A much more familiar process of developing two-dimensional surfaces into three-dimensional forms is that of folding. In addition to articulating flat sheet materials into formal propositions, folding has rich potential for defining structural geometry. Through folding, the self-supporting effective span and rigidity of sheet materials may increase substantially, offering further design developments. In comparison to contouring, folding is very economical in material terms. Already an engaging method of exploring design ideas at various scales, digital fabrication has afforded even further experimentation with this material operation. Perhaps the most immediate characteristic of folding is the continuity of space, surface and form it provides, enabling a fluidity distinct from most other tooling methods. It is possible to understand folding not simply as a representational approach offering direct, dynamic – i.e. continuous – relationships between design elements, but also as a generative technique that, through exploration of a surface’s features and how these may be further nuanced, may prove valuable to the designer. Whilst the material operation may seem relatively finite when using traditional methods, digital technologies enable the calculation and setting out of complex fold patterns, furnishing the practitioner with a greater spectrum of design options. As a translation process, converting two-dimensional surface into three-dimensional modulated form, folding already has an extensive history in product design and other creative disciplines. However, digital-fabrication technology readily allows the designer to shift from a scale model to full-size spatial prototypes and installations, which permit the architectural qualities of design ideas to be not only explored but also directly experienced.
The apparently limitless potential of folding as a tooling strategy has, as with all the other approaches described in this section, been assisted by digital design software, including a number of programs with specific functions within their interfaces that convert free-form surfaces into unfolded pattern sheets ready for digital fabrication. The data for these unfolded sheets is usually used with cutting machines – particularly laser cutters, although plasma and water-jet cutters may also be engaged for this process. The advantage of laser cutters is that they can score sheet material rather than cut all the way through its thickness, affording folds to be more easily made, whereas other cutters create a series of holes – typically lines of perforations – to assist folding. In material terms, the very act of manipulating the surface through bends, creases and other modulations requires that the intended sheet be flexible in nature, and as a consequence thick paper, sheet metal and plastics are the most commonly used materials – although the latter necessitates heating to become suitably pliable.
Folding is often an integral feature of many contemporary architectural designs, aided by the ability of computation to fold and unfold designs and analyze different variables. For the China Central Television (CCTV) Headquarters by OMA, two towers lean towards one another and connect in an apparently gravity-defying cantilever (left). The distinctive loop was developed through
extensive analysis of structural implications alongside aesthetic considerations, and necessitated digital simulation of the building façade’s bracing structure as a composite, unfolded skin (right).
The strategy of folding is clearly evident in the articulated exterior of UNStudio’s design for the Theatre Agora, Lelystad, which follows the flat, unfolded patterns of the diagrammatic elevations to create a three-dimensional sculptural form. The building’s envelope comprises an overlapping multifaceted surface, whose perforations create a kaleidoscopic effect.
The logic of folded surfaces continues throughout, and is amplified in the auditorium where it provides both a formal and acoustic strategy.
Case study Folding as surface strategy
Reiser + Umemoto – Vector Wall, New York, 2008.
The Vector Wall imagines ways that a simple laser cutter can perforate a flexible or semiflexible material with multidirectional patterning, reinterpreting the common wall. The project explores the system of laser cutting a standard steel sheet and bending/folding it to create an undulating perforated surface; once cut, a flat steel sheet can form a volumetric, scalable, diaphanous scrim. This flexible wall module can extend from its original 1.2m x 2.4m sheet size into a dimensionally variable panel. Through this approach to laser cutting, a standard material may transcend its dimensions not only in the X and Y axes but also in the Z axis, exponentially increasing the variety of its uses.
Vector Wall illustrates late twentieth-century prefabrication logic taking advantage of new digital design and manufacturing processes. The idea of developing a rigid plane into an independent articulated surface arrived relatively early in the design process. It developed from an interest in rigid fabric systems as building materials, and migrated towards steel as an efficient medium, exhibiting strength and rigidity while remaining extremely thin. The final size of the piece is a direct result of the prefabrication dimensions of standard steel sheets, as the designers attempted to utilize as much of each sheet as possible. In its final iteration, the design was split into six pieces to conform to cutting beds, transportation and finishing constraints. The pieces were cut, fabricated, individually powder-coated and then bolted together with removable fittings to allow easy transportation, installation and disassembly.
A The design process explored laser-cutting a rigid sheet by prototyping in paper. This enabled a study of volumetric and surface effects, while partially understanding the limited flexibility of the system.
B Once a method for manipulating the surface was established, prototyping in steel was essential in evaluating the effects and failures of the forms responding to the cut pattern in the actual material. The designers worked closely with the laser cutter to determine the thickness and composition of the material, as well as minimum and maximum cut widths, cut lengths and spacing. As such, the entire process of designing included as much, if not more, making and testing as it did planning.
