The Tectonic Potential of Design for Deconstruction (DfD)

Søren Nielsen, Olga Popovic Larsen The Royal Danish Academy of Fine Arts, Institute of Technology, Copenhagen Denmark

Abstract

Along with the implementation of high standards for energy saving in new buildings further resource conserving action must focus on strategies for prolonging the lifetime of buildings, their parts, components and materials. Spatial and technical strategies must be deployed to increase buildings' capacity for transformation according to change. Design for Deconstruction (DfD) is a technical strategy enabling changes in building configuration without generating waste. DfD has primarily been described as a technical matter, e.g. reversible connections and layering. However, the architectural potential is considerable, and actualises the concept of 'tectonics'; architectural expression by means of construction. By systematically investigating the relationship between technical guidelines of DfD and tectonic articulation, resource conserving necessity may turn into an attractive inspirational source for architects. Through a number of case studies, relations are mapped and tectonic potentials are registered. Hereby, the architectural potential can be detected, documented and categorised as tectonic motifs.

Keywords: Resource conservation, Design for Deconstruction (DfD), tectonics, assembly diagram, motif

1.0 RESEARCH AIM AND CONTEXT On the background of a future agenda of conserving resources, architectural design practice is facing a shift in its technical paradigm: From designing for permanence to designing for constructive reversibility. This change will stimulate the technical core competencies of the architectural profession, actualising the concept of tectonics; artistic expression by means of construction. The study described in the following attempts to point out ways to describe the connection between Design for Deconstruction (DfD) and architectural design strategies. The motif generating potential of DfD is demonstrated through technical and tectonic analysis of case examples.

1.1 The resource agenda Today in most European countries, the lowest hanging fruits of energy saving have been reaped by saving energy for building operation. To reach further goals, lifetime processes and embodied energy must be addressed as a design parameter. Though 50% of demolishing waste is recycled, little is prepared for reuse and large amounts of resources are lost.

The reuse ratio could potentially be raised drastically and huge amounts of resources could be saved if buildings and components were designed for deconstruction. Technical guidelines must be taken into operation by building designers but the potential is far from only technical as cultural value to buildings might be added simultaneously. While resources can be assessed by life-cycle assessment (LCA), the cultural assets of building identity cannot be calculated quantitatively, and yet identity has the capacity to become the most critical factor of

longevity, as buildings that lose their cultural status are more likely to be demolished.

1.2 Solution strategies DfD, as technical solution and as architectural strategy, must be seen in relation to the three main strategies for resource preserving:

Longevity of buildings: Minimizing resource consumption for building interventions e.g. replacements, conversions, additions and maintenance. This can be obtained by adaptability, e.g. versatility, convertibility and scalability [1], by means of robust spatial composition: large free spans, generous ceiling height and surplus structural capacity.

Longevity of components: Avoiding waste generating and downcycling by technical strategies, e.g. refitability, movability and adjustability by designing for deconstruction (DfD). DfD covers a wide range of guidelines and recommendations. Based on previous research [ 2 ] a short set of technical design rules of particular relevance to architectural design, comprises: 1. Reversible fixations, enabling deconstruction without

damage of materials. This implies in general mechanical assembly rather than chemical (cast, glued).

2. Hierarchical assembly according to component lifetime, enabling interventions with a minimum of interference in components with longer lifetime.

3. Accessibility of fixations, enabling deconstruction without damaging components.

4. Parallel assembly, enabling local exchange of single components.

5. Handleable size and weight of components, enabling changes and deconstruction without crane-lifts.

6. High generality (modularity, homogeneousness and uniformity) increases the reusability of components.

7. Minimum of mechanical degradation, e.g. cutting, carving and penetration, minimises waste and increases the reusability of components.

8. Orthogonal geometries (rather than skewed or curved) minimises waste and increases the reusability of components.

9. Minimal number of component types eases as well the deconstruction as the salvaging process.

Cultural value: longevity can be pursued through cultural value by achievement of a protecting 'lovability' [3]. As only a minority of buildings will achieve protection or even conservation, DfD constitutes a 'safety net strategy' by ensuring the possible salvaging of building materials for reuse at end of life. By cultivating DfD to increase cultural value, e.g. by exquisite detailing, a double, strategic 'safety net' can be held under the building resources.

2.0 TECTONICS How can DfD be deployed in order to increase buildings' cultural value? Constructive reversibility, as the primary command of DfD, highlights the significance of bringing construction technology into the very centre of architectural design. In this respect, the notion of tectonics might be a key to evoke a new resource saving building culture.

Tectonics can be defined as 'a certain expressivity arising from the statical resistance of constructional form' [4] and correspondingly: 'the atectonic: visually neglecting or obscuring the expressive interaction of load and support'. The following cases represents an approach to link tectonics with DfD in a systematic way by demonstrating how DfD is simultaneously an engineering discipline and an architectural strategy: Architectural motifs are generated from hierarchical assembly according to lifetime layers and from features of mechanical assembly enabling such as bolts, brackets, screws or springs.

