1 INTRODUCTION Traditional approaches toward energy efficient and ecological friendly buildings address optimization of the building materials and systems of a given build-ing envelope. Geometrical changes of the building morphology happen during design and optimization processes, however, few designs stay convertible in their later phases, and even less offer short-term flexibility during operation. If so, then the flexibility normally applies to automatically operated window and door openings, radiation sensitive shading de-vices and adaptable HVAC-Systems. Very few ap-proaches consider the transformation of the overall building shape, be it an Euclidian operation (such as rotation) or an Non-Euclidian transformations, such as NURBS-based skewing, squeezing and distortion. One well-known example for Euclidian movement of a whole building envelope is the Heliotrop House in Freiburg by Architect Rolf Disch (Disch 1994) il-

lustrated in Figure 1. This highly-insulated building was constructed in 1994, and features a centralized plan, where the envelope can be rotated around its vertical central axis. While rotation of buildings was per se not a new development, this project can be considered as the first combination attempt of rota-tion and thermally optimized construction, as rota-tion was realized to pursue the sun position for max-imizing solar gains. However, it has to be said, that some of the earlier attempts of rotating building were realized with the intention of minimizing sun penetration. An example for this is the rotating alu-minium house in Snow Creek, Palms Springs, erect-ed by aerospace engineer Floyd D’Angelo (D’Angelo 1963) as depicted in Figure 2. This pro-ject is for its time especially mentionable, as “In or-der to rotate the home […] D'Angelo adapted a de-vice from his product company that was made to open and close aluminum loovers. Originally, D'An-gelo powered the mechanical equipment through a

Ecological Ballet - A design research towards environmental-reactive, adaptive architectural design.

B. Sommer & G. Moncayo Energy Design, Institute of Architecture, University of Applied Arts Vienna

U. Pont Department of Building Physics and Building Ecology, Vienna University of Technology

ABSTRACT: The present contribution reviews a set of architectural design studies that have been developed under implementation of adaptive – thus moveable – structures. The conceptual ideas behind the different de-sign approaches are different, but all designs share the idea of interaction between the environment, the user and the building skin. While architectural theory and history show many examples of conceptual approaches toward moving, changeable or interactive buildings – for instance the walking cities of the Archigram Group – few realizations have been made, and even fewer approaches toward sustainability in these adaptive struc-tures were conducted. The design concepts in this study, however, pursue the task to develope performative, interactive architectural concepts while following the necessity of highly energy-efficient building skins. Each project follows a procedural design process influenced by inspirations from natural (for instance prevail-ing wind direction) but also anthropogenic (for instance Japanese origami paper folding techniques) origin, and links these inspirations with thoughts for energetic, ecologic and environmental architecture. This proce-dural workflow in design led to five innovative concepts of different scales. These concepts were not only an-alyzed toward their potential realization, indeed they were constructed as scaled models that could react to environmental influences from outside or certain user inputs. These models use single-board microcontrollers and small electrical actuators to change their envelopes. The present paper presents the ideas and concepts of the designs, illustrates the realization of the scaled and fully operable models, and analyzes the potentials (and potential problems) of full-scale realizations. Furthermore, the projects are documented from the viewpoint of building physics and energy design. All projects were created in a specialized design studio at the University of Applied Arts in Vienna, and were shown in a one-day performance in the Museum of Applied Arts Vienna (MAK).

photovoltaic cell on the roof which powered the sys-tem's rotation arc.” (ModernHomesLosAngeles 2014). Further well known examples of Euclidian transformation of building geometry include Hoberman Associates, who realized an Euclidian transforming curtain as a stage installation at the Salt Lake City Olympics Medals Plaza in 2002 (Edupuganti 2013, Figure 3), as well as the infra-structure building of the Falkirk wheel (completed in 2001, designed by Nicoll Rusell Studios, Figure 4, Falkirk Wheel 2014). It has to be noted, that the lat-ter two examples, as many other “moving” struc-tures, are not directly connected to the energy dis-course.

Figure 1, Heliotrop House. Rolf Disch (pictures: www.rolfdisch.de (left) and www.ecofriend.com (right).

Figure 2. D’Angelo House, Snow Creek, Palms Spring. A ro-tating structure for minimizing solar penetration (picture cour-tesy of B.Sommer).

Figure 3. Hoberman Arch, Salt Lake City, different transfor-mations (pictures: S.R. Edupuganti 2013).