C Essential to the design was the isolation of formal variables in the cut pattern, and the various effects they produced on the resultant surface. The final form combines structural articulation – such as branching, weight distribution and material accumulation – with aesthetic or atmospheric effects, such as variable visibility, porosity/opacity, luminosity and perceived spatial manipulation and material flow.
The Starlight Theatre, Rockford, by Studio Gang Architects, incorporates a faceted roof structure whose folding geometry permits the centre sections to open upward, so that each roof panel overlaps its neighbour in a similar manner to flower petals. Replacing an existing outdoor venue, the central theatre space forms an unexpected vertical axis, an observatory to the stars through a kinetic steel-and-timber roof that opens in fair weather.
Case study Folding as reconfigurable and interactive installation
sixteen*(makers) – Blusher, various locations, 2001.
A CAD drawing indicating four of the variably cut steel plates with fold lines demarcated.
B This information then informed the CNC plasma-cutting process.
C The cut components were pressed to achieve the folds, and fabricate three-dimensional pieces from two-dimensional shapes of material.
D The network of sensors, which detect proximity and movement near the installation, were connected to the folded elements.
This practice’s interdisciplinary research is primarily developed through the practice of making, with respect to the impact of digital technologies and time-based architecture. Their projects explore the interfaces between craft and manufacturing, utilizing a variety of techniques including CAD/CAM processes and software script writing. Conceived as an adaptive and variable installation, to be set within a number of exhibition spaces, Blusher negotiates spatial and temporal relationships between occupants and their environment.
Blusher is effectively a kit of interchangeable elements, allowing assembly at each venue with specific spatial relationships to the site. It comprises three series of components: firstly, a set of 21 variably cut and folded steel plates, capable of interconnecting in several ways; secondly, a network of embedded sensors including proximity sensors, retro-reflective beam breakers and a sonar device; and thirdly, a layered surface of polycarbonate leaves with responsive properties, known as ‘feathers’.
E AND F The differential qualities of logged data, once correlated and assessed, allowed fine-grain inferences to be made about movement, direction, density, proximity and occupancy-duration. Subsequently, the data was used to drive the feathers, which fluttered and glowed in various ways.
G AND H The assembled array of steel plates formed structural enclosures, spatial boundaries and ‘luring’ elements. Embedded within this array, the sensory network monitored immediate and adjacent territories, routes and lines of approach, and logged activity in these zones as data on a microprocessor. Various intensities of ‘blush’, related to the history of sensory data and live stimuli, were witnessed. As trends began to emerge from the data set, it was possible for Blusher to make behaviour predictions with greater certainty and respond with increasing confidence. The research demonstrates how the use of historical data in relation to real-time activity allows systems to extend beyond being merely reflexive to being adaptive.
Case study Folded surfaces as articulated roof and landscape
EMERGENT/Tom Wiscombe – MoMA/P.S.1 Urban Beach, Queens, New York, 2003.
The P.S.1 Urban Beach, realized in the PS1 Contemporary Art Center courtyard, was based on two distinct but interrelated systems: the Cellular Roof and the Leisure Landscape. The landscape integrates various programmatic elements such as long lap pools, furniture for sitting and lounging, and promenade catwalks at different heights. Also, at key points the landscape begins to adapt into structural supports for the roof. These behaviours are integrated into a coherent ‘gradient’ of use, spilling out rhizomatically into the courtyard, resolving the space into microclimates and passageways.
A The Cellular Roof necessitated creating a long-span structure through a non-hierarchical structural patterning of distinct, but interlaced, units, or ‘cells’. The location and geometry of each cell was determined by local shading requirements, by its required shear and moment reactions, and by the behaviour of neighbouring cells.
B The expanded aluminium-skin cladding was generated using minimal surface geometry, primarily conoidal and parabolic surfaces. These were generated by ‘lofting’ straight-line segments with parabolas or rotated-line segments, creating a slight warp to each panel. This warping, and the associated vaulting, stiffened the panels against sagging. The warping was adopted in the meshwork of the material itself, and therefore the panels could still be unfolded flat and water-jet cut for economical manufacture.
C One of the goals of this project was to integrate issues of fabrication and erection into the design process. As a temporary-event roof needing to be designed, manufactured and installed in just two months, the project was forced to jump directly from conceptual design to shop drawings – a feat made possible by digital-fabrication techniques. The key was to avoid designing a fixed shape and concentrate on creating a controlled geometrical logic which could adapt easily to changes in structural stresses, scope, programme and other conditions.
D The interconnected cells operated in alliance, enabling large, clear spans and forming a structural ‘ecology’. A crenellated second skin wraps these elements into a unified shade structure. At night, however, this provisional body transforms back into an atmospheric light-emitting ‘swarm’, characterized by its cellularity.
E Urban Beach installation complete and in use.
