DYNAMIC AND ADAPTIVE SURFACES ON TALL ...

Proceeding of the International Scientifical Conference. Volume III.

DYNAMIC AND ADAPTIVE SURFACES ON TALL BUILDINGS Alessandro Premier Iuav, University of Venice Abstract. Despite the severe crisis that is affecting the construction industry in the Western World, in the contemporary global landscape the construction of tall buildings seems to be still very relevant. Huge buildings that probably will remain unsold (at least partially) characterize the new skyline of Milan, Abu Dhabi, Dubai and Shanghai. In the configuration of these buildings the glass skin has always played a very important role: curtain-wall façades and cells façades are born for them. Today, the evolution of these façade systems seems to be directed in two different ways: on one hand we have the integration of green in the building envelope, on the other hand we have adaptive façades, able to change their configuration with different environmental conditions. The paper focuses on this second line of development by analyzing the possible solutions of architectural integration emerged from a survey carried out on a number of case histories.. The objective is to understand how the appearance of the city could change through the use of new dynamic and adaptive façades in tall buildings. Keywords: High-Tech architecture, dynamic façades, adaptive façades, tall buildings, environmental quality, architectural design

Introduction Man has always tried to exceed his physical dimension through the construction of impressive artifacts. Many of them were buildings. This kind of desire led to the construction of tall buildings. The first tall buildings were dedicated to the religions. In the ancient world, buildings like the pyramids of Giza (XXVI century BC) and the ziggurats of Mesopotamia (XXI century BC) seem to represent man’s desire to get closer to heaven. They were built in the desert and made of stone, symbolizing the eternity of pharaohs’ power and they had to be immutable for centuries. In Roman times the towers were purely defensive constructions. In the Middle Ages, since the Tenth Century, the defensive towers began to be used as dwellings. This lead to the phenomenon of the tower-houses. The most important families had to acquire high and well-fortified houses to protect themselves from enemy attacks. The height of the tower was the symbol of the power of the family who lived in. The skyline of the city was characterized by a number of tall buildings made of bricks and stones. In Italy, in the late Twelfth Century, with the growing importance of municipal institutions, the city governments decided that the buildings should not be higher than the tower of the town hall. So, many towers were cut and the city skyline acquired a more uniform shape. Until the Nineteenth Century the tallest buildings were the bell towers. In fact, tall buildings were particularly at risk with the new firearms.

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At the end of the Nineteenth Century the new building systems changed once again the appearance of the city. With steel frames and reinforced concrete, architects had the opportunity to build the tallest buildings ever made. The Chicago School was very important for this phenomenon. It was a group of architects who, after the burning of the city in 1871, devoted themselves to the design of the new town. The new Chicago was the city of skyscrapers. The first building of this type was the Home Insurance Building (1885) designed by William LeBaron Jenney. In a short time, many towns of the US changed their shape with new skyscrapers. In 1930 in New York we could find the Chrysler Building (319 meters) and, only a few months later, the Empire State Building (381 meters), which remained the tallest building in the World until 1973. The metal frame allowed the construction of increasingly lighter walls characterized by increasingly larger windows. The glass gradually took more and more importance in the configuration of the façades of these buildings. The facades were no longer made of stone or bricks. Designers were fascinated by the possibility to make huge glass buildings. The famous glass skyscraper designed by Mies van der Rohe in 1921 for Berlin, materialized the dream of an entirely glass architecture developed by the intellectual Paul Scheerbart (Glasarchitektur, 1914) and by the expressionist architect Bruno Taut (Glaspavillon, 1914). The Seagram Tower in New York (1954), designed by Mies van der Rohe, with its glass facade punctuated by vertical and horizontal steel elements, has been a model for many other architects. In fact, in Manhattan you may see many buildings that reflect Mies’ project. In the new tall buildings, made of steel and glass, the external skin plays a central role. Lightweight façade panels and curtain-walls are the basic elements for the construction of tall buildings’ architectural skin. Even the development of cells façade systems or spider glass façade systems is closely related to this type of construction. Today, the design of the tower buildings is proceeding hand in hand with the development of façade technologies. And the evolution of façade systems is reflected on the evolution of the appearance of the contemporary city. Contemporary trends The use of steel and glass in the construction of tall buildings produces very high operating and maintenance costs, with a very high level of energy consumption. Costs and pollution increase in proportion to the size of the building. In order to reduce energy consumption and to improve the environmental quality of the interior spaces, the research has increasingly focused on the improvement of the external building envelope. The building envelope is now designed as a “dynamic interface” (See Altomonte, 2004), i.e. able to relate actively with the external environment.

