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Article ‘Materials as a Tool’ Design Philosophy Applied in Three Innovative Research Out of Sustainable Materials with Controlled End-Of-Life Scenarios

Hanaa Dahy 1,2

1 BioMat (Bio-based Materials and Material Cycles in Architecture) Research Department at ITKE (Institute of Building and Structural Design) in Faculty 01–Architecture and , , Keplerstr. 11, 70174 Stuttgart, ; [email protected] 2 FEDA: Department of Architecture, Faculty of , Ain Shams University, 11517 Cairo, Egypt

 Received: 21 February 2019; Accepted: 11 March 2019; Published: 13 March 2019 

Abstract: Choosing building materials is usually the stage that follows design in the architectural design process, and is rarely used as a main input and driver for the design of the whole building’s or structures. As an approach to have control over the environmental impact of the applied building materials and their after-use scenarios, an approach has been initiated by the author through a series of research studies, architectural built prototypes, and green material developments. This paper illustrates how sustainable building materials can be a main input in the design process, and how digital fabrication can enable variable controlling strategies over the green materials’ properties, enabling adjustable innovative building spaces with new architectural typologies, aesthetic values, and controlled martial life cycles. Through this, a new type of design philosophy by means of applying sustainable building materials with closed life cycles is created. In this paper, three case studies of research pavilions are illustrated. The pavilions were prefabricated and constructed from newly developed sustainable building materials. The applied materials varied between structural and non-structural building materials, where each had a controlled end-of-life scenario. The application of the bio-based building materials was set as an initial design phase, and the here participated within two disciplines: once as , and additionally as material developers. In all three case studies, Design for (DfD) strategies were applied in different manners, encouraging architects to further follow such suggested approaches.

Keywords: ; sustainable building materials; biomimetic; digital fabrication; closed life-cycle; end-of-life scenarios; green materials; Design for Deconstruction (DfD); bending-active structures; segmented shell

1. Introduction A key feature of architecture is the constant adaptation of external influences such as , climate, and ideologies. Architects have always been eager to develop new concepts, analyze existing problems, and transform them into preferred situations. Architecture is influenced by the changing needs of society. In order to adapt to these demands, there is a constant process of rethinking and improving established typologies. Through innovative new developments, the present spirit of the time (Zeitgeist) is used and formed to find sustainable solutions for the architectural and structural problems of our time.

Buildings 2019, 9, 64; doi:10.3390/buildings9030064 www.mdpi.com/journal/buildings Buildings 2019, 9, 64 2 of 13

However, the constant further development of architecture’s form and function is still continuously achieved by the guidance of a rigid linear design thinking process. This classical is based on a fundamental idea, whose emphasis follows the order: defining the problem, , problem solving, and finally, testing [1]. It was this specific design tool that made it possible to develop most of the current adapted architectural solutions. Although many ecological problems could largely be improved by architecture, the approach of applying specific ecologically friendly materials as a first phase in the design approach is still not largely applied. Due to the need for rapid reconstruction and the high housing shortage, the post-war architecture missed a sufficient discussion with important factors such as the ecological influence and the re-usability after the building elements’ relatively short life cycle, such as for instance building skins that have an approximate lifespan of around 20 years [2]. The still current guiding principle of the industry is anchored in the ‘take, make, waste’ principle [3]. In , this leads to up to 50% non-recyclable construction waste [4]. The construction sector account for more than 35% of global final energy use, nearly 40% of energy-related CO2 emissions [5], and almost 45% of global resources consumption. As the global population will grow from seven billion to almost nine billion by 2040, the demand for resources will rise exponentially so that by 2030, the world will need at least 50% more food, 45% more energy, and 30% more water at the same time when environmental boundaries will have new limits to supply, especially with climate change [6]. Aggregate materials and concrete are currently the predominant building materials by weight used in Europe, which together with high-emission materials such as and aluminum are responsible for the largest share of greenhouse gas (GHG) emissions stemming from the building sector [7]. This paradigm from cradle to grave is no longer feasible, which is why the search for sustainable alternatives is of great importance. The multidisciplinary cooperation among experts from different scientific worlds, including specifically material engineering, architecture, and , as well as possibly biologists, physicists, and others, facilitates huge benefits in setting new circular architectural design philosophies, in which each scientific branch creates an input in the design process. Through this collaboration, another strategy to start the architectural design process may totally differ. In this case, the whole design can start by selecting a specific alternative material, which can be for instance biomass-based, to have the ecologic feedback that is needed, and can be further combined with smart that enable combining the building elements in a way that allows dismantling options for re-use in a later stage. In previous research by Lepelaar et al. [8], the usage of green building materials, especially biocomposites, was considered in the design phase of a pedestrian that was built in the campus of Eindhoven University of (TU/e)in Netherlands. The researchers here worked in a multidisciplinary manner to meet the mechanical requirements as well as the aesthetic ones. In this paper, the freedom of design was offered when specified green building materials were set as a start input in the design process. Here, linear design thinking was not applied, and a new circular design thinking, which started with ‘Materials as a Design Tool’, took place. In this case, the choice of materials—especially bio-based materials—were the starting point, followed by defining and customizing the material properties, applying diverse form-finding strategies using methods, conducting structural analysis and applying digital fabrication technologies to finally prefabricate the building elements. In this case, defining building materials became no longer a subsequent step that follows the linear design phase; rather it became the circular design’s strong . Accordingly, a new design philosophy was established and practiced. The usage of materials’ capabilities as a main input in the design process opened the to the opportunity to develop more sophisticated solutions to address diverse architectural challenges. This design philosophy ‘Materials as a Design Tool’ was combined with concepts that could enable dismantling options, which is referred to as ‘Design for Deconstruction’ (DfD) [2], to be applied Buildings 2019, 9, 64 3 of 13 in the form of small and large-scale mock-up structures. The guiding principles were the applied modular structure . In this case, the focus was on the simple and logic design of the individual components. In order to reach a proper economic impact, the individual building elements should be always prefabricated in a suitable handy size to ensure quick assembly and disassembly [9,10] that do not require special training. Computational form-finding and different fabrication methods can with help achieving structural and material-saving efficiency, which can ensure a positive building balance, hence helping in the reduction of the total CO2 footprint. Therefore, materials cannot simply be regarded as constants. Depending on the desired usage, the selected material should be further developed, customized, and adapted. From the beginning of the design phase, prototyping, mechanical tests, and numerical simulation methods are capable of showing the materials’ capacities and structural performances. Material fabrication is also an important factor, because the manufacturing processes, such as for example extrusion, drilling, or casting also have an influence on both the material behavior and the geometrical variations. The author here strives to find effective ecologic solutions in the building industry through starting with materials as a design tool, where the research and development of sustainable biomaterials is set as a starting point in the architectural design process. The intention is to produce building elements and systems that are CO2-neutral, recyclable, and/or compostable, and could be partially if not completely produced from biomass resources. This could be only achievable through close cooperation between architects, , material experts, and others. One of the applied materials in the case studies was biocomposite fiberboards manufactured from agricultural by-products such as straw, which is the annual rest-over released after harvesting cereal crops, bound by thermoplastic and thermoset organic binders. The fiberboard structure was dependent on the different binders and applied fabrication techniques, which together settled the main architectural design drivers. In the following part, three case studies are analyzed, which highlight the philosophy of ‘Materials as a Design Tool’ combined by the ‘Design for Deconstruction’ concept through individual applications. Each of the three pavilions illustrates the benefits of modular construction with green building materials, which were used as architectural and structural elements. The research pavilions were materialized by different green building materials, whether purely structural or not. Flexible biocomposite fiberboards, [11], elastic wood-based middle-density fiberboard (MDF) boards, and recycled ‘cartoon’ tubes were chosen as the main materials by the author/ to be applied as a start driver in the design process. In each case, the selected materials were customized to the needed structural capacities. In the design process, the focus was on not only the usage of bio-based materials, but also above all an in-depth examination of possible end-of-life scenarios, including re-using the building elements that would increase the validation of the circular bioeconomy, which is another scope that is needed regionally, especially at the European [12]. Biocomposites can act as partial replacement to wood, as well as a partial replacement to the classic fiber-reinforced polymer composites (FRP), as this group of materials lie basically between those mentioned materials (wood and FRP). Accordingly, in order to be able to apply these new alternative sustainable materials, it is always needed to mechanically test them after testing the codes of the relevant materials, such as FRP and wood/polymer composites (WPC), so as to apply standardization and verification to settle how reliable the alternative materials are, according to the frame of Eurocodes, to suit the needed applications in reality. This was especially considered in the first case , which is the largest prototype shown in this paper. In previous work by the author, the improvement of the fire behavior of other developed biocomposites to suit wider applications in architecture was reached [13]. The three analyzed case studies were realized by the Department of Bio-based Materials and Material Cycles in Architecture (BioMat) at the Institute of Building Structures and Structural Design (ITKE) at the Faculty of Architecture and Urban Planning of the University of Stuttgart under the author’s supervision. Buildings 2019, 9, x FOR PEER REVIEW 4 of 13 Buildings 2019, 9, 64 4 of 13

