Proceeding  of  International  Conference  on  Adaptation  and  Movement  in  Architecture  (ICAMA2013)  Ryerson  University,  Department  of    Architectural  Science,  Toronto,  Canada,  11-­‐12  October  2013  

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Implementation of Kinetic Systems in Architecture: A Classification of Techniques and Mechanisms

Appropriate for Discreet Building Parts

Konstantinos-Alketas Oungrinis 1 1 School of Architecture, Technical University of Crete, 127 El. Venizelou street, 73133, Chania, Greece,

kugrinis@gmail.com

ABSTRACT

“What to Where?” is a famous motto in the fashion industry that addresses the selection of clothes and accessories that people should wear according to their location and activity. It seems strangely relevant, though, with the aims of adaptive design as they too refer to movement, fitting, aesthetics, and “behaviour”. Fashion is quite aware of these features while architecture is just tackling them selectively. The issue of movement in particular has been an inspiration to the work of a generation of architects and recently a strong parameter in form-finding methods. Real application, though, still seems out of reach, even if there is a large number of built examples with kinetic elements, many of which were met with significant media exposure. However, the vast majority of practitioners do not know how to implement kinetic systems in buildings and believe it to be a Herculean task.

This paper is heavily based on the author’s analysis of more than 120 paradigms of transformable-adaptive structures in various scales and with diverse utilizations. The analysis resulted in a classification that aims to act beneficially in the field by introducing engineers and architects to a series of principles and techniques appropriate for implementing kinetic systems for discreet building parts. The basic criteria that guide the classification is the type of movement required, the scale of the building as well as the scale of the kinetic elements, the transformability principle employed, the ability for a secure fit and the resulting aesthetics. The categories of the building components where transformability can be applied are “structural support systems”, “building skins”, “roofs”, “floors” and “interior partitions”. The classification also includes transformations of peripheral parts like in the cases of “expanding spaces” and “spaces within space”, as well as adaptable autonomous dwellings like “micro-spaces” and “emergency shelters". Moreover, the paper lists the benefits and the disadvantages associated with the application of certain mechanisms and techniques to specific building parts, with further suggestions for future experimentation.

The presented research project provided the groundwork for the creation of an online educational database, available to anyone who wishes to carefully study the architectural and technological advancements that kinetic architecture impregnates.

Key Words: Transformable architecture; kinetic systems; building techniques; design

methodology; adaptation implementation strategy.

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1. INTRODUCTION

The intuitive processes and the choices that architects follow cannot be described, being a subjective path that characterizes a creator and her/his style. The construction approach, on the other hand, can be described thoroughly, and it has to be, in order to establish a concise and measurable framework of techniques toward the materialization of the project. The "know-how" of the "what-to-where" set can form a database that will provide architects with a foundation (a starting point) to investigate suitable solutions for their design, achieving the desired combination of the chosen phenomenological effect with the application of the appropriate technique(s).

The construction approach in transformable design is an issue of greater importance than in the case of a conventional building because there are issues of much greater complexity addressed and the cost of implementation is significantly higher, leaving no room for vagueness and on-site solutions. The specialty issues revolving around each choice could be divided in three distinct areas:

- The physical changes of the overall form, or parts of it, should be in correlation with the overall 'image' the architect requires to achieve.

- Transformations addressing functional issues, which must be resolved and facilitated, should be materialized in such a way so as to avoid hindering the activities they aim to benefit.

- According to each activity and the people’s participation in it, the methods that the architect employs should be considered carefully under the notion of reducing the feeling of the uncanny. The psychological impact of transformable elements is, perhaps, the most critical issue since an occurring discontent will lead to a non-usable space.

These constitute the three foundation rules according to which a classification of "what-to-where" is formed regarding the appropriate design principles and procuring techniques to address the materialization of different adaptable structural elements in architectural projects. Further classification analysis is leading to differentiations relevant to the time/stage of intervention, use, scale and cost that optimize the final selection from the solutions available for implementation. The classification is formed around the types of structural elements in an artificial environment. These are: 1. Building components

- Structural Support Systems - Building Skins - Roofs - Floors - Interior Partitions

2. Peripheral Parts - Expanding Spaces - Space within Space

3. Autonomous dwellings - Micro-spaces - Emergency shelters (This category is not a structural element but holds a discreet value as an

autonomous entity, either as a whole or as a part, that may even exist inside another building as part of it).