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Trying to give an answer to these instances, the research seems to be directed towards two different solutions that seem opposite to each other. On one hand there is the integration of the green into the architectural surfaces as an element of climate mitigation. An example is represented by the Vertical Forest designed by Stefano Boeri for the city of Milan (2012). On the other hand there is the development of dynamic façade technologies for the control of the solar radiation. The first solution seems to follow the tradition of climbing plants on the walls of the buildings. However, these systems need very complex technologies of water support and drainage. The projects that follow this trend are numerous: Harvest Project by Green Romses Architects in Vancouver (2009), Dragos Towers in Istanbul by Superpool (2009), Eco-Friendly Tower in Singapore by TRHamzah & Yeang (2010), Végétale Tour de Nantes by Edouard François (2011) and many others. Most of these projects suggest an idea of the city where the surfaces of the buildings are filled with green as opposed to the traditional idea of a clear distinction between natural and man-made environment. The second solution provides the development of façade technologies able to establish a two-way relationship with the surrounding environment. These systems are called “dynamic surfaces” or “adaptive surfaces”, i.e. able to adapt to different environmental conditions, to ensure an optimization of the indoor comfort and energy consumption of the building. These technologies include the use of sun shading systems often integrated with smart materials and technologies. These cutting-edge technologies can draw the outer surface of the buildings. In the words of Axel Ritter, author of the book Smart Materials in Architecture, Interior Architecture and Design, “smart materials is a relatively new term for materials and products that have changeable properties and are able to reversibly change their shape or colour in response to physical and/or chemical influences, e.g. light, temperature or the application of an electric field. […] With smart materials these changes are repeatable and reversible” (Ritter, 2007, p. 8). The integration of these new technologies and materials with the sun shading systems has produced what we call “dynamic and adaptive façades”. Dynamic and adaptive façades Adaptive façades have been designed to provide a modular control of the sunlight and of the internal micro-climatic conditions, especially during the summer. The most important cultural reference for adaptive surfaces is the south façade of the Arab World Institute in Paris, designed by Jean Nouvel in 1988. The large glazed area of the façade is protected, from the inside, by a complex system of moving diaphragms (similar to those of the cameras) to control the sunlight. For a long time this building has been an almost isolated case, because a system consisting of 240 façade modules and containing more than 20 shading 137


elements was very difficult to operate. Moreover, the color and light rendering of the interior spaces did not seem to fully satisfy the users. Over the past decade, the architectural research seems to have recovered the idea of Jean Nouvel, trying to integrate together two very important aspects: the continuous evolution of the design of the sun shading systems and the need to the enhance energy saving of the buildings. The research was then concentrated on the shapes and colors of the moving parts of these systems. The technological development has focused on the materials and the operation systems of these tools. This has led to new shading devices using smart materials and smart technologies to obtain a global lower energy consumption. The use of these technologies seems to have found particular success in the construction of tall buildings where there is a large use of glass and transparent/translucent surfaces. The success of the glass surfaces is not only due to expressive issues, but it is often linked to the need to capture as much light as possible in the towns where the presence of tower buildings is very dense, especially on the lower floors where the sky can be seen with difficulty. Glass also is a response to the desire to create a 360 degree viewpoint of the city. In 2010 Decker Yeadon, a studio of New York City, has developed a doubleskin glass façade shading system for large buildings. Whereas the current model of curtain wall double skins has a simple air cavity embedded with adjustable louvers, this system hosts an advanced shading system that includes mechanisms modelled after muscles enabling the system to automatically regulate heat loss and heat gain. This system is called “Homeostatic Façade”. Homeostasis is the natural phenomena in plant or animal organisms wherein they constantly regulate their internal conditions through any number of actions. Human sweat is an example of our homeostatic response to a high level of heat gain. Technologies like these bring architects one step closer to designing buildings that intelligently regulate themselves in the same responsive ways organisms do on a systems and processes level. The system takes advantage of the flexibility and low power consumption of dielectric elastomers. The automatic response to environmental conditions is achieved through a simple actuator. “The actuator is an artificial muscle, consisting of a dielectric elastomer wrapped over a flexible polymer core. Expansion and contraction of the elastomer causes the flexible core to bend. A roller at the top of the polymer core ensures smooth motion as the elastomer moves. The dielectric elastomer includes silver electrodes on both faces. The silver assists the system by reflecting and diffusing light, while distributing an electrical charge across the elastomer, causing it to deform” (Decker Yeadon, 2010). The low energy consumption derives from the fact that the surface material is also the motor and offers localized control along any segment of the façade. In 2013 the architectural firm AEDAS has completed the Abu Dhabi Investment Council towers. The design concept sought to deliver the clients requirement for 138