3.0 METHODOLOGY This study is based on investigation and analysis of four case studies chosen among housing schemes, the functional category constituting 75% of the total built area: Two high-profiled demonstration projects, and two ordinary low-cost residences displaying deconstruction as an inherent part of industrialised construction systems. The cases below are all designed to meet contemporary regulatory standards for building insulation.

3.1 Analytic tools Cases are analysed in parallel: Technically, by assembly diagrams, and narratively, by denotation of the tectonic principles behind the architectural motifs. Assembly diagrams

The assembly-diagram translates actual technical solutions into visualisations of component placement in a layered structure. By analysing the assembly structure, the actual capacity for deconstruction is documented by ensuring that disassembly can take place without interference in more permanent neighbouring layers. From the assembly diagram it is possible to map the

logistic and technical functionalities that conditions the tectonic motifs. Detail drawings Narratives attached to the technical solution unfold in the scale of the detail [5], making the 1:5 drawing the primary study object, fig. 1. On the technical level, constructions are described according to the functionality of the component, and the delineation between DfD and non-DfD parts are marked and similarly are marked a boundary between off-site and on-site construction.

Figure 1: Principle diagram; parallel study of technical principles and tectonic motifs.

On the tectonic level, constructions are described as actions of designing, such as 'hanging', 'clamping', 'penetrating', etc., and denoted by pictograms. These actions represent architectural motifs attached to the assembly technique. By identifying basic form principles from actual designs, an 'alphabet' of tectonic categories can be developed.

3.2 Case presentation Case 1: Bolig+ by Vandkunsten 2009 is a scheme for an open building system with energy consumption below zero obtained by means of passivehaus technology and integrated renewable energy sources. Spatial versatility and reversible assembly technique are employed as long-term resource-saving strategy.

In order to separate the more volatile skin layer from the permanent structural layer (prefab concrete elements), non thermal-conducting intermediary consoles of fibreglass are attached to the slab edges, resulting in a gargoyle-like motif, fig. 2, onto which additional applications can be mounted such as balcony element, sunscreens or windshields.

Figure 2: Vandkunsten Bolig+: consoles for connecting climate shield and applications to structural layer. The separate structure and skin layers are visibly displayed in the interior, fig. 4, as a double framing motif enforced by different materials: concrete and wood. In this, the motif appears as a combination of two layers. The console element exemplifies how mechanical connections can be designed as autonomous components rendering an architectural motif, figs. 2-6.

Figure: 3: Vandkunsten Bolig+, assembly diagram.

Figure 4: Vandkunsten Bolig+, proposal for zero-energy residences 2009, interior with exposed layering of facade elements.

Figure 5: Vandkunsten Bolig+, proposal for zero-energy residences 2009, section of façade. Case 2: Kvistgård by Vandkunsten is a scheme for low-dense, low-cost residences built with prefabricated panel-elements. The buildings are assembled in a way that enables reversible action. By turning the cladding board from vertical (pre-mounted) to horizontal (mounted onsite) the assembly connections between panels are manipulated into a characteristic motif of two layers of boxes sliding on top of each other, figs. 7-8. As the stud-frame structure is atectonically hidden by cladding on both sides, all visible motifs appear in the skin layer, fig 9.

Figure 6: Vandkunsten Bolig+, façade detail.

Figure 7: Vandkunsten 2007 Kvistgård. Photo by Adam Mørk.

Figure 8: Vandkunsten Kvistgård, low-dense terraced housing 2007.

Figure 9: Vandkunsten 2007 Kvistgård, façade detail.

Figure 10: Vandkunsten 2007, Kvistgård, assembly diagram. Structural members and the complete skin layer are integrated in prefab panel elements except for the on-site façade cladding covering the connections.

Case 3: Almen+ by Vandkunsten is a scheme for low-cost terraced housing based on prefab volumetric elements with stud-frame structure and cladding of hard, fibre-reinforced gypsum.

While connections between volumes are hidden, the secondary construction for the façade cladding comes to define the dominant exterior motif, figs. 11-14: Pitched boards, reflecting the on-site mounting process where boards are placed in position from a lift. By using stock-measured board modules and frictional fixation screws, instead of drilled penetrations the cladding construction is designed for disassembly. Rhythmically placed steel hooks generate a characteristic motif.

Figure 11: Vandkunsten, Almen+, section of façade module.

Figure 12: Vandkunsten 2009, Almen+, block typology.

Figure 13: Vandkunsten 2009, Almen+, assembly diagram.

Figure 14: Vandkunsten 2009, Almen+, façade detail.

Case 4: The Loblolly house is a single-family holiday residence designed for a maximum degree of prefabrication. The structure is a patented scaffolding system of extruded aluminium profiles assembled with steel connections forming a 3D framework in which wooden stud-frame volumes are inserted.