2. Case Studies 2. Case Studies 2.1. BioMat SS 2018 2.1. BioMat Pavilion SS 2018 The BioMat research pavilion 2017/2018 was the result of close cooperation between architects and externalThe BioMat specialists, research in pavilion which architectural 2017/2018 was students the result worked of close hand cooperation in hand with between experts architects from differentand external fields specialists, in a multidisciplinary in which architectural working en studentsvironment worked [14]. The hand 3.6-m in handhigh shell with structure experts from had adifferent span of fields 9.5 m, in acovered multidisciplinary an area of working55 m2, and environment was composed [14]. The of 3.6-m121 segments high shell fabricated structure hadfrom a 2 aroundspan of 9.5350 m, digitally covered fabricated an area of 55and m vacuum-laminated, and was composed curved of 121 segments. segments fabricatedIt was located from aroundat the campus350 digitally of the fabricated University and vacuum-laminatedof Stuttgart in the curved Stuttgart segments. center It was in located Germany. at the campusThe modular of the constructionUniversity of Stuttgartwas made in the of Stuttgart lightweight, city center single in Germany.-curved Theelements modular that construction together wasformed made ofa double-curvedlightweight, single-curved shell. The individual elements that parts together consisted formed of a areinforced double-curved flexible shell. biocomposite The individual material. parts Theconsisted structure of a reinforcedwas supported flexible by biocomposite three crossed material. wooden The structurebeams. This was supporteddesign created by three a delicate crossed aestheticwooden beams.structure This that design was created possible a delicate to dismantle aesthetic and structure reconstruct that was to possiblecreate new to dismantle geometrical and constellations.reconstruct to create new geometrical constellations. The pavilion was a double-curved segmented shel shelll of single-curved wood and biocomposite elements that were interwoven with each other as a 3D fabric, as shown in Figure 11.. TheThe innovativeinnovative curved biocomposites and and laminate laminatedd plates were developed by the author. The bio-based boards thatthat werewere appliedapplied in in the the core core of theof the biocomposite biocomposite laminated laminated panels panels were exceptionallywere exceptionally elastic, elastic, which whichallowed allowed the fabrication the fabrication of extremely of extremely double-curved double-curved surfaces ofsurfaces the final of shell the final construction. shell construction. The elastic Thebiocomposite elastic biocomposite boards were boards through were computerized through computerized numerical control numerical (CNC)-drilled control (CNC)-drilled and cut according and cutto the according set computational to the set computational digital design digital model, desi andgn were model, stiffened and were through stiffened lamination through with lamination veneer withlayers veneer in a vacuum layers in press a vacuum bag, with press no bag, heat with or humidity no heat or pre-treatment. humidity pre-treatment. The resulted The engineered resulted engineeredbiocomposite biocomposite was adapted was to higher adapted stresses to higher and appliedstresses asand a structural applied as component a structural in thecomponent segmented in theshell segmented construction, shell serving construction, as the main serving envelope, as the and main holding envelope, its weight and holding and wind its loads.weight The and stresses wind loads.were transferredThe stresses from were the transferred shell to thefrom ground the shell through to the theground cross-linked through woodenthe cross-linked beams. wooden This 1:1 beams.temporary This construction 1:1 temporary had construction allowed the had testing allowed of the the whole testing developed of the buildingwhole developed under building real systemconditions under for real five conditions months between for five August–December months between August–December 2018. 2018.

(a) (b)

Figure 1.1. (a()a) The The erected erected BioMat BioMat pavilion pavilion at the at campus the campus of the University of the University of Stuttgart; of ( bStuttgart;) Connections (b) Connectionsof the modular of the Design modular for Design Deconstruction for Deconstruction (DfD) system (DfD) in system combination in combination with structural with structural beams. ©beams. BioMat/ITKE—University © BioMat/ITKE- University of Stuttgart. of Stuttgart.