The research is quite extensive but in some categories the fabricated examples are scarce. In this case, the paradigms are conceptual projects and hold little implementation value, but they still show a design direction and a construction potential that deserves to initiate a discourse around them. The principles are taken from the author’s own classification system. [1]

2. BUILDING COMPONENTS

All building components act in a specific way, complementing each other, to create a whole that satisfies the design intentions. In transformable design the kinetic systems may be integrated into all

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or some building components, in order for the whole to exhibit the anticipated overall behaviour in the most efficient way.

2.1. Structural Support Systems

The structural support system forms the core of any building, affecting its behaviour. As Peter Rice many times stated, every design, consciously or not, includes a structural support design direction. In an architecture of motion there are some basic categories.

The first one involves whether the structural support system is visible or not: a. The structural support system is visible in the exterior of the building. Visible support structures

affect greatly the morphology of a building and produce more ‘mechanical’ aesthetics, promoting an image where a weave of elements act together.

b. The structural support system is hidden beneath the building envelope and may not be visible even in the interior. Hidden support systems have a very small role in the overall aesthetics of a building, if any. These buildings usually emphasize a form created by surfaces.

The decision for a visible or a hidden structural support system is of prime importance as it is essential for the overall morphology and the type of cladding that best fits the design. It is evident that as the support system becomes more flexible, cladding and supporting electromechanical utilities must follow that flexibility.

The second category involves the selection of an active or a passive kinetic system to address transformability:

a. Active kinetic systems take a leading role in changing the useable spaces and the overall form of the building in the core level. These changes affect the exterior of the building, all interior spaces and building components. They are quite expensive and moreover, they have not yet been properly evaluated to lead to reliable conclusions.

b. Passive kinetic systems do not intend to affect the operational mode of a building but only to enhance its structural ability. The responses affect only the characteristics of the structural system, enhancing it according to stresses and loads applied in various conditions. These systems do not produce intense transformations and are usually aimed to reduce the factor of movement and its impact in the support system. They have started to spread widely, usually in large emblematic structures, primarily as regulating systems for increased safety.

These two classes are not necessary in contradiction, as they can be combined. However, designers should state which one is their priority in order to follow the appropriate design path. Overall, the flexibility of a system works favourably to its proper adjustment either to applied stresses and loads, or to operational and functionality issues relevant to the use of the building. On the other hand, it has a significant downside regarding the precise insulation of the building. The flexible attachment of the cladding elements upon the support system presents a reduced ability to regulate the environmental conditions that affect the building. Noticeably, as the requirement for intense flexibility rises, the best-suited techniques are the ones where the support system and the cladding are merged to a single element, like in the case of pneumatic and transergetic structures. [2]

The advancements in the domain of material science enhanced the properties of structural fabrics and their ability to manage energy issues, tactility and strength in a few microns, providing a solution that addresses the issue of flexible cladding and increasing in many ways the efficiency of the whole structure. Among the prescribed benefits one can pinpoint the smaller ecological imprint, the reduction in the amount of material used, the reduction in the weight load, the increased flexibility, the decrease in the time it takes to operate between transformation modes and, finally, the ability to provide a safety net.

The principles and the techniques that can be employed in the case of active systems are: Aero-pneumatic. It encompasses one of the most prominent technologies while its origins

as an experimentation field in contemporary transformable architecture precedes all other. There many obvious benefits revolving around lightweightness, like freedom of form and easy deployment. However, there are equal obvious disadvantages, mainly involving

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control, consumption of energy and high susceptibility to air conditions. Recent research directions aim to cover these weaknesses with a number of supporting techniques. Examples can be found in the works of the Hyperbody Research Group (HRG) at TU Delft.

Transergetic. In the author’s opinion, this is the most prominent principle for the future of applied transformability in architecture, especially in combination with pneumatic elements. This opinion derives from the fact that it is the most efficient support system produced by engineering, as it optimally assigns the loads to the appropriate members that exhibit the ability to handle them and, moreover, it can exhibit precise control while allowing for great transformations. The evolving parametric computational tools promise to handle the great inherent complexity. The most prominent examples in this approach are the HybGrid project by Sylvia Felipe Marzal and Jordi Truco Calbet (Figure 1), the WhoWhatWhenAIR: Interactive actuated kinetic tower by Philippe Block, Axel Kilian, Peter Schmitt, John Snavely and the works of Tristan d'Estree Sterk.