In Loblolly House a series of motives are displayed in parallel, each one of them connected with the respective constructive layer: The structure designed by the

Figure 15: KieranTimberlake, Loblolly House, assembly diagram. The construction performs a full DfD-design as even the foundation can be dismantled.

Figure 16: KieranTimberlake, Loblolly House 2008, exterior. Photo by Ulrik Stylsvig.

manufacturer (Bosch) becomes an adopted motif, whereas the fragmented sections of pre-fabricated wooden façade cladding stand out as an original, individually designed motif. In terms of layering, the wooden boards constitute a mere surface function of the skin layer, locating the buildings' exterior identity in the most volatile part of the assembly hierarchy.

4.0 INTERPRETING DFD-RELATED MOTIFS From the cases analysed above, that exemplifies how reversible assembly and tectonic motifs correlate, a number of phenomena can be found.

In all cases it is the structure and skin layers that are subject to articulation efforts, whereas service, space plan layers appear atectonic due to hidden connections. In other buildings motifs might be found emerged from those layers.

Figure 17: KieranTimberlake, Loblolly House, facade detail.

The motifs found in the four cases are related to the DfD-principles as displayed in the matrix below, fig. 18. From the matrix a number of characteristic features can be found: 1. Unexploited potential: The matrix makes it visible to what degree the DfD guidelines has not been a vehicle for architectural expression.

2. All DfD guidelines are potentially motif-generating: Motifs are found with all categories of guidelines.

3. Mechanical, connections are most rich in motifs: Mechanical, accessible connections, typically found with steel and aluminium joints, produce significant motifs often with ornamental and decorative qualities.

4. Super-motifs: Some motifs are found to relate simultaneously to a multiplicity of guidelines, e.g. the sliding motif in Kvistgård and the frame-structure of Loblolly.

5. DfD-related motifs are found along with non-DfD-related motifs: Even when DfD principles are followed consequently motifs emerge with no reference to DfD. At the level of volumetric composition motifs are found which are not specific to DfD though produced by DfD assembly methods.

6. Scale: Tectonic articulation, by means of reversible assembly details, materialises at different levels of scale. Assembly details can generate motifs in macro-scale. In the Kvistgård case the displacement of volumes is narrated as an event of sliding on the ‘rail’ of the horizontal cladding. Loblolly’s scaffolding grid attains a three dimension plug-in motif at the volumetric scale. Motifs such as stacking, sliding, segmenting or cantilevering are found to be scale independent.

7. Lifetime layers Constructive layering in itself can produce significant motifs at multiple scale levels as found in the frame-and-filling motif of Loblolly and the double frame motif of Bolig+.

Figure 18: Matrix showing tectonic motifs' relation to DfD guidelines.

In insulated constructions the most identity constituting elements can be found as highly peripheral parts of the structural hierarchy, which confirms that the narratives of modern architecture unfold at the surface level as a consequence of technical independency between façade and structure [6]. Within a DfD regiment buildings become 'paper-dolls' allowing the exterior identity to be easily changed by tacking façade element to intermediate structures. This strengthens the buildings' robustness but challenges authorship by assigning influence to users and second-generation designers.

5.0 CONCLUSION The DfD building technique is capable of being integrated in architectural design as a resource of motifs that can be used for adding individual identity to buildings. The relationship between technical guidelines and motifs can be decoded as attempted above and revealing a multiplicity of architectural expressions is revealed.

5.1 Architectural potential

Architects may on the one hand dismiss tectonic opportunities in DfD in the structural layer when members are integrated due to insulation thickness, but numerous motifs can be created within and between the more

volatile layers. This implies an increased focus on buildings' details, including assembly logistics that are, however, somehow peripheral disciplines in much architectural design practice. Bringing the methods of DfD into the core repertoire of design practice might change this picture and result in long-term resource savings. Though the commitment to technical reversibility imposes some new restrictive conditions to the design framework, new means for expression occur from finding constructive solutions to the challenge.

5.2 Perspectives By incorporating DfD in the repertoire of architectural profession as a means of expression, the development towards a resource-gentle building practice can be pushed forward. While there is a developed body of knowledge on the technical aspects of DfD, the architectural potentials of DfD are still relatively unexplored, partly due to the lack of empiricism. Further research in e.g. the potential of specific materials, technical functionality or architectural themes can expand the field. The architecture of DfD might eventually have a cultural perspective: DfD may change the ways buildings are conceived into a more dynamic direction, since DfD technically allows an increased influence from users and other_stakeholders.

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[3] Eberle, J. in: Nerdinger, W. (ed) 2007: Baumschlager+Eberle, Recent Projects 2002-2007 Architecture, People and Resources, Wien, Springer

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[5] Frascari, M. 1984: The tell the tale detail – in Via7, University of Pensylvannia p. 23-37

[6] Leatherbarrow, D. and Mostafavi, M. 2002: Surface Architecture, The MIT Press, Cambridge Massachusetts