Geometry and Technology
Zaha Hadid’s interest in form and its geometric definition goes back more than thirty years; a central preoccupation of ZHA has therefore been the exploration of complex geometry, its representation and increasingly, over the past ten years, its translation into physical form through built projects. The design language at ZHA has continuously evolved, but its central interest has remained focused on concepts of dynamic architectural and urban form. Architecture is understood as having a motion or movement embodied in its design, which separates it from the conventional static of traditional form language. In recent years this has been characterized by curvilinear geometry and complex, mass-customized components that are at the heart of contemporary architectural discourse today. Together, these design aspirations require considerable computational skills that are beyond the average use of CAD or 3D visualization modelling.
In keeping with the firm’s ideals of research and experimentation, ZHA has chosen to not advocate a dogmatic approach to software technology within the office. In other words, while the introduction and dissemination of tools and technology must necessarily be controlled in a larger firm, at ZHA a number of similar tools are used in each stage of work, either because different teams have different experiences of technology, or because one type of project is more effectively tackled on one platform rather than another. In most cases, multiple tools are used concurrently, whereby the effort of supporting multiple platforms is clearly outweighed by the advantage of being able to tap the best tools and technologies each platform has to offer.
Parametric Design Language
Under the leadership of Zaha Hadid and Patrik Schumacher, ZHA has developed an approach to building design which makes consistent use of powerful computational design technologies available today – in fact, the design language of the office has evolved in tandem with technology, constantly pushing the boundaries of geometric expression while developing the technical capability to faithfully capture and execute a design. The integration of design intention and accurate, efficient project delivery is achieved through a digital codification of design as a series of related and interconnected geometric operations, in which families of design solutions can be rapidly generated by controlling associative geometries and driving parameters. Downstream, design geometry can be articulated as families of self-similar components that can be produced by available CNC fabrication technologies, and rationalized to achieve constructability informed by cost, risk and aesthetics. This process-wide “parametric language” allows ZHA to rapidly and efficiently tackle complex design problems and produce a flexible range of viable results in a short amount of time, while being able to effectively deliver building projects. As a result, most architects within ZHA have a high degree of computational literacy and dexterity ranging from traditional CAD skills through 3D parametric modelling and scripting, and many are experienced in constructing projects through digital coordination. Combined with an increasing number of employees who are specialized in design-computation, this level of digital fluency ensures that the firm can make the fullest use of the digital design tools available – with the ability to customize and tailor these tools to the firm’s design requirements, and not vice-versa.
ZHA has a widely available “general scripting” knowledge base spread more or less uniformly around the office and the project teams. This consists in general of Maya MEL and VB scripting in Rhino (and, more recently, Digital Project) as well as the ability to produce and replicate sophisticated parametric reconfigurable models. If scripting and programming is understood as knowledge-capture that can be repeatedly applied, then “parametric modelling” can be seen as a form of visual programming that in many cases accomplishes the same thing, but without the need for the user to learn extensive scripting syntax and grammar.
Design and Computation Research
Beyond general parametric modelling, ZHA also actively undertakes project-independent research, developing computational design tools and geometry articulation algorithms through an in-house research team. This team is made up of architects and designers who have particular interest and skills in formal software development. The team members divide their time in periods where they are directed to work on developing computational solutions independent of any project, and at other times being associated with, or deployed onto, specific project teams that may require a specific design-computation solution on a short- or long-term basis. The tools developed by the research group can be considered as “scripts” or more advanced “plug-ins”, are for the most part developed on top of the various design platforms that ZHA uses. More recently, the research group has also begun to implement scripts in the form of Rhino Grasshopper parametric constructs, as well as more strategically investigate a broader integration and interoperability of data between the various design platforms in the early design stages, and data transfer into the downstream production phases.
Integrated Digital Building Delivery
The use of 3D modelling and digital data on projects in advanced stages of development and construction has also been steadily growing. In the earliest cases, 3D models were only used to develop project geometry internally. In addition to traditional 2D documentation, ZHA has addressed its need to develop and document complex projects by implementing a documentation process, which can be referred to as Building Information Modelling (BIM), although not always in the strictest definition of the term. In the last few years, projects have begun to employ BIM-capable 3D tools such as Digital Project and Revit as a central geometric coordination platform.
Another important factor is the rapidly increasing growth in clients’ requirements for projects, and, in particular, the reduction in turn-around time for submittals ranging from design options to RFI responses, and breadth and precision of information required by the client during the design phase. In most cases, the type of information required can only be processed and provided if the project in question is built primarily on a digital platform that can be efficiently interrogated for information, and tracked and audited for design transactions and changes. Digital information is exchanged in different ways depending on the recipient, the phase of work and scope of the information and – not least – the form of contract involved during procurement and construction. Data is actively exchanged collaboratively at all stages of a project in order to expedite project development, particularly between architect and consultants during the design phase. Contractually binding information can be issued to contractors as 2D geometry in the form of AutoCAD (DWG) or Microstation (DGN) files or as 3D models in Rhino (3DM), Digital Project [CATIA] (CATPart) formats; PDF files of drawings are considered equivalent to paper and the digital content therefore not suitable for fabrication.