2.1.1. Materials Materials Applied Applied InIn order to create a sustainable bio-based system,system, newly developed bio- bio-compositecomposite panels were testedtested and and adjusted to to enable structural capabiliti capabilitieses that that suited suited their their application in in the the form of segmented shell construction.construction. TheseThese biocompositebiocomposite panels panels were were developed developed by by the the author author in in the the form form of ofnatural natural fibers fibers bonded bonded by thermoplasticby thermoplastic elastic elastic matrices. matrices. The second The second type of type biocomposites of biocomposites applied appliedhere were here wood-based were wood-based biocomposite biocomposite panels that panels were that also were vacuum-laminated also vacuum-laminated by veneer by layers veneer on Buildings 2019, 9, x FOR PEER REVIEW 5 of 13 layersBuildingsBuildings on 20192019 both,, 99,, 64x FORsides, PEER Figure REVIEW 2. The special feature of these materials was their flexibility 5and ofof 1313 elasticity. The elastic fiberboards were bendable in any desired single or double-curved shapes, and thelayers final on shape both was sides, adjusted Figure and 2. Thecustomized special usingfeature three-dimensiona of these materialsl (3D) was veneer their layers,flexibility [15,16]. and both sides, Figure2. The special feature of these materials was their flexibility and elasticity. The elastic Multipleelasticity. material The elastic alterations fiberboards were were developed bendable in thein any form desired of sandwich single or panels. double-curved Different shapes,testing andfor fiberboards were bendable in any desired single or double-curved shapes, and the final shape was thethe reinforcements’ final shape was adjustments adjusted and took customized place in orde usingr to three-dimensiona reach the optimuml (3D) materials’ veneer layers,behavior [15,16]. and adjusted and customized using three-dimensional (3D) veneer layers, [15,16]. Multiple material theMultiple settled material target properties alterations and were performance. developed Ve inneer the formappliance of sandwich had caused panels. a large Different improvement testing tofor alterations were developed in the form of sandwich panels. Different testing for the reinforcements’ thethe developedreinforcements’ biocomposites’ adjustments structural took place behavi in ordeor,r todue reach to thethe optimumoptimized materials’ fiber reinforcement behavior and adjustments took place in order to reach the optimum materials’ behavior and the settled target arrangement.the settled target properties and performance. Veneer appliance had caused a large improvement to propertiesthe developed and performance.biocomposites’ Veneer structural appliance behavi hador, caused due to a largethe improvementoptimized fiber to thereinforcement developed biocomposites’arrangement. structural behavior, due to the optimized fiber reinforcement arrangement.

Figure 2. Double-sided veneering of flexible biocomposite defines a stable curved shape. © BioMat/ITKE – University of Stuttgart. Figure 2. Double-sidedDouble-sided veneering veneering of offlexible flexible biocomposite biocomposite defines defines a stable a stable curved curved shape. shape. © © BioMat/ITKE—University of Stuttgart. TheBioMat/ITKE internal structure– University of of the Stuttgart. biocomposite fiberboards made of natural fibers and elastomers affectedThe the internal flexibility, structure elasticity, of the and biocomposite structural behavior, fiberboards depending made of naturalon the size fibers of andthe fibers elastomers and The internal structure of the biocomposite fiberboards made of natural fibers and elastomers theaffected mixing the ratio flexibility, with binders elasticity, [17]. and structural behavior, depending on the size of the fibers and the affected the flexibility, elasticity, and structural behavior, depending on the size of the fibers and mixing ratio with binders [17]. 2.1.2.the mixing Form-Finding, ratio with Elements, binders [17].and Connections 2.1.2. Form-Finding, Elements, and Connections 2.1.2.The Form-Finding, parametric Elements,form-finding and Connectionsprocess enabled the possibility to find the final applicable architecturalThe parametric solution, form-findingin which manufacturing process enabled constraints, the possibility , to and find structural the final capabilities applicable werearchitectural Thestrongly parametric solution, interconnected. form-finding in which The manufacturing processprefabricated enabled constraints, components the possibility aesthetics, were to assembled andfind structural the finalin four capabilitiesapplicable large triangularwerearchitectural strongly segments solution, interconnected. on sitein which that The were manufacturing prefabricated then lifted componentsto cons the traints,correct were positionaesthetics, assembled in andspace. instructural fourFour large main capabilities triangular types of modularsegmentswere strongly connection on site interconnected. that details were were then lifteddesignedThe toprefabricated the and correct applied positioncomponents throughout in . werethe Fourwhole assembled main shell types construction, in offour modular large as shownconnectiontriangular in Figure segments details 3. wereTypes on site designed A, thatB, and were and C werethen applied liftedthe throughout ma toin the types correct theof joints wholeposition between shell in space. construction, the Foursegmented main as shown typespanels inof andFiguremodular each3. other, Typesconnection while A, B, details andtype CD werewas the thedesigned main main connectio typesand appl of jointsnied type throughout between that was the responsiblethe segmented whole shell for panelstransferring construction, and each the as loadsother,shown from while in Figure typethe segments D3. wasTypes the A, mainto B, the and connection cross-connected C were typethe ma that inarched wastypes responsible ofwooden joints between forbeams, transferring theand segmented thus the loadsonto panels fromthe foundations.theand segments each other, The to thewhile overall cross-connected type D was the of arched themain shell wooden connectio resembled beams,n type a and 3Dthat thusfabric was onto responsiblein which the foundations. the for curved transferring The elements overall the weregeometryloads connectedfrom of thethe shell bysegments resembledcommon to atheknots 3D cross-connected fabric in all in whichdirections the arched curved in space.wooden elements This beams, were approach connected and thusallowed by onto common thethe biocompositeknotsfoundations. in all directions Thesandwich overall in panel space. geometry elements This of approach the to shell be alloweddismantled resembled the biocompositealater 3D fabricat the in end sandwichwhich of the the panel exhibitioncurved elements elements to be to re-usedbewere dismantled connected in other later designed by at thecommon constellations. end of theknots exhibition in all todirections be re-used in in space. other designedThis approach constellations. allowed the biocomposite sandwich panel elements to be dismantled later at the end of the exhibition to be re-used in other designed constellations.