Figure 4. Falkirk Wheel, Nicoll Rusell Studio,(pictures: https://www.youtube.com/watch?v=n61KUGDWz2A&feature=kp). There are fewer examples of non-Euclidian geome-try transformations, for instance: (i) Frei Otto’s In-flatable Marquee 1979 (Häuplik et al. 2007); This study of Frei Otto shows a growing and diving changeable pneumatic construction; (ii) Dynamat,

Simon Conolly and Mark Fisher 1971 (Häuplik et al. 2007); This project’ structure is as well based on a pneumatic principles showing two layers of inflata-ble cushions, thus allowing for a fully controlled transformation of non-curved into single- and dou-blecurved forms. With this principle both synclastic and anticlastic forms can be realized. (iii) Hyposur-face projects of the dECOi architects (dECOi 2014): These projects resemble interactive reacting, physi-cally moving screens, based on indivually controlled pistons; (iv) Michael Fox‘s Flock Wall working out with fishing lines and reels to change form (Fox 2009); (v) The Kiefer-Technik Showroom by Gisel-brecht and partner ZT (2008) is remarkable, as it is one of the few realized full scale application of a controllable three-dimensional surface close to the afore-mentioned hyposurface projects, implemented as a shading device. (vi) The concepts of interactive architecture, as defined by Oosterhuis (2013, 2014) and his Hyperbody research institution have been – until now - rarely realized. The design principles of Hyperbody do not clearly tackle the question of en-ergy performance as a first prerequisite, but easily could adapted for this purposes.

Most of the concepts of the Non-Euclidean pro-jects targeted interactive design strategies in the first place. It is remarkable that Non Euclidean geome-tries seem to be an intrinsic approach when it comes to the realization of interactive architecture.

In this contribution, five design studies are pre-sented and reviewed, which combined interactive transformation of building envelopes, similar to the above mentioned, with energy performance consid-erations. These five designs are presented and dis-cussed in the subsequent sections.

2 FLORAL SKIN This approach (Students: M. Lichtenwagner and C. Yönetim) was based on an Origami pattern, and fea-tures an adaptive building envelope, capable of changing the volume to surface ratio (compactness). Additionally, parts of the skin are capable of being rotated toward a sun-position for optimal usage of insolation with Photovoltaics. The structure features 4 different surface types: (i) black surfaces resemble solar collectors with a high degree of solar absorp-tion to produce heat; (ii) grey surfaces symbolize Photovoltaic panels for generation of electrical pow-er; (iii) blue surfaces symbolize transparent parts of the building envelope; (iv) white surfaces are opaque with a high degree of reflection, as shown in Figure 5. The expanded structure is optimized for winter season and resembles a closed air tight build-ing skin. The collapsed structure one the one hand totally folds away the black absorbing areas and re-duces transparent surfaces, while keeping the high-ly-reflecting as shading devices in place. The PV-cells are in this mode better protected against over-

heating, thus will show a higher efficiency. On the other hand, through collapsing the skin is opened for natural ventilation. Figure 6 shows the manipulation of the model (influencing the photosensors on the surface), while Figure 7 illustrates the folding pro-cess of the skin.

Figure 5. Design principle of Floral Skin (courtesy of M.Lichtenwagner and C.Yönetim).

Figure 6. Floral Skin in winter mode (left) and summer mode (right). Picture courtesy MAK/K.Wißkirchen.

Figure 7. Folding process of Floral Skin. Picture courtesy G.Moncayo. 3 BREATHE This model (Students: M. Urschler, R. Portillo) takes the airflow into the building as a design influencing parameter, and features a mode for cold and a mode for hot season. Changes in shape, realized with a lung-like folding structure, allow the building enve-lope to be expanded in summer (increased volume) and decreased in winter times (smaller volume) to reduce the heating demand and necessity of precon-ditioned air for ventilation. The underlying principle influences the characteristic length of the object, be-ing optimal for the prevailing season. Independent of the season and state of compression, the structure is capable of “breathing”, which means peristaltic movements of the folding structure to force ventila-tion. The realization as a model was done via origa-

mi-like folded paper structures, and the actuator were three electro motors for rotation influenced by lighting levels in the area of the three structure’s en-trances. The control scheme would – in winter case – try to bring pre-warmed air from sun-exposed are-as into the interior, while in summer case would try to funnel cool air from the shaded areas into the building. Figure 8 illustrates the applied construc-tion, while Figure 9 shows a visitor manipulating the shading sensor.

Figure 8. Breathe (courtesy of MAK/K.Wißkirchen).

Figure 9. Breathe (courtesy of G.Moncayo).

4 KALEIDOSKIN

This project (Students: B. Chompff and C. Wunder-lich) is about efficient use of passive energy re-sources such as solar gains and natural ventilation. The skin performs according to the user require-ments and preferences during occupancy. For in-stance, during occupancy a maximum of daylight penetration could be set as a user defined target. Whenever no user is present within a certain dis-tance, the performance goal of the structure is to maintain a constant indoor climate, e.g. by shading or ventilation. The building’s envelope is designed to remember user preferences and towards learning and adjusting its behavior to specific users. This pro-ject was realized as a technical 1:1 mock-up of the real design, thus it works exactly as intended for real world. The interaction with users is performed via proximity sensors, so that the façade fragment fol-lows the visitors according to seasonal and individu-al preferences. The only difference between mock up and intended design in, that the audience could not manipulate the user preferences (as this is only useful for a limited number of permanent users). The double layered skin driven by rotational actuators creates an infinite number of patterns and gradients between different degrees of transparency on the one

hand, and different permeability for ventilation on the other hand. Figures 10 and 11 show the principle design of Kaleidoskin, while Figures 12 and 13 show the surfaces and proximity sensor and the transformation process.

Figure 10. Design sketch of Kaleidoskin. Courtesy of B. Chompff and C. Wunderlich.

