(JBED) - Summer 2006 - The Whole Building Design Guide

More documents

Recommendations

Info

systems have a significant and fascinating cultural component. Façade openings in Europe have always had numerous “switches” in them, operated by the building Figure 2 - Hannover Messe A.G., Hannover, Germany, 1999. Thomas Herzog + Partner. Figure 3 - Helicon Building, London, UK, 2000. Sheppard Robson International. Figure 4 - Plantation Place, London, UK, 2005. Arup Associates. Architects. 20 Journal of Building Enclosure Design user. Traditional windows in Italy have an outer layer of louvered shutters, glass in a casement sash, light filtering curtains and a solid inner shutter of wood. Each can be deployed to block, filter or admit elements of the exterior world. In the United States we have used building technology to eliminate switches, as insulating glass eliminated the storm window. European double façades are expanding the benefits of switches, using technology to automate rather than eliminate them. In commercial buildings a large percentage of the glass remains operable with building ventilation coming directly through the façade. The first new applications of double skins were “re-wraps” of existing buildings, such that the operable outer leaf works in tandem with the original façade to enhance building performance through both the heating and cooling seasons (Figure 1). This strategy remains one of the most cost effective applications of the double skin. From these beginnings, the new façades rapidly progressed to become spectacularly intricate machines that contribute to a wide variety of building climate functions. Thomas Herzog’s Hannover Messe A.G. is a mature example of a “corridor façade,” with the inner glass leaf set back on the floor slab around the entire perimeter of the occupied space (Figure 2). The façade expression is dominated by its role in the ventilation scheme. With the service cores removed from the central block, the buffer space accounts for 22 per cent of the remaining slab area. This is an investment in passive strategies that few in the U.S. would be willing to consider. The quality and performance expected of German buildings is part of their culture and manifest in their regulatory system. Office buildings must provide workers with daylight and fresh air through an operable window within a specified distance from each station. German texts make it clear how these requirements have fueled the development of double skins (Oesterle, 2001). However, as energy conservation goals have risen, all the components and systems have improved and the potential for savings through the addition of a second skin has become less. As the examples will show, German architects have become more focused and strategic in their use of the double façade. THEMES OF PRACTICE In London, the exuberant use of technical systems has long been part of the commercial building culture. The Lloyd’s Bank (1986, Richard Rogers) and the New Parliamentary House (2000, Michael Hopkins) both have ventilated façade cavities in addition to their more famous expressive elements. The engineers and architects at Arup and Arup Associates have had a formative influence on “high tech” work. Using extruded sections and machined fittings, in the 1980’s Arup crafted robust and expressive external shading devices that cantilever off the building façade (One Finsbury Avenue, London, UK, 1984, Arup Associates). The work of Peter Rice added large expanses of suspended glazing to the British vocabulary. Once these two themes of practice were firmly established, the double skin became a logical progression. Adding a glass leaf to the outside face of the cantilevered shading structure allows the fixed louvers to be exchanged for much more effective operable systems and admit diffuse light on overcast days and track the sun when shading is an issue. The Helicon Building in London offers a dramatic example (Figure 3). Engineered by Arup, the building has a monumental double façade suspended over the south entry. Inside the stack ventilated cavity are gigantic louvers. Not far away, Plantation Place offers a different integration of the two venerable themes (Figure 4). The façades are made with a repetitive unit curtain wall system. Close to street level the modules are matched to suspended external shades made of stone, in response to the context. As the floors mount, the plan steps back to form twin towers dominated by interactions through the skin. The same façade unit develops a cantilevered cavity with maintenance access and an outer leaf of glass shingles that are open jointed to discharge the heat absorbed in the small scale, operable louvers. This building does not function in all the modes of the German examples, but it also has far fewer moving parts. It is part of the trend in which architects are trying to capture the major benefits of a double skin through more efficient means. BRAND IDENTIFICATION The Arup offices in London occupy a rehabilitated building with a double skin