Figure 3. Isometric view of the four main details composed of single curved panels of the modular system. In combination, the single parts create re-usable structural compositions. © BioMat/ITKE—University of Stuttgart. Buildings 2019, 9, x FOR PEER REVIEW 6 of 13

Figure 3. Isometric view of the four main details composed of single curved panels of the modular system. In combination, the single parts create re-usable structural compositions. © BioMat/ITKE- BuildingsUniversity2019, 9, 64 of Stuttgart. 6 of 13

2.2. Biomimetic Research Pavilion SS 2018 2.2. Biomimetic Research Pavilion SS 2018 The Biomimetic Research Pavilion 2018 was the application of a special interlocking system derivedThe from Biomimetic a biological Research role model Pavilion function 2018 and was the the translation application of ofthose a special principles interlocking into the context system ofderived lightweight from a biologicaland material-saving role model functionarchitecture. and the The translation research of pavilion those principles interlocking into thesystem context was of inspiredlightweight by andDiatoms. material-saving Diatoms architecture.are a type of The alga researche that pavilionusually interlockinglive in water. system Some was types inspired are unicellular,by Diatoms. and Diatoms others are are a able type to of form algae colonies that usually in the live shape in water. of filament Some types ribbons. are unicellular,The aspect that and sparkedothers are the able idea to formof taking colonies this in biological-inspi the shape of filamentred concept ribbons. was The that aspect organisms that sparked lock thevertically, idea of wheretaking thistheir biological-inspired spines act as flaps concept preventing was that organismshorizontal lock displacement. vertically, where Driven their by spines the actbiological as flaps preventinginspiration, horizontal the students displacement. created a unique Driven design, by the biological starting from inspiration, both the the biological students createdrole model a unique and thedesign, choice starting of the frombiomaterial. both the The biological system roleof vert modelical stacking and the and choice interlocking of the biomaterial. uniform components The system wasof vertical translated stacking into a and new interlocking architecture uniform typology, components and by its wasmodular translated building, into the a new consumption architecture of materialstypology, was and reduced. by its modular In the building,pavilion, elastic the consumption deformation of of materials the longitudinal was reduced. designed In the panels pavilion, was activated.elastic deformation In this sense, of the active longitudinal bending designed was applied panels through was activated. bending Inand this interlocking sense, active the bending panels wastogether applied andthrough locking bendingthe endings and in interlocking curved footages, the panels reaching together a final and double-curved locking the endings shell system, in curved as shownfootages, in reachingFigure 4. a final double-curved shell system, as shown in Figure4.

(a) (b)

Figure 4. (a) The erected Biomimetic Pavilion at the ca campusmpus of the University of Stuttgart; ( b) Single pieces with tooth-shaped edges creating a stable interlocking system. ©© A.A. Coban Coban and and V. V. Ivanova; BioMat/ITKE-UniversityBioMat/ITKE—University of ofStuttgart Stuttgart

2.2.1. Material Properties and Customization In order to create thethe double-curveddouble-curved shell structurestructure of the pavilion, 6.5-mm birch wood-based middle-density fiberboard fiberboard (MDF) plates were chosen to be bent and applied as the main structural material. The The MDF MDF was was chosen, because it it offered suff sufficienticient flexibility flexibility and elasticity to achieve the needed curvature.curvature. SinceSince it isit basedis based on wood,on wood, the structure the structure enjoyed enjoyed a high ecologicala high ecological value, especially value, whenespecially the reusabilitywhen the ofreusability the elements of the was elements enhanced was and enhanced applied through and applied the special through developed the special ‘dry developedjoint’ bio-inspired ‘dry joint’ interlocking bio-inspired system. interlocking The elements system. wereThe elements fixed in positionwere fixed inside in position non-anchored inside non-anchoredcurved foundations curved with foundations no screws with to no avoid screws irreversible to avoid shapeirreversible deformation, shape deformation, allowing at allowing the end atthrough the end an through active-bending an active-bending appliance to appliance reach up toto a reach double-curved up to a double-curved interlocked shell interlocked construction. shell construction. 2.2.2. Form-Finding Process 2.2.2.The Form-Finding biomimetic Process inspiration was based on diatoms, which are the micro-algae creatures that are spread in the oceans and enjoy an interesting interlocking structure, as shown in Figure5. Looking The biomimetic inspiration was based on diatoms, which are the micro-algae creatures that are spreadin depth in atthe the oceans detailing and enjoy of the an naturally interesting existing interl interlockingocking structure, structure, as show then architecturein Figure 5. studentsLooking inhere depth have at applied the detailing several of the naturally stages existing to allow interlocking upscaling fromstructure, the microbiological the architecture level students to the heremacroscale have applied architectural several realm. abstraction The applicationstages to allow of this upscaling stacking from and the interlocking microbiological system level was to only the possible by means of applying semi-elastic material plates that were bent and interlocked, which shows how customized materials and biomimetic inspiration were both combined and applied. In this project, bending-active structural conception [18] was applied. Bending-active-based construction is Buildings 2019, 9, x FOR PEER REVIEW 7 of 13 Buildings 2019, 9, x FOR PEER REVIEW 7 of 13 macroscale architectural realm. The application of this stacking and interlocking system was only possiblemacroscale by meansarchitectural of applying realm. semi The -elasticapplication material of this plates stacking that wereand interlockingbent and interlocked, system was which only showspossible how by customizedmeans of applying materials semi and-elastic biomimetic material inspiration plates that were were both bent combined and interlocked, and applied. which In thisBuildingsshows project, 2019how, 9 customized, 64bending-active materials structural and biomimetic conception inspiration [18] was were applied. both combined Bending-active-based and applied.7 of 13In constructionthis project, is usuallybending-active reachable structural when the structuralconception deficiency [18] was or bucklingapplied. of Bending-active-basedsemi-elastic material systemsconstruction are used is usually to enable reachable new typeswhen ofthe structur structuralal systems deficiency and or architectural buckling of semi-elastictypologies thatmaterial are usually reachable when the structural deficiency or buckling of semi-elastic material systems are used reachedsystems depending are used to on enable the bending new types behavior of structur and theal distributed systems and inner architectural stresses within typologies the structural that are to enable new types of structural systems and architectural typologies that are reached depending on elements.reached depending on the bending behavior and the distributed inner stresses within the structural the bending behavior and the distributed inner stresses within the structural elements. elements.In Figure 5, the biological role model is illustrated, and the initial abstraction stages of the In Figure5, the biological role model is illustrated, and the initial abstraction stages of the interlockingIn Figure system 5, the are biological shown. role model is illustrated, and the initial abstraction stages of the interlockinginterlocking systemsystem areare shown. shown.