two landmark towers to accommodate the offices of the new Investment Council together with the Bank’s new Headquarters. The two towers occupy neighbouring plots on two adjacent sites situated close to Al Qurum beach in the eastern district of Abu Dhabi. All the aspect of the design of the towers started from the concept of a geometric pattern derived from Islamic traditional Mashrabiya design. The new Mashrabiya became the shading system of the glass envelope of the two towers. The Mashrabiya screen solution has responded to the United Arab Emirates’ aspiration to become a leader in the field of alternative energy. The preliminary studies suggested that the screen would result in a 25 per cent reduction in the cooling load, thereby substantially reducing the carbon footprint of the Abu Dhabi Investment Council building towers. The Mashrabiya comprises a series of components, each of which opens and closes in response to the sun’s movements ensuring solar gain is minimised at all times and contributing to glare reduction (Cfr. AEDAS, 2012). The shading element’s shape, when opened, is similar to the Mercedes Benz “star logo”. The screen is made of tissue and it is moved by a special steel structure. When closed the screen creates an opaque veil that covers part of the building glass envelope, maintaining the triangular structure of the façade pattern. Environmental integration The façade patterns achievable through the use of dynamic surfaces are very different. A part of them is inspired by the tradition of sun shading systems, mainly referring to those typical of the Arab world. They are geometric patterns based on a triangular figure or made with other polygons (pentagon, hexagon etc..). More conventional patterns come from the tradition of brise-soleil and adjustable louvers. They are constituted by horizontal or vertical stripes able to rotate around their own axis. These patterns have recently been re-designed to get twisted strip made of shape memory materials or composite materials such as the shading systems of the 2012 Yeosu Expo Pavilion designed by Soma Architecture. Other devices have their origin in organic shapes like the Homeostatic Façade System designed by Decker Yeadon. Other systems consist of simple square or rectangular panels able to open and close as doors, often made with perforated materials. Other systems are inspired by curtains, etc. The dynamic surfaces are now part of the architectural design process. Assuming the importance of architectural elements, they contribute to the design of the building envelope. For the fact that they are mobile, they can change the appearance of the building during the day. The façade of the building may be more or less permeable. If the shading elements are colored or iridescent, the façade can change its color. The chromatic interaction between the sun shading elements and the skin of the building seems to be very important. If the adaptive devices are placed in a glass double skin façade, their color will be lighter, almost obscured by the reflections of the glass, enhancing the dematerialization 139


of the building envelope. If the devices are hidden (like retractable blinds) the glass surface will stand out more. If the dynamic devices are placed in front of the glass surface, the outer skin will be strongly characterized by their presence. Of course, the presence of dynamic surfaces in tall buildings may condition the perception of the surrounding environment in addition to the perception of the building itself. High-rise buildings with dynamic surfaces included in the double-skin system may be likened to large crystal buildings because their perception is conditioned mainly by the external glass surface. Many of them are included in the urban centers. The shading devices positioned in the double skin space can be very light, also made up of very small elements. The Homeostatic Façade System by Decker Yeadon (Figure 1) creates a pattern formed by a set of sinuous elements that, once closed, enhance the glass surface of the building during the day. The glass surface reflects the colors of the surrounding buildings and the white flashes of the sunlight. The surface pattern looks very slight. When the elements of the shading are opened the façade become darker, assuming a silver-gray coloration similar to the metal skins of the surrounding buildings. The ability of the building to constantly change its appearance with the surface movement, allows this part of the city to be always different during the day.

Fig. 1. Homeostatic Façade System. Image courtesy of Decker Yeadon, NY

The appearance of the building may change radically if the sun shading elements in the double skin are colored or even multi-colored as in the GSW tower in Berlin designed by Sauerbruch & Hutton. In that case, the dynamic surfaces realized a game of colored clusters, highlighting the building in its context characterized by shades of gray. The color of the surfaces is very important 140