In contrast to preconstruction, exchanges of information during the procurement and construction are carefully tracked so that any changes to the contract documents (geometric definition and scope of work) can be audited as simple information updates or actual change orders, which can trigger additional cost and associated allocation of responsibility. In each case, changes in digital information are carefully logged and revised files issued which supersede previous versions. Updated geometry is coordinated in either 2D drawings or 3D models to determine impact of change on the project and required effort to synchronize project documentation.
A First 3D Coordination Project
One of the first projects to employ 3D digital coordination at ZHA was the Glasgow Museum of Transport. A Digital Project model was used to integrate the primary structure (steel) with the exterior and interior cladding systems, as well as the main mechanical systems ducts and plant equipment. The steel members in the model were specified by the structural engineer and subsequently detailed with Tekla XSteel to provide all connections. This detailed steel model – essentially a 3D shop drawing – was used for the fabrication of the steel components. Its high level of detail (including nuts and bolts) made it highly valuable for the coordination of interior finishes and ceiling geometry to the steel.
While the 3D coordination played only a partial role on the Glasgow project, it clearly has opened the way for ZHA to expand its use of 3D BIM across the firm, in different roles as project needs dictate. Traditional 2D drawings remain part and parcel of project definition and delivery, as they efficiently convey design intention by depicting typical conditions (for example, in sections and details) while allowing the 3D model to define the complete geometric scope for the project to which said details must be applied. Furthermore, 2D drawings are still required for most government approval processes and submittals. At the same time, many countries and government agencies now specify the need for 3D models (often in neutral formats such as IFC – Industry Foundation Classes) as part of public project submittals. While it is unlikely that 2D drawings will disappear, it is clear that the liberation of geometry from the required constraints of 2D representation goes hand in hand with contemporary architecture’s preoccupation with complex geometries that can only be represented in three dimensions.
Digital Form Definition and Mock-ups
A similar 3D coordination process is currently being used for the SOHO Galaxy project, a large commercial mixed-use project now under construction in Beijing. The project can be considered representative of the digital design and documentation techniques currently being developed and employed by ZHA. During the early concept phase, the project was designed using “subdivision surface” technology within Maya to produce the underlying master surface “parametric driver” geometry that would define the design intention for the project – in this case, a set of four egg-shaped volumes that are fluidly interconnected to create a single building mass. This “driver” geometry forms the basis for a 3D digital coordination process using Digital Project and defines all downstream project geometry, such as slab profiles, facade contours and cladding surfaces. For example, the facade of the SOHO Galaxy project is generated by slicing the “driver” surface horizontally at each floor, producing horizontal bands of inset glazing divided by rings or “fascias” of white surface geometry that provide a reference to the original underlying shape.
As part of the design development process, ZHA and the client elected to build a series of facade mock-ups in different materials to assess geometric complexity, contractor capability in China, as well as material performance, constructability and aesthetics. An area of the project was chosen which allowed the team to test the broadest possible set of geometric conditions. A tender package for the mock-up was issued to fabricators as a combined 3D model and 2D drawing documentation set. The same identical area of facade geometry was executed in sheet metal, steel plate, fibre-reinforced plastic (FRP) and glass-reinforced concrete (GRC) panels.
The mock-up process led to the choice of facade material for the project, in this case, aluminium sheet metal panels. The geometry of sheet metal ensures that the manufacturing process minimizes the use of expensive forming techniques such as moulds or pressing, thus keeping the cost down and expediting execution. Using such single-curved surfaces to implement sections of originally double-curved geometry (the “driver” surface) implies of course approximation or rationalisation of the original shape. However, at the scale of the panels and fascia width, the visual difference per fascia band is negligible, and with the exception of highly curved areas, allows about 95 % of the building facade to be implemented in sheet metal geometry, with considerable savings to the project.
Intercontinental Building Integration
Digital coordination and execution processes also benefit fast-track projects being designed remotely. The Seoul Dongdaemun project is a large cultural facility currently under construction in Korea. The building’s detailed design was conducted between ZHA in London and the Executive Architect team in Seoul, using 3D Digital Project models to integrate project geometry created simultaneously in London and Seoul. This allowed the project to be designed and detailed faster and in part with greater independence, as the building systems were developed in parallel on both continents rather than sequentially. This was achieved by establishing a common envelope surface (the “parametric driver” described previously) which served both as the definition geometry for the external cladding systems as well as the interior boundary for the structural and mechanical systems inside the building.
The team in London led the overall definition of the project’s parametric infrastructure, and worked in collaboration with the consulting firm Evolute to develop a geometric tessellation of the envelope surface that resulted in a family of self-similar cladding panels. These were optimized to control cost by minimizing the number of single- and double-curved panels while retaining a visible aesthetic of surface continuity. Meanwhile, the team in Seoul used the same envelope surface, with specific offsets and subdivisions, to generate the internal steel skeleton, the external envelope’s supporting structure and a model of the building’s MEP systems to achieve a full building integration model. The external envelope geometry and internal structure and systems models were subsequently integrated into a single model in Seoul, which is currently being used on site for construction coordination.
