed into a three-storey opening in the building envelope.

“Continuing on the theme of challenging traditional expectations we reversed the normal expectation that glass is fragile and cannot support the load of the building in River City, Prague, where the building seems to float above the laminated glass walls.

“In the Prague project we are using a huge meterage of glass for the atrium but we know from Finite Element Analysis (FEA) calculations that if the roof gets broken by something being dropped on it, the glass will not fall out. So the safety factor is always important. But nowadays we also expect laminated glass to play a major role in the structural integrity of the roof. We make our FEA calculations in such a way that the glass and the metal elements work together towards the strength of the building envelope.

Special aesthetic effects
“We use laminated glass a lot in our projects because it fulfils the code requirements and because you can achieve aesthetic effects such as patterns, colours, shades or frosting in the PVB in a pretty efficient way.

“Laminated glass can also form a very effective screen. For example, in the Rodin Museum we used the large folding glass wall to separate the activities going on in the lobby from the busy road outside. By using laminated glass in a floor to ceiling translucent screen, a sense of calm is instilled and people can focus on what’s going inside rather than being distracted by the outside noise and bustle.

Glass floors
“In the Thames Court (London) project, we made the lift, lobby and floors out of laminated glass in order to allow in the greatest amount of natural daylight. The light core of the building is placed between an internal atrium used for offices and an entrance hall. The sense of daylight coming through the floor plan is very strong. You essentially have a glass roof suspended over a transparent space. If we had not used so much laminated glass in this project it would not have been possible to introduce so much light into the middle of the building.

New textures and shapes
“Lastly, we like to use laminated glass to introduce a range of textures into the glazing. For example, in AIG’s European headquarters in London we used vertical glass fins on the exterior of the building not so much for external sunshading (this is not usually a problem in London!) but because the use of fins transforms the curtainwall from being a flat surface to an interesting surface that plays with depth and shadows.

“As a general note, all of our clients want to be reassured that we are meeting government regulations for the glazing and that is a given. But as architects, we are usually looking for the clearest glass that has not been heat-treated and with laminated glass you can achieve that. We enjoy working with suppliers like Cricursa and Interpane who can really help us in achieving aesthetically pleasing laminated glass applications. For example, in Prague we use rounded laminated glass for the panoramic lifts in the atrium. We use laminated glass in different ways for different projects according to the client’s functional and aesthetic goals. We are delighted that laminated glass is such a versatile building material.

The future: more invisible technology
“For the Endesa project, it was really a pity that the client did not opt to use photovoltaic cells in the roof, as we had originally proposed. That would have been great for Endesa’s drive to become a global environmental energy leader. It’s important for the public to see and understand that environmentally-responsible architecture can also be great to look at, and that we can integrate the technology into the beauty of laminated glass and enhance the overall architecture of the building too.”

1. Thames Court, London (completed: 1998) ©KPF Thames Court, London (completed:1998) a frontal view at night, showing the use of clear laminated glass creating a grand frontispiece, which unifies the smaller office module partially visible behind. This atrium buffers the offices from the noise of the road, and creates a slice of space into which one enters the building. "Thames Court is ideally suited to our needs a major international bank, allowing us to accommodate the inevitable moves and changes arising from the dynamic market place in which we operate. The superb river location has been optimised with the building’s design elements combining seamlessly to create an excellent working environment of a standard appropriate for our Triple-A rating." Rabobank International London Branch The Thames Court office building combines clarity of intent, the most rigorous efficiency criteria, and a humane and interesting use of space, light and materials. The design includes deep floors suitable for dealers and more conventional 18 metre deep bars of space with daylight on both sides to provide different types of work environments. They are linked by a sequence of internal public spaces each with a distinct spatial and material character. ©KPF Thames Court, london: a typical lift lobby, with glass floors (laminated for safety and structural reasons) supported by cast aluminium brackets. The deep floorplate benefits from the glass floors which let light pass the central circulation space, adjoining a central atrium used as a trading floor (which you can just see in the background). Glass clad lift shafts and floors provide transparency. Operable windows provide natural ventilation and individual control. An innovative roof light shading device is responsive to seasonal variations and diffuses natural light into the offices. The project is used by the City of London’s City Planners as a benchmark for excellence in design.