Figure 1: Through a biomimetic approach, Hybgrid aims to create a system that produces non-predetermined

forms by changing the relations between the nodes of the structure.

Scissors mechanisms. This principle provides the ability of transformations in great

extends of synclastic and anticlastic surfaces. It is widely applied in deployable furniture as well as in portable paradigms of architecture. A large number of cladding methods have also been tested.

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The leading architect in this field is Chuck Hoberman (Figure 2). His research has elevated it to the status of a well-documented and tested technique for the application of kinetic support systems.

Figure 2: The Expanding Video Screen by Hoberman Associates, in partnership with Innovative Designs.

Hybrid. This combination of techniques will probably evolve to give sophisticated solutions in

the near future. The "Tensairity" [3] technique, for example, is trying to combine the benefits emerging from pneumatic and tensegrity methods. With modifications, this hybrid solution can act as a platform for the development of kinetic structural support systems.

The principles and the techniques that can be employed in the case of passive systems are: Transergetic. Some allowance in the relations of cable and rod members could lead to a

passive responsive system. A well-documented study around a self-stiffening system was conducted by Oscar Sirovich Saar at the University of Jerusalem. [4]

Pneumatic. While this technique has the ability of intense form changes, there are applications where the 'muscles' can act only as external stabilizers. A characteristic example is the Airtecture project by Festo.

Shock absorbers. This technique does not apply to any principle since it is mainly technical and relies solely on equipment. There are two types identified:

Fluid friction. This system is used widely nowadays in the construction of bridges and in skyscrapers as well. Its application in support systems helps absorb resonant energy thus providing a significant benefit in the structural stability and failure avoidance. The Rio-Antirio Bridge project by Berdj Mikaelian is an example.

Tuned mass dumpers. This system is designed specifically for high-rise buildings, in order to reduce the oscillation that can lead to serious destabilization. Buildings with no oscillation effects do not require such a system. The Taipei 101 project by architect C. Y. Lee is an example.

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All these systems have a common goal and their future evolution is largely dependent on their resemblance to a 'natural' system. [5] In this perspective, for a system to be identified with the potential to be widely applied it should exhibit increased loading capacity in relation to its mass, its ability to strengthen specific points where failure may occur and its easy, low-cost maintenance.

2.2. Building skins: cladding-façades-envelopes

The element that has the most prominent effect in transformability, as it is perceivable from a distance and from different perspectives, and has the most significant effect in the environmental imprint is the exterior envelope. The building’s surface is the threshold where all relations between the interior and the exterior are regulated. There are a lot of factors to be mediated through the skin and therefore so many reasons exist for a transformable façade to handle all these concurrencies and produce many different outcomes [6].

The high value in communicating the symbolic layer of architecture rendered the façade an 'icon' that added extra value upon the already critical role of the 'regulator'. Within the urban scale, the Information Technology (IT) revolution rendered façades as active projections, endorsing more vivid solutions. These factors indicate that there are a lot more to come in order to enhance the aforementioned characteristics as to where the 'limit' of buildings is negotiated.

The most common principles and techniques used in building skins examples so far are: Folding rigid surfaces. This is one of the most common principles used, since its geometry

allows for adequate sealing with supporting frames and it is fairly easy to control. The outcome, from a phenomenological perspective, can be quite evident and can transform the sense of a place enough to allow diverse aesthetics. The Gucklhupf project by Peter Woerndl is an example showing how simplicity can achieve an impressive outcome.

Folding flexible membranes. This is one of the oldest and most widespread principles. It provides adequate flexibility and rigidity but it is limited to small-scale interventions. Applications that seem to use folded linear elements in reality use this technique in order to achieve insulation. The Markies project by Eduard Boechtlink is an example.

Sliding. This principle can effectively allow a façade to work on layers. It is quite effective, providing adequate sealing. It can also work as part of a larger system. The Sliding House by DRMM shows this potential (Figure 3).

Scissors mechanisms. This technique can only be used when the façade is fixed on a different support system. The Hoberman Arch project by Hoberman Associates is an example.

Pneumatic. The lightweightness of inflatable elements in combination with the technological advancements that render them efficient as environmental regulators makes this technique one of the most prominent for the future of façade applications. The Muscle façade project by the HRG is a system that provides form, lighting and color changes, moving toward the direction of a hybrid between kinetic and media façades.