especially in suburban areas where the chromatic whole tends to blur in a color that is very close to the tones of gray. The dynamic surfaces positioned on the outer skin of tall buildings seem to have a greater impact on the perception of the building in the context, especially for the fact that they must be very resistant from a structural point of view. An emblematic example is the Kinetower®, designed by Kinetura, where the external surface is made up of huge dynamic elements. These kind of buildings seem to be mainly located in areas that are not too much urbanized and characterized mainly by lower buildings. In many cases they are relatively spaced from the other buildings and placed in a location that involves green and parking areas. Architects and Designers Xaveer Claerhout and Barbara Van Biervliet (Kinetura) believe that objects and architecture should have the ability to transform in a physical way, depending on the needs of the moment, by using the flexibility of specific materials. They believe that the outline and the proliferation of this new aesthetic will reinforce the necessary research, give more focus to cross-disciplinary development, speed up the research and development and lower the prices of the needed smart materials and components. The morphing outside layer of the Kinetower® (Figure 2) controls the amount of light that can penetrate trough the windows. At the same time the restrained light or energy can be captured to be re-used. The Kinetower as also an energy-regulator. The outer skin of the building is made of a shape memory material that contracts and relaxes automatically in relation to the external environmental conditions.

Fig. 2. Kinetower®. Image courtesy of Kinetura, B

The skin of the building is characterized by vertical cuts which constitute a set of bends able to compress and decompress, opening and closing as the fingers of a hand. The building has been designed for a green area, quite a distance from the city center.

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Also the aforementioned Abu Dhabi Investment Council Towers have been designed for a place with few buildings (Figure 3).

Fig. 3. Abu Dhabi Investment Council Towers. Sketch of the Author

The color of the external shading system is similar to the color of the sand that characterizes the horizontal surfaces of that part of the city. The shape of the buildings does not relate to other elements of the context. The only vertical elements of the landscape are the palm trees along the road that passes in front of the two towers. In the background we may see the city of Abu Dhabi, with its tall buildings that are not very different from the two towers of the Investment Council. Conclusions The dynamic surfaces are very important for the control of micro-climatic performances of the buildings, in particular of huge buildings characterized by large glass surfaces, as the skyscrapers. In addition to a performance advantage, the use of these surfaces may bring a very important contribution to the design of new façades and also to the design of parts of the city. The dynamic surfaces can be placed in a double skin system, with less impact from a visual point of view. The dynamic surfaces, placed outside the glass façades, completely redesign the building skin, having a huge impact on the context. The context in which the building is placed seems to be very important in relation to the sun shading systems that are used. In the urban centers some architects seem to prefer double skin façade systems with integrated dynamic elements. Outside

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the urban centers some architects seem to prefer external sun shading devices. As always, there are no absolute rules to qualify a situation and the architectural plan requires a careful analysis of the context. Summary Despite the current global economic crisis, tall buildings still seem to have some importance. Their story takes us back to the Modern Architecture made of steel and glass when adjustable brise-soleil was born. Over the time, the sun shading devices became adaptive devices, changing their shape in relation to the environmental conditions to provide the building a better micro-climatic performance. The growing importance of these technical devices has made them increasingly important also for the architectural design of the façades. Adaptive and dynamic façades were born this way. Today the researchers are working to combine the shape of these elements with the use of smart materials and technologies. These devices are able to influence the overall design of the façades of tall buildings producing very different visual effects. The different technical solutions seem to fit better in specific contexts of the city. For this reason the study of the environment in which the building is located and a very thorough understanding of the currently available technologies would be very important. Bibliography 1. AEDAS. (2012). Abu Dhabi Investment Council Headquarters. www.aedas.com 2. Altomonte, S. (2004). L’involucro architettonico come interfaccia dinamica: strumenti e criteri per una architettura sostenibile. Firenze: Alinea. 3. Decker Yeadon. (2010). Homeostatic Façade System. http://www.deckeryeadon.com 4. Gasparini, K.; Premier, A., editors. (2009). Progetto unitario: esercizi di pensiero e di realizzazione per un’architettura verticale. Verona: Knemesi. 5. Kinetura. (2008). Kinetower®. www.kinetura.com 6. Premier, A. (2012). Superfici dinamiche: le schermature mobili nel progetto di architettura. Milano: Franco Angeli. 7. Premier, A. (2012). “Dynamic façades and smart technologies for building envelope requalification” in Gasparini, K., editor. Media environment. New technologies and tools for the communication and valorisation of the built environment. Verona: Knemesi. pp. 65-69 8. Ritter, A. (2007). Smart Materials in Architecture, Interior Architecture and Design. Basel: Birkhäuser. 9. Scheerbart, P. (1914). Glasarchitektur. Berlin: Verlag der Sturm. 10. Taut, B. (1929). Die neue Baukunst in Europa und Amerika. Stuttgart: Hoffmann 11. Zennaro, P. (2009). Architettura senza: micro esegesi della riduzione negli edifici contemporanei. Milano: Franco Angeli. Alessandro Premier

Iuav University of Venice E-mail: [email protected]

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