façade at the street corner. It is therefore one of the most potent of motivations, marketing. Arup is projecting a contemporary image of the environmentally responsive building that has enormous appeal to corporate clients. Returning to the Helicon Building, with the monumental façade, one must note that other faces are tempered by a much more reserved version of the same thermal chimney approach. The core of the building receives its light from an atrium space. The huge system above the entry hangs in front of a shallow band of offices no greater in volume than the façade cavity itself. That this flamboyant gesture survived the hard sums of a commercial project is a testament to the power of brand identification and the role of the double skin in realizing that ambition. Another vivid exemplar is a building on a prominent site in central Stuttgart (Figure 5). It has the shape of a teardrop with the pointed end reaching out toward a main thoroughfare. The plan becomes so narrow that fully one third of the outer glass leaf has nothing behind it except the cavity space. THE UNIVERSAL, ALL GLASS FAÇADE The RWE headquarters in Essen is a beautiful cylindrical tower that is considered by many in the field to be the most elegant of double skin façades (Figure 6). It faithfully realizes the historic imagery of Mies Van der Rohe’s project for an all glass skyscraper and strives to develop the “neutralizing wall” advocated by Le Corbusier many years ago. This building, and others like it, are driven by a renewal of modernist theory, now with the technical means available to try to realize those visions. The Essen tower is defined as a corridor façade, segmented at each floor plate. It is also a unitized, double curtain wall with cross-over ventilation between adjacent cells so that the intake and exhaust air streams are separated. The façade elements demonstrate a commitment to repetitive production, although they are so precise and intricate they should in no way be referred to as economical. The cylindrical shape optimizes the surface to volume ratio, but it also makes the building indifferent as to solar orientation. This is the double skin proposed as a universal solution that can be deployed with equal enthusiasm to the north, south, east or west. There is, in Frankfurt, a newer tower that makes an interesting comparison (Figure 7). The work of Schnieder + Schumacher responds to the modernist legacy with equal intensity. Here the glass cylinder is pure, without accessory elements at the top or the base. The original concept called for buffer spaces that would ascend in a spiral similar to Norman Foster’s “Gherkin” in London (Swiss Re, 30 St. Mary Axe, 2004). In Frankfurt, the building has no major tenant to foot the bill and double skin techniques are reaching down into a speculative market that demands greater efficiency of means. As constructed, a square floor plan with a very simple glass façade is developed inside the protection of the outer cylinder. The difference between the two shapes produces four segmental buffer spaces, two in front of partitioned offices and two as “winter gardens” outside of open desk space. The cavities are segregated every four stories by a full circular floor plate. The outer leaf, executed skillfully by Gartner, has operable units in the upright triangles of the ornamental façade pattern. These ventilate the buffer spaces on demand. The scheme is beautiful in its conception, but again indifferent to solar orientation; a triumph of theory over the realities of nature. The cylinder is once more proposed to minimize surface area, but since the building is so often in cooling mode, a concern for skin losses is a suspicious motivation. GREEN ARCHITECTURE The double skin takes a different role on the palette of architects who try to connect to nature rather than neutralize it. Exemplary of this approach is the work of Behnisch, Behnisch and Partner, with climate engineering by the well known firm, Transsolar, also of Stuttgart. This team has worked closely on a number of projects including the NORD/LB headquarters in Hannover, Germany (Figure 8). For Behnisch and Transsolar, the double skin in not a preconceived solution, but just one of many tools taken up in order of their effectiveness. In fact, the double skin may be quite far down that ranked list. At NORD/LB the first concern is connecting the building occupants to the richness and variety of the environment outside the glass. This includes views, ample Figure 5 - Landesbank Baden Wurtemberg, Haus 5+6, Stuttgart, Germany, 2004. Wohr Mieslinger Architekten. Figure 6 - RWE A.G., Essen, Germany, 1997. Ingenhoven Overdiek Kahlen and Partner. Figure 7 - Westhaven Tower, Frankfurt, Germany, 2003. Schneider + Schumacher. Figure 8 - Norddeutsche Landesbanke (NORD/LB), Hannover, Germany, 2002. Behnisch Behnisch and Partner.
Page 1: JBED Summer 2006 Journal of Buildin
Page 6: Message from NIBS David A. Harris,
Page 10 and 11: Feature Dynamic, Integrated Façade
Page 12 and 13: 1. COMMERCIALLY AVAILABLE SOLUTIONS
Page 14 and 15: procure them for the final building
Page 16 and 17: obstruction and/or daylight reflect
Page 19: Feature All That Glass Is there an
Page 23 and 24: cess to the perimeter, concrete str
Page 26 and 27: Feature Architectural Glazing for S
Page 28 and 29: could consist of lites that have di
Page 30: esidents. Another concern from the
Page 33 and 34: from the California Central Valley
Page 37 and 38: Feature Window Comfort & Energy Cod
Page 39 and 40: By Valerie L. Block and Tammy Amos,
Page 41 and 42: Feature How Does Fenestration Fit I
Page 43: Council (ICC), one might expect tha
Page 46 and 47: Industry Update By James C. Benney,
Page 48 and 49: BEC Corner HOUSTON-BEC By Andy MacP
Page 50: Buyer’s Guide AIR BARRIERS Dupont

(JBED) - Summer 2006 - The Whole Building Design Guide

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?