2. Gannett/ USA Today HQ (completed: 2001) This new headquarters is located on a 30-acre site outside of Washington, DC. Two entities, the structures for USA Today and Gannett sit on a corporate base and spiral up to enclose an exterior "town square". ©KPF The Garret / USA Today building, located outside Washington DC (completed 2001): an interior lobby view showing clear glass wall.Viracom and Depp Glass both supplied laminated glass for this project. There are three major programmatic elements: the common (shared) facilities, the newsroom and production areas and the typical office areas. Common spaces are distributed along the entry level. Newsroom and production are in high-ceiling areas on podium levels two and three. Typical office spaces are above in linear towers; designed for maximum flexibility, the narrow tower footprint allows maximum natural light to all offices. The design orients the complex and its community space towards the pond at the center of the site. The southern orientation maximizes sunlight into the exterior courtyard and adjacent terraces. When Gannett moved from an urban high-rise work environment to a suburban location providing considerable potential for site amenities, the ability to design a more flexible space to facilitate integration of a new technology for a productive workplace emerged. There was the opportunity to create a building that fosters and promotes a sense of community for the entire staff. The project represents a complete re-thinking of the suburban office building to utilize the space-making potential of the linear building form and to create a composition that unites the programme elements of the building with the natural site features. The varied properties of laminated glass make it possible to define the building not only as an open community but also as a gentle reflection of the surrounding natural landscape. The project consists of two linear buildings (occupied respectively by the corporate structure and its newspaper division) on a common base – the two linear structures spiralling up to enclose an exterior ‘town square’. The glassy single-loaded circulation system expressed on the courtyard side of the buildings, and the articulated elevator towers with zones of clear and translucent glass skin, activate this inner space. The facility includes three basic programme elements. Common spaces are distributed at the entry level of the complex; flexible, deep newsroom and production spaces occupy high-ceiling area on podium levels two and three, and typical office spaces are located above in linear towers, designed with flexibility for departmental change and oriented on the site to maximize views. The narrow footprints and high ceilings allow maximum natural light for all occupants. The varied properties of laminated glass were studied carefully to accentuate the sculptural quality of the architectural forms and to explore and make explicit the reciprocal relationship of interior and exterior space. Lightly reflective glass, used throughout most of the building exterior, has been augmented by projecting vertical glass fins (75 cm module) that give the surface a crystalline quality and accentuate the angular relationship of planes seen frontally or obliquely. Clear glass defines the zones of collective spaces where people gather and circulate, and allows the active connection between inside and outside. Between the clear and the reflective are variations on translucency. At the elevator towers, zones of clear glass with a fritted horizontal line pattern, or with the frit pattern sandwiched with translucent opaque glass, provide layers of translucency and veiled, scrim-like transparency. Acid etched laminated glass is translucent at walls, screen walls and bridge floor, and vaguely reflective where backed with an opaque mirrored surface at the elevator cabs. At the custom elevator call lanterns, layers of clear glass with bevelled corners are laminated and edge-lit. Glass guardrails provide security at stairs, bridge and terraces. Laminated glass skylights at terraces, atrium and harp stair celebrate light in the major public spaces. One of KPF's most well-known projects using laminated glass to stunning aesthetic effect is the Rodin Museum, Seoul, Korea The whole structure may be thought of as a study of glass and its materiality, reflectivity, transparency and the manner in which it can create an exciting and productive environment and augment the quality of architectural form. The laminator for the skylight, atrium and elevator tower was Viracon, which used a ¼ inch clear outer lite with low-E coating with silver colour ceramic frit line pattern on the no. 2 surface, ½ inch air space, 9/16 inch clear laminated inner lite insulating glass unit. Viracon also supplied the laminated glass fins, glass of two lites of 5/16 inch thick annealed glass bonded with 0.040 inch, thick clear liquid interlayer for a nominal 5/8 inch overall thickness. The laminator for the floor of the lobby bridge and elevator lobby walls, the atrium feature walls, the security desk and the elevator cabs was Depp Glass Inc. Clear glass was used for the lobby bridge floor and the elevator lobby wall while translucent laminated glass was used for the atrium feature wall.

3. River City, Prague (under construction) ©KPF River City, Prague. The "River City Prague" site is located on 6 hectares at the tip of a 66 hectare disused railway yard, parallel to the Vltava River along Rohansky Nebrezi. It forms an extension of the district Karlin, Prague's first suburb built in the 18th century immediately outside the original city walls. It is only one underground transport stop from the central downtown station, and only a few minutes walk from the city centre. Pedestrian bridges will strengthen the integration of the new development with the existing city fabric by connecting Karlin to an adjacent sporting facility located on Stanice Island in the Vltava and on to the Market on the north side of the river. KPF's scheme develops the first four buildings and infrastructure of the initial seven in the Masterplan. A city block structure sponsors the future growth of the larger site. Although the site is integrated with Karlin, it begins a new era in the development of Prague and eventually will be a new district with its own character and identity. ©KPF River City, Prague (under construction): features a 70-metre long, sloping atriumof laminated glass and a folding laminated glass wall( shown above, under construction). The structural possibilities of laminated glass were explored in this project by KPF together with RFR of Paris. The initial concept design takes advantage of the naturally landscaped setting. Interlocking open spaces bring the landscape into the building, redefining nature spatially on the building's exterior as gardens and environmental buffers. Interlocking forms containing the offices complete the total volume. All building entrances are from a central boulevard, which will extend through the future development as a central spine. Arcades aligning the street create a protected pedestrian route. The area will be inhabited 24 hours a day due to the mix of functions.