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Figure 3: The Sliding House by DRMM.

2.3. Roofs

The roof of a building is considered the closing element of the exterior and is the structural element that most cultures describe it with a synonym of the word 'protection'. This feature renders a roof as an 'entity', a 'shield' that protects from the weather and other harmful elements. In this nature, it is rarely something transformable. In public buildings, though, this notion could be overcome. It was the Colosseum the first building that is said to employ a form of an adaptable roof [7].

Today stadiums, theaters and government buildings are the most common examples with transformable roofs. The techniques used are:

Sliding linear. The usually great mass that has to be moved allows for little techniques to be employed. Sliding is one of the easiest and most tested, facilitating gradual opening. The Veltins Arena project by Hentrich, Petschnigg and Partners is an example.

Sliding axial. Contemporary paradigms employ axial movement to create a more intricate effect as a roof deploys, promoting the symbolic and communicational aspect. In the Qi Zhong Stadium project by Mitsuru Senda the roof opens up like a lotus flower.

Tensile. This is the oldest principle regarding transformable roofs and it is applied in all scale range. It exhibits a lot more flexibility than the previous classes but it is much harder to procure the proper force to keep the fabric effectively tensioned. The Eco-29 project by FoxLin is an example that combines projections to augment the kinetic sensation (Figure 4).

Scissor mechanisms. This technique brings the benefits of the previous classes together. It can be deployed to any desirable degree with precision and cover large areas. The Iris and Expo domes by Hoberman Associates are some distinctive paradigms.

Roofs, in general, allow for experimentation with many techniques, as they have few restrictions of possible forms, but their performance under wind and snow loads is critical for their successful application.

Figure 4: The Eco-29 project by FoxLin.

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2.4. Floors

A structural element that is quite difficult to exhibit transformability is the floor along with any levels where activities are positioned. The characteristic that hinders such an option is the fact that it must always be leveled in order for people to perform there for long periods of time. If a floor is required to exhibit transformability then the principle used must exhibit a direct sense of safety. This is the reason why robustness is essential for kinetic floors, as well as the ability to define clearly the end of the useful surface. The techniques employed for this structural element are:

Folded rigid surfaces. The sizes allowed by this principle and the know-how available make this technique easily applicable. The Bloomframe project by Hofman Dujardin is an example (Figure 5).

Folded linear elements. This technique can create such diversity that it has a potential to create 'scapes' but it has a serious deficiency. A way to cover the openings between members is crucial otherwise it may be unsafe to use. The LeisuratorTM project by Marco Pastore and Valentina Sabatelli is an example.

Sliding linear. This a straightforward solution where deployable elements are hidden by layering. It facilitates the potential of moving large scale surfaces. The Sapporo Dome project by Hiroshi Hara has the ability to relocate the sport’s field.

Sliding axial. Rotation is quite known as a practice and it is commonly employed in spaces with a vantage point of view, as rotating platforms with the ability to enjoy a 360o scenery. The Rotorhaus project by Luigi Colani is a very interesting example promoting spatial economy.

Suspended surfaces. This technique describes a potential rather than an application. It derives from the adjustable acoustic roof panels and the sketches of Heino Engel.

Figure 5: The Bloomframe project by Hofman Dujardin.

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2.5. Interior Partitions

The basic characteristic of this category is that it has the fewest restrictions and requirements. Interior partitions, in the most demanding situation, require high acoustic and adequate thermal insulation. But even these features are many times of no importance, rendering this zone of application a "free-for-all" ground for all techniques to be deployed. The reduced insulation requirements allow for all principles and techniques to be used, to appropriately accommodate different uses. Each principle used has a very direct influence to the overall experience of space and plays a catalytic role in the process of getting accustomed to it. The most common techniques are:

Sliding. Perhaps this is the most common technique used for sliding walls or even moving individual elements to produce diverse settings. If these elements are big enough, they also fall into the «space-within-space» class that will be presented later on. The URhouse project by the HRG combines sliding and folding to achieve a wide range of spatial configurations, where the elements could be moving in real time by the user (Figures 6-7).

Folding. All folding principles can be employed, as they are easy to apply and easy to maintain. The Softwall project by Molo design is a product that can alter a space significantly in an easy but aesthetically intriguing way.