(a) (b) (c) (a) (b) (c) Figure 5. (a) Paralia sulcata diatom imaged using the University of Tasmania scanning electron microscopeFigureFigure 5.5. (( aa(cc))) ParaliaParalia creative sulcatasulcata commons; diatomdiatom (b) imagedimagedSimplification usingusing theofthe biological UniversityUniversity role ofof model TasmaniaTasmania of stacking scanningscanning system; electronelectron (c) Biologicalmicroscopemicroscope stacking (cc)(cc) creative system commons; translated ( (bb)) Simplification Simplificationinto architectonic of of biological biological approach role role model modelof modular of ofstacking stacking Design system; system; for (c ) Dismantling.(cBiological) Biological stacking stackingb,c: © A. system systemCoban translated andtranslated V. Ivanova; into into architectonic BioM architectonicat/ITKE-University approach approach of modular of Stuttgart.of Designmodular for Dismantling.Design for (bDismantling.,c): © A. Coban b,c: and© A. V. Coban Ivanova; and BioMat/ITKE—University V. Ivanova; BioMat/ITKE-University of Stuttgart. of Stuttgart. 2.2.3. Stacking—A Design for Dismantling 2.2.3.2.2.3. Stacking—AStacking—A DesignDesign forfor DismantlingDismantling The goal of this pavilion was to achieve a well-developed structural system that could be quicklyTheThe goalmounted,goal of of this this paviliondismantled, pavilion was was toand achieve to achievereconstructe a well-developed a welld -developedin different structural structural scales system systemand that couldlocations. that be could quickly The be stacking/interlockingmounted,quickly mounted, dismantled, dismantled,system and reconstructed of theand biological inreconstructe different role scalesd modelin anddifferent resulted locations. scalesin The the stacking/interlocking anddesign locations. of various The homogeneoussystemstacking/interlocking of the biological building system roleelements model of thewith resulted biological tooth-shaped in the designrole edges.model of various Inresulted this homogeneous way, in thean interlockingdesign building of elements variousstable systemwithhomogeneous tooth-shaped was achieved building edges. by elements Insimply this way, pushingwith an interlockingtooth-shaped the individual stable edges. systemparts In together,this was achievedway, which an byinterlocking allowed simply pushingoff-site stable digitalthesystem individual fabrication was achieved parts using together, by computerized simply which pushing allowed numerical off-sitethe individual control digital fabrication(CNC)-assisted parts together, using prefabrication, computerized which allowed numericalfollowed off-site bycontroldigital a quick (CNC)-assistedfabrication on-site assemblyusing prefabrication, computerized process. The followed numerical assembly by acontrol quicktook place on-site(CNC)-assisted in assembly two phases, prefabrication, process. where The at assemblyfollowedfirst the piecestookby a place quickwere in horizontallyon-site two phases, assembly assembled where process. at first on thetheThe piecesground assembly were in a horizontallytook flat format,place in assembledas two shown phases, in on Figure the where ground 6a, at and first in athen flatthe bentformat,pieces and were as held shown horizontally in inshape Figure after assembled6a, andconnecting then on bent the the andground pane heldls’ in inendings a shape flat format, afterto the connecting as curved-shaped shown thein Figure panels’ foundation, 6a, endings and then toas shownthebent curved-shaped and in Figure held in 6b. shape foundation, after connecting as shown in the Figure pane6b.ls’ endings to the curved-shaped foundation, as shown in Figure 6b.

(a) (b) (a) (b) Figure 6. ((aa)) Simple Simple horizontal horizontal stacking stacking by by pushing pushing modules modules into into each each other; other; ( (bb)) Erecting Erecting the pre-mountedFigure 6. (a ) pavilion pavilionSimple by horizontalby manual manual bending, stackingbending, and byandlatter pushing latter fixation fixation modules with with the into curved the each curved foundations. other; foundations. (b) Erecting© A. Coban © A.the Cobanandpre-mounted V. Ivanova;and V. Ivanova;pavilion BioMat/ITKE—University BioMat/Iby manualTKE-University bending, of and Stuttgart. of latter Stuttgart. fixation with the curved foundations. © A. Coban and V. Ivanova; BioMat/ITKE-University of Stuttgart. 2.3. Eco-Pavilion SS 2011 This research pavilion was built in cooperation with 15 companies and academic institutes, as well as 25 architecture students who participated in the (Do It Yourself) educational course under the author’s supervision. The pavilion, which had the dimensions of 4-m length, 1-m width, and 2-m Buildings 2019, 9, x FOR PEER REVIEW 8 of 13

2.3. Eco-Pavilion SS 2011 This research pavilion was built in cooperation with 15 companies and academic institutes, as Buildingswell as 201925 architecture, 9, 64 students who participated in the (Do It Yourself) educational course under8 of 13 the author’s supervision. The pavilion, which had the dimensions of 4-m length, 1-m width, and 2-m height, was first exhibited in the foyer of the main building of the Faculty of Architecture and Urbanheight, Planning was first of exhibited the University in the foyer of Stuttgart, of the main after building which it of was the moved Faculty and of Architecture exhibited separately and Urban in differentPlanning locations of the University and exhibitions. of Stuttgart, after which it was moved and exhibited separately in different locationsThe andproject exhibitions. combined the use of green building materials, which were used not only as structuralThe project elements, combined but also the useas exterior of green and building interior materials, cladding, which flooring, were used and notdecking only assystems. structural It illustratedelements, butan alsoarchitectural as exterior research and interior approach cladding, in which flooring, alternative and decking sustainable systems. building It illustrated solutions an witharchitectural high ecological research approach footprints in whichwere alternativeapplied and sustainable exhibited building to various solutions audiences, with high ecologicalwhether academics,footprints were students, applied or andusers, exhibited as shown to variousin Figure audiences, 7. This approach whether highlighted academics, students,the use of or structural users, as solutions,shown in Figurewhich7 .ensured This approach complete highlighted dismantling the use and of deconstruction structural solutions, for later which reassembly ensured complete and the possibledismantling change and deconstructionof utilization, forusing later special reassembly developed and the dry possible structural change joints of utilization,and a modular using constructionspecial developed system. dry The structural idea of jointsthe Japanese and a modular architect construction Shigeru Ban system.to use recycled The idea cartoon of the Japanesetubes as structuralarchitect Shigeru elements Ban in toarchitecture use recycled has cartoon been tran tubessferred as structural to the Eco-Pavilion elements in 2011, architecture in which has cartoon been tubestransferred were toapplied the Eco-Pavilion as the main 2011, structural in which cartoonelement tubesof the were pavilion applied in as cooperation the main structural with a Stuttgart-locatedelement of the pavilion architectural in cooperation named with a ‘Archite Stuttgart-locatedktur Grosse’. architectural The cartoon office tubes named have ‘Architektur been here appliedGrosse’. as The the cartoon structural tubes background have been to here which applied multiple as the newly structural developed background green building to which materials, multiple whichnewly developedwere designed green buildingand fabricated materials, during which the were educational designed andcourse, fabricated were duringfixed. theAs educationala result, a frameworkcourse, were was fixed. established As a result, that a frameworkdid not only was repres establishedent green that building did not materials only represent as recycled green buildingcartoon tomaterials be applied as recycled as structural cartoon elem toents, be applied but also as structuralprovided the elements, opport butunity also for provided other recycle-based the opportunity and biocomposite-basedfor other recycle-based materials and biocomposite-based to be applied as cladding materials systems. to be applied as cladding systems.

