advanced building skins 14 | 15 June 2012 - lamp.tugraz.at - Graz ...

Advanced Building Skins
6 Parametric Modeling as Key to a Successful Process
A project like the one presented here, with exactly 14,309 individual components of which no two are
the same, is only feasible with parametric modeling, i.e. abstracting the numerous different geometric
conditions into a considerably smaller set of rules and rendering those into a set of tailor-made CAD
tools. For this to succeed, a consistent design and construction principle is necessary in the first place,
as each exception to the rule drives up complexity and effort by a high degree. Secondly, the digital
process must not stop with the geometry model but extend into fabrication: Only with a continuous
digital chain from design to production, the sheer amount of individual parts becomes manageable.
In case of the Kilden Façade, only two types of Timber/Steel connections exist that can adapt to the
varying conditions throughout the wall by a set of defined rules. Furthermore, through the concept of
embedding complexity in the building parts (see 3.1) the adaptation even takes part in the individually
milled timber beams, so that the steel connectors and any other parts necessary can be “off the shelf”.
And this is where the material decision becomes key to success: 56,000 precise seat cuts could not
have been milled into steel tubes.
Figure 9: Two parametric connection details that adapt to different geometric conditions by individual cuttings in
the timber beams (designtoproduction)
Thus, an elaborate prefabrication process that engages early in the building process – possibly even
negotiating details of the design to ease fabrication while maintaining the design intent – combined
with a continuous digital production chain from 3D model to CNC-fabrication can help to reduce cost
and effort while ensuring a high quality of the result. Some of this money has to be spent earlier:
When the first parts arrive on site – in fact, even when the first material is ordered – most of the work
has already been done. While this should be most welcome, as it makes the building process much
more predictable and not least highly reduces the work on site, it is antipodal to traditional processes.
This seems to be one of the main obstacles for processes like the one presented here to be applied
more frequently today.
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