Figure 11. Working Scheme of Kaleidoskin. Courtesy of B. Chompff and C. Wunderlich.

Figure 12. Kaleidoskin, showing the different surfaces and the proximity sensor. Courtesy of MAK/K. Wißkirchen.

Figure 13. Transformation of the Kaleidoskin-Mock Up. Cour-tesy of G.Moncado.

5 JELLY

This design (Students: D. Prost, K. Sitzmann) fea-tures a Theo-Jansen-inspired elegant kinematic form changing mechanism that lifts a curved envelope in wintertime to allow a maximum of sun penetration into the interior, while in summer just lifts the enve-lope at shaded spots to reduce overheating tenden-cies inside. Therefore, a sophisticated control scheme for the envelope was designed. This includes a set of sensing devices, measuring he temperature inside and outside of the structure, as well as the so-lar radiation via pyranometers on different grid points on the surface. In winter case (desired tem-perature inside > outside), Jelly opens the curved envelope to the points of maximum solar incidence, while in summer case (desired temperature inside < temperature outside, see Figure 14), allows for ven-tilation openings, where the solar incidence is at a minimum. This setup allows for a real-time interac-tive adaption of the building skin to the indoor and outdoor climate, not only considering the sun incli-nation, but also cloud cover and seasonal changes. In the scaled model, this advanced control scheme could not be realized, as the model was constructed for a display in a museum (no outside climate im-pact). The impact of the environment was replaced by the audience, which would shade light sensors thus triggering the transformation process of the Jel-ly’s skeleton. Figure 17 shows visitors deliberately amplifying the effect of shading on the model, while Figure 18 illustrates the movement by Jelly.

The challenge of bringing the designs’ complex movement patterns into reality was solved with a ki-netic system driven by a single rotational actuator. The structure allows for more than just one repeti-tive movement pattern, as the rotational movement in the xy-plane has been combined with a translation in the z-axis (compare Figures 15 and 16).

Figure 14. Summer case considerations for JELLY. Courtesy of D.Prost and K.Sitzmann.

Figure 15. Principle structure of JELLY. Courtesy of D.Prost and K.Sitzmann.

Figure 15. Technical Sketches of JELLY. Courtesy of D.Prost and K.Sitzmann.

Figure 16. Technical Principle of JELLY. Courtesy of D.Prost and K.Sitzmann.

Figure 17. Model of JELLY. Courtesy of MAK/K. Wißkirchen .

6 DANCING WITH THE WINDS

This design project was originally intended for the local micro-climate of the city of Hong Kong, and uses (prevailing) wind speed and direction as an ac-tuator for change of form of the building. Mild and slow winds are used for chilling the building, thus the building turns its broad side to the wind, while strong winds make the building show its narrow sides to reduce wind pressure stress on the façade elements. If outside conditions are fine for wind chilling and natural ventilation the building enlarges its surfaces toward the wind direction, thus using windward and leeward effects to control pressure differences for cross ventilation (Figure 19). A reali-zation of this concept would need a sensing grid (wind speed, temperature, humidity) on the façade of such a structure as well as indoor climate monitor-ing. That way the shape of the tower can precisely respond to different microclimatic states on the fa-cade. The scaled model can be influenced by the au-dience through insufflation. If the airflow is slow, the building will enlarge the surface towards the vis-itor, if the airflow is (too) strong the building will aerodynamically sharpen its form turned to the audi-ence. Figure 20 shows the tower in transformation.

Figure 19. Different pressure and temperature situations turn the tower towards (right) or away (left) from the wind direc-tion. Courtesy of P.Reinsberg and X.Wan.

Figure 18. Jelly (picture courtesy of G.Moncayo).

Figure 20. Tower while transforming. Courtesy of R. Zettl.

7 CONCLUSION & FUTURE WORK

Concept and models show the great possible variety of adaptive design that is just about becoming feasi-ble on a broader, affordable scale. It is worth to look into these concepts, as with the next and necessary step of energy efficient architecture, we will have to question architecture not only on the component level, but we will have to question the very idea of what architecture is and what it can do for us.

Future work in this specific field should address on the one hand the realization of such concepts in 1:1 mock ups or small buildings accompanied by a strict and rigorous monitoring and documentation, while on the other hand the evaluation of the conse-quences and impact on energy demand, overheating tendencies and climatic adaption of such flexible structures should be examined with convenient tools, like for example dynamic thermal simulation.

From a cultural perspective the design focus shifts from the design of an absolute form to the de-sign of a transformation and movement. Thus the dimension of time becomes part of a discipline that was – until now – strictly and solely determined by the dimension of three-dimensional space.

8 ACKNOWLEDGEMENTS

This contribution illustrated architectural design work of the following students of Architecture of the University of Applied Arts, Vienna: B. Chompff, M. Lichtenwagner, R. Portillo, D. Prost, P. Reinsberg, K. Sitzmann, M. Urschler, X.Wan , C. Wunderlich, and C. Yönetim. These were realized in the Seminar “Energy Design Strategies” of the department of En-ergy design in summerterm 2013.

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