(a) (b)

Figure 7. (a) Interior cladding applications and hanging partitions partitions of of the the Eco-Pavilion Eco-Pavilion (left (left to to right): right): Vacuum thermoformedthermoformed biocomposite biocomposite prototypes, prototypes, hanging hanging partition partition fromwall recycledfrom recycled bottles;plastic (bottles;b) Exterior (b) Exterior cladding cladding application application with free-formwith free-form facade facade panels. panels.© BioMat/ITKE—University © BioMat/ITKE-University of Stuttgart. Photos: Miklautsch.

2.3.1. Material Choices and Structural Usage The pavilionpavilion was was constructed constructed from from recycled recycled cartoon cartoon pipes pipes that were that generated were generated from the from recycling the recyclingof old paper of old from paper the solidfrom wastethe solid stream, waste with stream, a lifespan with a oflifespan around of five around years, five to years, mainly to serve mainly in servetemporary in temporary applications applications and disaster and areas. disaster These areas. pipes formedThese thepipes supporting formed the main supporting structure, whichmain structure,allowed an which additional allowed cladding an additional configuration cladding by configuration other materials. by other Those materials. additional Those materials additional that materialscladded the that structural cladded frameworkthe structural were framework various reinforcedwere various biocomposites reinforced biocomposites that were manufactured that were manufacturedfrom agrofibers, from including agrofibers, cereal including straw short cereal fibers, straw coconut short fibers, fibers, coconut and others. fibers, The and hollow others. section The hollowof the cartoon section pipesof the provided cartoon anpipes excellent provided opportunity an excellent to design opportunity a sustainable to design thermal a sustainable insulation thermalsystem. insulation This was achievedsystem. This by fillingwas achieved the hollow by pipesfilling with the pre-formulatedhollow pipes with recycled pre-formulated fibrillated cellulose. The fibrils were mixed with paper glue and molded within an open mold to suit the application afterwards of these molded geometries between the pavilion’s cartoon pipes for further thermal insulation. Buildings 2019, 9, x FOR PEER REVIEW 9 of 13

recycled fibrillated cellulose. The fibrils were mixed with paper glue and molded within an open mold to suit the application afterwards of these molded geometries between the pavilion’s cartoon Buildings 2019, 9, 64 9 of 13 pipes for further thermal insulation.

2.3.2.2.3.2. Visual Visual Appearance Appearance TheThe research research pavilion’s pavilion’s façadefaçade consistedconsisted of a tiletile system of of individually individually developed developed cladding cladding elementelement prototypes prototypes measuring measuring 30 × 3030 cm,× 30 which cm, werewhich named were TRASHELL named TRASHELL [19]. These biocomposites[19]. These werebiocomposites designed in were free-form designed , in and free-form through style, their and collective through cladding, their collective a desired cladding, 3D physical a desired curvature 3D wasphysical reached. curvature Non-structural was reached. individually Non-structural developed individually green building developed materials, green as building well re-used materials, plastic bottlesas well that re-used were transformed plastic bottles into that threads were and transfor combinedmed ininto the threads form of and panels, combined provided in anthe ornamental form of panels, provided an ornamental cladding system in the form of an interior hanging partition. For cladding system in the form of an interior hanging partition. For the flooring system, recycled paper the flooring system, recycled paper and a small fraction of around 20% glass as well as cement were and a small fraction of around 20% glass as well as cement were applied as aggregates and for binding, applied as aggregates and for binding, respectively, to form new recycled flooring panels. respectively, to form new recycled flooring panels. 2.3.3. Design for Dismantling 2.3.3. Design for Dismantling In order to simplify assembly and disassembly, a connection system was applied that was In order to simplify assembly and disassembly, a connection system was applied that was designed designed from the architecture office ‘Grosse Architektur’, which connected the individual cartoon from the architecture office ‘Grosse Architektur’, which connected the individual cartoon tubes with tubes with digitally prefabricated wooden profiles, as shown in Figure 8. The profiles were placed digitally prefabricated wooden profiles, as shown in Figure8. The profiles were placed into pre-drilled into pre-drilled openings at planned locations of the tubes and then fit at the same size, facilitating openings at planned locations of the tubes and then fit at the same size, facilitating connection and connection and enabling deconstruction in a later stage and re-installation with the same or with enablingdifferent deconstruction . This temporary in a later stage fixed andconnect re-installationion was a dry with connection the same ormethod, with different which did designs. not Thisrequire temporary adhesives fixed to connectionfit. was a dry connection method, which did not require adhesives to fit.

(a) (b) (c)

FigureFigure 8. 8. ((aa)) Fixation of of cartoon cartoon tubes tubes and and drilling drilling holes holes for further for further assembling; assembling; (b) Pre-drilled (b) Pre-drilled holes holesin desired in desired location location for forassembling assembling with with dry-connection dry-connection bolts; bolts; (c) ( c)Interlocking Interlocking dry-connection dry-connection woodenwooden bolts bolts ensuring ensuring assemblingassembling and dismantling dismantling of of the the pavilions’ pavilions’ structure. structure. (Photos: (Photos: H. Dahy) H. Dahy) © © BioMat/ITKE—UniversityBioMat/ITKE-University of Stuttgart of Stuttgart