As a general rule, the decision affecting the materialization of adaptable interior partitions is mainly a design experiential issue and much less a structural problem.

Figures 6-7: The URhouse project by the TU Delft Hyperbody Research Group.

3. PERIPHERAL PARTS

In many cases the requirements for a solution leads to practices that do not fall into the category of a building component but act as a peripheral part that can only play its role when attached to or exist within a certain environment. These 'parasites' usually act symbiotically with the main structure, ascribing extra abilities to space for additional uses or features.

3.1. Expanding Spaces

This is a practice that blurs the limits of a building with elements that stick out or disappear again in the overall volume. They are called with different names in regard to the context within which they

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were developed. This is not a new practice, but in the recent years it has become more sophisticated and it is exhibited as something worth promoting.

The prevailing benefit is the movement of these elements as complete systems that require little care and in many cases they do not from a perfect fit to the main structure. Usually this practice works in two phases, open-closed, but it can be applied as a gradual expansion. The most appropriate techniques are:

Sliding/rolling. Either attached, suspended or on tracks in the ground, spaces can slide in positions that provide additional features to support the activities of people when needed. The Fahrt in Grune project by Kalhoefer-Korschildgen exhibits this technique in the purest way.

Folding. All folding principles can be employed. A number of additional spaces can be folded within walls or can act as interior separators. The Maison Valise project by Petetin-Gregoire is an interesting urban pop-up project that can fit to any environment.

Nesting. This technique differs from the others in this class, mainly because it can be used to deploy a whole element as well as individual small parts that are crucial for performing a certain activity. In this sense, equipment parts come out or disappear in the walls according to space usage. The Vinyl Milford House by Alan Wexler theatrically exhibits the technique of nested accessories (Figure 8), as well as the works of the architectural practice Lotek.

Figure 8: The Vinyl Milford House project by Alan Wexler.

3.2. Space within Space

This practice deals with the outer shell as a protective membrane while the interior space facilitates uses which are organized through individual elements that move freely around the protected space. This type of spatial organization resembles natural and multi-agent systems working in a protective shell. It is considered a practice that allows significant freedom and can provide a series of different scapes, topologies and relations between elements that create discreet settings for specified

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uses. It considered simple structurally and allows for a wide number of variations and adaptations. The prerequisites are a flexible infrastructure or self-sufficient units that carry all necessary utilities upon them. The principles that work better with the aforementioned constraints are:

Free-sliding. This is the prominent technique with recorded examples from as early as the 1960’s. The elements can be arranged in may ways and can relocate with ease. They can produce stand alone settings or clusters. The Naked House project by Shigeru Ban is a distinctive example. If a folding element was additionally employed as a technique, it would allow the modules to collapse and then ‘disappear’, providing more versatility to the whole system (Figure 9).

Pneumatics. In the same manner, pneumatics can act as rapid deployable enclosures, either in specific places or supported by a moving mechanism. The Foxy Restaurant project by Michael Fox is an example that can act as a prototype for scaled up modules to accommodate the proposed role.

Figure 9: The Naked House project by Shigeru Ban.

4. AUTONOMOUS DWELLINGS

These classes represent autonomous buildings that are mainly designed as stand-alone structures, small in size, highly mobile and flexible. They have a goal to exist as extensions of the human body or facilitators that can create a small useable protected area. They can address issues of emergency or not, although in many cases they can be employed in both occasions.

4.1. Micro-spaces

This category addresses one of the oldest questions regarding an efficient, protective outer shell in optimal scale. Something larger than clothes, fitted and tailored to the body and adjusted per activity, while smaller than a normal house and at the same time robust in structure to provide adequate protection.

Contemporary elaborate design efforts aimed in the creation of semi-cyborgian approaches, highly connected to IT, advanced materials and intricate design. [8] This trend did not hinder, though, the production of simple and ingenuous design solutions that led to more approachable and feasible materializations. These projects are mainly used as temporary shelters. They fit in this category due to their characteristics of high portability and high adaptation. The most fitting techniques are:

Folding flexible membranes. Based on the traditions of tent design, the folded fabric approach has produced many solutions regarding small emerging dwellings that exhibit adaptability and diverse uses. Characteristic examples in this approach is the Parka/Air Mattress project by Moreno Ferrari, a sophisticated example of ‘clothes-turn-to-shelter’ and the Basic House project by

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Martin Ruiz de Azua. Pneumatic. This technique is employed because air is an omnipresent 'byproduct' of many

activities. If it is used creatively, then a shelter emerges. The ParaSite project by the artist Michael Rakowitz provides pop-up shelters for homeless people (Figure 10).

