ABSTRACT
Parametric design is a computer-based design approach that treats the geometric properties of the design as variables. The dimensions, angles and geometric properties (like curvature) remain malleable as the design progresses. Although at any time the “parametric model” displays a determinate shape according to the set of currently chosen values, the essential identity of the parametric design resides in the malleable object’s topology rather than its momentary determinate shape. This means that the design consists in the relationships that are maintained between the various elements of the composition. In fact the parametric design model is conceived as a network of relations or dependencies. This way of building up a design has the important advantage that the build-up of complexity and the detail resolution of the design can progress while simultaneously maintaining the malleability to adapt to changing requirements as new information is fed into the design process. The generation of alternative options remains viable and economical deep into the detail design without requiring abortive modeling and drafting work. This parametric malleability is advantageous both for the sake of continuous design adjustments as the design progresses, and for the sake of the generation of options and variations. The parametric model can be conceived as general building plan or geno-type for the generation of many different versions or pheno-types that might co-exist (rather than substitute each other as options). Optioniering thus leads to versioning. Mechanical repetition is being replaced by mass customization. Versioning might also be applied within a single building design via the versioning of components, via “generative components”. The components adjust their individual shapes in relation to their placement within the encompassing model. These components are small parametric models, i.e. sets of interdependent parts with adjustable shapes. The component adapts to (and fits into) local constraints via the adjustment of its internal parameters. For instance an array of façade components—complete with glazed openings, frames and fixing details—might be made to populate the surface of a volume with changing curvature. The components are to be set up in such a way that they auto-fit to the surface. Each component will assume an individually fitted “pheno-typical” shape, on the basis of the same underlying “geno-type” Thus parametric design is a powerful methodology to achieve a new architectural morphology, namely a morphology of continuous differentiation. However, the potential for such differentiation is not confined to the achievement of scaling and geometric fit with respect to complex forms with continuously changing surface curvature. This kind of differentiation might also be driven by performance parameters like structural parameters or environmental parameters like sun exposure or wind-loads. For instance the opening within a façade panel or the shape of a shading element might vary according to the differential sun exposure of a curved façade at each point of its surface. The parametric designer might set up the following dependency: the higher the sun exposure of a certain surface patch, the smaller should be the opening of the façade component at this location. A sun-exposure map imported from an environmental analysis tool might then deliver the data input for the component differentiation. The sun-exposure map is thus being “transcoded” into a differentiated field of façade panels that “optimizes” the sunlight penetration within brackets set out by the parametric design. The resultant façade articulation is thus a function, mapping or indeed a representation of the façade’s differential exposure to the sun.