3.3. Results Results InIn all all three three case case studies studies carried carried out out between between 2011–2018, 2011–2018, the philosophythe philosophy of ‘Materials of ‘Materials as a Designas a Tool’Design was Tool’ applied, was where applied, green where building green materialsbuilding ma wereterials given were a priority given a to priority be setas to the be mainset as driver the behindmain driver the whole behind design the processwhole design until theprocess construction until the phase.construction The basic phase. idea, The which basic characterizedidea, which thecharacterized three pavilions, the three was pavilions, to design was modular, to design reusable modular, closed reusable material closed systems, material based systems, on abased strong examinationon a strong of examination the building materialof the building as an initial material stage as in thean designinitial stage process. in Thethe designsdesign process. of the research The pavilionsdesigns alwaysof the focusedresearch inpavilions detail on always their own focuse specificd in architecturaldetail on their challenges own specific and illustrated architectural their implementationchallenges and throughillustrated the their use andimplementation purposeful modificationthrough the use of different and purposeful green building modification materials, of suchdifferent as wooden-based green building fiberboards, materials, recycled such as cartoonwooden pipes,-based orfiberboards, biocomposites. recycled cartoon pipes, or biocomposites. The most recently constructed BioMat Research Pavilion 2018, which was exhibited on the campus The most recently constructed BioMat Research Pavilion 2018, which was exhibited on the of the University of Stuttgart, focused on finding innovative solutions for modifying a flexible, elastic campus of the University of Stuttgart, focused on finding innovative solutions for modifying a biocomposite material in a way that allowed it to perform structural functions, as well as create a flexible, elastic biocomposite material in a way that allowed it to perform structural functions, as unique aesthetic configuration. The selection and analysis of the materials in the design process well as create a unique aesthetic configuration. The selection and analysis of the materials in the determined not only the global geometry of the pavilion, but also the order, size, and shape of the individual elements of the modular building systems. The Biomimetic Research Pavilion 2018 depended on the analysis of an interesting stacking/interlocking feature of a biological role model. With the help of the abstracted designs, it was possible to develop an assembly/dismantling method to allow full control over the end-of-life Buildings 2019, 9, 64 10 of 13 scenarios. The elastic yet self-supporting material properties were also settled in the initial design phase, and for this, wood-based MDF panels were the settled applied materials for this project. Through in-depth analysis, the biological-inspired structures were actively bent and locked in the desired positions to transform the settled integrated concepts into an architectural realm. By this bio-inspired interlocking tooth-like design of individual building elements, a quick dismantling and reassembling was guaranteed. Accordingly, the shell-shaped structure offered the possibility of performing a wide variety of tasks, and could be mounted in different locations. The third research pavilion, the Eco-Pavilion 2011, was primarily an of the DfD approach combining different green building materials and establishing sustainable building systems. Unlike the other two pavilions, the fundamental idea of the structural framework and the material composition was not re-developed. Here, recycled cartoon pipes were modified by carving slots for the wooden joints, which acted as ‘dry’ structural connections. This recycled and recyclable structure was applied as a background to other biocomposite products, recycled cladding products, and flooring products. The three research pavilions represent not only the use of green building materials in architectural applications, but also the results of multidisciplinary work. In these projects, architects were not only pure designers, since the close cooperation with external experts naturally expanded the field of the architects’ work. The knowledge gained from material researchers led to functional adaptations of the building materials. The circular design exchange with civil engineers, fabrication technicians, and other external specialists regularly showed the capabilities of introducing the material in the design process, allowing an expression of a new philosophy in design-thinking, based on setting ‘Materials as a Design Tool’. This led to a high level of design and solutions in modular building systems. By constantly adapting to functional demands, the individual components developed their own aesthetics. In the following, Table1, an analytical comparison of the three case studies is illustrated.

Table 1. Analytical comparison between the three case studies, regarding design, applied materials, DfD, and design freedom. CNC: computerized numerical control.

Case Study 1 Case Study 2 Case Study 3 Comparison Criteria BioMat Pavilion Biomimetic Pavilion Eco-Pavilion Customizing flexible The interlocking system was High ecological footprint by biocomposite panels into elements inspired by a biological role combining green building with structural capabilities, model. Semi-flexible Strategy materials with innovative dry creating new architectural and materials were applied to reach connection system. Modular aesthetic expressions for through active-bending new shell system applications. . design formations. Recycled cartoon tubes; wood; Elastic wood-based fiberboards; Sustainable Building cellulose fibers; various elastic biocomposite fiberboards; Elastic wood-based fiberboards Materials Applied biocomposites; recycled 3D Veneer and paper Drilling for the dry joints’ slots, robotic drilling for Digital Fabrication CNC-assisted prefabrication, molds’ fabrication of CNC-assisted prefabrication Applied vacuum-assisted lamination cladding system, laser cutting in post-processing of interior cladding system Design for Yes Yes Yes Deconstruction (DfD) Elements are interlocked vertically, Single-curved elements combined bending in one direction, and then in space in six directions, creating Pre-drilled grid of ‘dry joints’ locked in a curved non-anchored Design Freedom a double-curved segmented shell allow the horizontal or vertical foundation, leading to a construction with new innovative arrangement of tubes. double-curved shell spaces and aesthetic expressions. system formation. Buildings 2019, 9, 64 11 of 13

4. Conclusions The innovative application of newly developed green building materials and their digital fabrication possibilities were the main drivers in the design thinking process, introducing new perspectives of design and establishing new design philosophies. The strong involvement of the choice and characteristics of the materials from the beginning of the design process establishes new ways to develop ideas, which helps solve architectural problems in a much more sustainable way. Through in-depth knowledge of the properties of these building materials and the ability of further customizing them to reach up to advanced properties and controllable end-of-life scenarios, more sustainable building concepts were developed. The possibility of the individual composition of these green building materials ensured a controlled and directed closed life cycle, which was defined by recyclability, compostability, re-usability, and a holistic improvement of the ecological footprint. Since the newly developed biocomposite fiberboards were, unlike wood, not bound to a predefined fiber configuration, the same base material enjoyed the ability to function as an insulating, structural, or purely aesthetic building component, according to changes in its internal recipe and by combining it externally with reinforcing elements. That happened especially in the first case study. In order to ensure further future sustainable solutions within architectural designs and guarantee their implementations, it is important to develop and apply modular building systems that can be assembled and dismantled to allow proper material savings. This will allow the possibility of applying the same building system in different applications. The use of biocomposites and biomaterials with their ability to be adapted and customized to various structural capabilities is a suitable solution for a wide range of new developed architectural applications, which is hereby in many ways proved. The limitations of this suggested design philosophy’s usage of setting ‘Materials as a Design Tool’ depend on the depth of the architects’ interdisciplinary work and the level of their interest in technicalities and other related disciplines to architecture, such as material developments and fabrication techniques. That is why the development of an architectural design process that manifests itself through the choice of materials, structure, aesthetics, and above all, , was only made possible by a stronger linking of different fields of studies, such as the areas of natural , construction, material scientists, and fabrication experts, and their exchange of experiences. The multidisciplinary exchange allowed the development of more sustainable and intelligent solutions for architectural challenges, since not only a linear exchange of knowledge took place through materials research, but between the architects and experts of diverse disciplines was also established. Adopting ‘Materials as a Design Tool’ as a design philosophy is hereby initiated from the author, and highlighted through different developments in the form of pavilions and prototypes to spread the word in the architecture community, so as to help initiate this field of design-thinking and philosophy toward more sustainability in the near future of architecture.