Figure 10: The ParaSite project by Michael Rakowitz.

4.2. Emergency Shelters

The basic use for the design products of this category is to provide safety in extreme conditions. Their common characteristics are high portability, rapid deployment and adequate level of protection even on the move. [9]

There are two general types of structures: Deployable (rapidly) that try to prevent or reduce the impact of an emerging catastrophe

and create a space for immediate protection or cover. They do not try to create a shelter. Shelter providing for the ongoing strenuous conditions that follow a disaster.

The emergency constructs of the first category can not be considered architecture per se but their presence and their influence affects space and the way people perceive it. It is essential that those constructs perform precisely as planned to protect lives and secure their survival as they wait for the rescuers. Only rigid surfaces and pneumatics can be used as basic structural elements, supporting rapid deployment. An example of this type are the earthquake airbags.

In the second category, the emergency constructs are required for the creation of habitats that are mobile, adaptable to different landscapes and strong enough to withstand conditions for at least six months. While the prime function of such a habitat is liveability, habitability should be the final goal. Transformability addresses this issue by creating environments that hold extra qualities for the everyday life. Furthermore, the potential of relocation and protection from secondary disasters should also be employed. An example for this technique is the Eco–Pop project by Konstantinos-Alketas Oungrinis and Marianthi Liapi (Figure 11).

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Figure 11: The Eco_Pop project by Konstantinos-Alketas Oungrinis and Marianthi Liapi.

4. CONCLUSION

The implementation of kinetic systems can be greatly benefited from an holistic approach that would avoid problems and produce seamless solutions. This paper presents a research that aims to create such a tool, to allow the investigation of a problem by examining many possible solutions and design directions from a list of examples. This brief summary presents mainly the need for a well-documented classification of paradigms that can be used as a reference for implementing kinetic systems in specific structural elements and act gradually as a platform for sharing 'know-how' techniques that will facilitate the further application of transformable design.

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The analysis results and the observations of this research direction were compiled for the creation of an online educational database, available to anyone who wishes to carefully study the architectural and technological advancements that kinetic architecture impregnates. For more information please visit, get inspired and experiment with www.transformabledesign.com.

REFERENCES

[1] Konstantinos-Alketas Oungrinis, (2006), Transformations: Paradigms for designing transformable spaces, pp. 16-21, Harvard GSD Design and Technologies Report Series, Cambridge, MA.

[2] Konstantinos-Alketas Oungrinis, (2007), "'Sensponding’ architecture: Towards a holistic approach to transformable design", in Proceedings of the "Tectonics making meaning" International Conference. Available at http://www.stud.tue.nl/~cheops/tectonics/pdf's/Oungrinis.Konstantinos-Alketas.pdf (Retreived 20 May 2013).

[3] Rolf H. Luchsinger, R. (2004). "Pressure induced stability: from pneumatic structures to Tensairity,®" Journal of Bionics Engineering Vol.1 No.3, pp. 141–148.

[4] Oscar Sirovich Saar, (2000), " A new type of hardening structure," in Felix Escrig, and Carlos Alberto Brebbia, (eds.), (2000), Mobile and Rapidly Assembled Structures III. (Advances in Architecture), WIT Press, Southampton, pp. 113-124.

[5] Steven Vogel, (2003), Comparative biomechanics: Life’s physical world, p. 441, Princeton University Press, Princeton.

[6] Christian Schittich, (ed.), (2001), In detail. Building skins: Concepts, layers, materials, pp. 10-25, Birkhäuser, Basel; Boston; Berlin.

[7] Bill Addis, (2007). Building: 3000 years of design engineering and construction, p. 47, Phaidon, London; New York, NY.

[8] Amir Bonjar, (2005) "Earthquake airbags, new devices to save lives in earthquakes, tornados and similar disasters resulting from building crashes," American Journal of Applied Sciences 2, pp. 774-777.

[9] Paola Antonelli, (2005), Safe: Design takes on risk, The Museum of Modern Art, New York, NY.