Funding: The first case study, BioMat pavilion 2018 was funded by Agency for Renewable Resources (German: Fachagentur Nachwachsende Rohstoffe e.V. or FNR) under the Ministry of Food and Agriculture (BMEL) in the framework of the Research Project (BioProfile) funding number FKZ: 22021516. The same case study was also partly funded from the Baden-Württemberg Stiftung and the University of Stuttgart. Acknowledgments: The author would like to thank all of the participants in the development and erection of the BioMat pavilion 2018, including around 40 architecture students over two semesters (WS 17/18 and SS 18) who attended the educational academic course (Flexible Forms Pavilion) and in cooperation with BioMat employees Jan Petrs, Michaela Mey and Piotr Baszynski under the author’s supervision. The author would also like to thank the BioProfile project partners including: Fraunhofer-Institut für Holzforschung (Fraunhofer WKI), Mathias Stange ETS, Naftex GmbH and Profine GmbH. BioMat pavilion consultants included: Technical University Eindhoven in the Netherlands (TU/e)-Department of -Patrick Teuffel, Arjan Habraken and Derk Bos as well as Urlike Kuhlmann and Janusch Töpler from the Institute of Construction and Structural Design (KE, Faculty 02: Civil and Environmental Engineering) and Volker Schwieger as well as Gabriel Kerekes from the Institute of Engineering Geodesy (IIGS, Faculty 06: Aerospace Engineering and Geodesy), University of Stuttgart. In addition, the author thanks the students: Arzun Coban and Viktorya Ivanova for designing and fabricating case study 2: The biomimetic pavilion under the author supervision. Also, the author thanks the 25 architectural students who participated in the educational course (Do It Yourself) in the academic semester SS11, which was also at the faculty Buildings 2019, 9, 64 12 of 13 of Architecture and Urban Planning of the University of Stuttgart, and participated in designing and fabricating the third case study, the Eco-Pavilion, including the students: Susanne Hügel, Lousia Scherer, and Kerstin Meyer, who designed and fabricated the TRAshell product under the author’s supervision. The author also thanks all of the partners, companies, and institutes who supported the erection of the third case study, including: Werner Grosse from the Architektur Grosse architecture office in Stuttgart, who designed the structural components of the ‘Eco-Pavilion’ as well as the companies Kartonagen Müller GmbH and Hoffmann GmbH, for their partial support with the structural cartoon pipes materials and the wooden profiles, respectively. Conflicts of Interest: The author declares no conflict of interest.

References

1. Plattner, H.; Meinel, C.; Leifer, L.J. Design Thinking. Understand—Improve—Apply; Plattner, H., Meinel, C., Leifer, L., Eds.; Springer: Heidelberg, Germany; London, UK, 2011. 2. Crowther, P. Design for Disassembly—Themes and Principles; The Royal Australian Institute of Architects, 2005. Available online: https://eprints.qut.edu.au/2888/1/Crowther-RAIA-2005.PDF (accessed on 13 March 2019). 3. Scheelhaase, T. Zukunft: Klimaschutz Kompostierung; Environmental Protection Encouragement Agency, EPEA Internationale Umweltforschung GmbH: Hamburg, Germany, 2009. 4. Eurostat Statistics. Available online: https://ec.europa.eu/eurostat/statistics-explained/images/a/a0/ Waste_generation_by_economic_activities_and_households%2C_2014-1.png (accessed on 19 February 2019). 5. United Nations Environment Programme. Global Status Report 2017. Available online: https: //www.worldgbc.org/sites/default/files/UNEP%20188_GABC_en%20%28web%29.pdf (accessed on 19 February 2019). 6. United Nations. Resilient People, Resilient Planet. A Future Worth Choosing, the Report of the United Nations Secretary-General’s High Level Panel on Global Sustainability; United Nations: New York, NY, USA, 2012. 7. Herczeg, M.; McKinnon, D.; Milios, L.; Bakas, I.; Klaassens, E.; Svatikova, K.; Widerberg, O. Resource Efficiency in the Building Sector. Final Report; Ecorys, DG Environment: Rotterdam, The Netherlands, 2014. 8. Lepelaar, M.; Hoogendoorn, A.; Blok, R.; Teuffel, P. Bio-based composite pedestrian bridge. In Proceedings of the IASS Annual Symposium 2016 “Spatial Structures in the 21st Century”, Tokyo, , 26–30 September; pp. 1–10. 9. Kibert, C.J. Sustainable Construction: Green and Delivery, 4th ed.; John Wiley & Sons, Inc.: Hoboken, NJ, USA, 2016. 10. Guy, B.; Ciarimboli, N. DfD. Design for Disassembly in the Built Environment. A Guide to Closed-Loop Design and Building; Hendrickson, K., Ed.; Hamer Center for Community Design, The Pennsylvania University: Old Main, PA, USA, 2008. 11. Dahy, H.; Knippers, J. Flexible High-Density Fiberboard and Method for Manufacturing the Same. European Patent EP3166765A1, 13 January 2016. Based on Same Patent, Also Applied as WO2016005026A1; CN106604806A; US20170144327, EP2965882 A1. 12. Ellen Mac Arthur Foundation. Growth within. A Circular Economy Vision for a Competitive Europe; McKinsey Center for Business and Environment, Ellen MacArthur Foundation Publishing: Cowes. Available online: https://www.ellenmacarthurfoundation.org/assets/downloads/publications/ EllenMacArthurFoundation_Growth-Within_July15.pdf (accessed on 19 February 2019). 13. Dahy, H. FLEXIBLE FORMS: Experimentieren von Biobasierten Materialien für eine Zukünftige Nachhaltige Leichtbau-Architektur. Available online: https://www.architekturblatt.de/flexible-forms-experimentieren- von-biobasierten-materialien-fuer-eine-zukuenftige-nachhaltige-leichtbau-architektur/ (accessed on 19 February 2019). 14. Dahy, H. Efficient Fabrication of Sustainable Building Products from Annually Generated Non-Wood Cellulosic Fibres and Bioplastics with Improved Flammability Resistance. Waste Biomass Valorization; Springer: /Heidelberg, Germany, 2017; pp. 1–9. [CrossRef] 15. Dahy, H. Natural Fibre-Reinforced Polymer Composites (NFRP) Fabricated from Lignocellulosic Fibres for Future Sustainable Architectural Applications, Case Studies: Segmented-Shell Construction. Acoust. Panels Furnit. Sens. 2019, 19, 738. [CrossRef][PubMed] 16. Dahy, H. Biocomposite materials based on annual natural fibres and biopolymers—Design, fabrication and customized applications in architecture. Constr. Build. Mater. 2017, 147, 212–220. [CrossRef] Buildings 2019, 9, 64 13 of 13

17. Dahy, H. Agro-Fibres Biocomposites’ Applications and Design Potentials in Contemporary Architecture: Case Study: Rice Straw Biocomposites; University of Stuttgart: Stuttgart, Germany, 2015. 18. Lienhard, J. Bending-Active Structures: Form-Finding Strategies Using Elastic Deformation in Static and Kinetic Systems and the Structural Potentials Therein; University of Stuttgart: Stuttgart, Germany, 2014. 19. TRAshell Building Element. Available online: https://www.raumprobe.de/material/universitaet-stuttgart- itke-institut-fuer-tragkonstruktionen-und-konstruktives-entwerfen/trashell/datenblatt/ (accessed on 19 February 2019).

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