27 februari 2018

Esthetical review of free-form glass façade design using VR experiences

With the ongoing developments in the glass industry, the possibilities for glass façades are rapidly increasing. Architects seem to benefit from this, by designing façades in free-form shapes that were almost impossible to realise in glass only some years ago. In this blog, I will show you the possibilities of free-form glass façade design using VR-experiences.

Free-form shapes
One example of a free-form shaped façade is the double curved façade of Depot Boijmans van Beuningen, designed by MVRDV and soon to be realised as a public art depot featuring exhibition halls in Rotterdam. This spherical shaped building will be acting as one huge mirror. But how do you manage the esthetical quality in these kinds of façades? 

One of the major issues is the alignment of the glass to act as one smooth surface, including tolerances. Now, with help of advanced computational design and virtual reality (VR), the architect is given the opportunity to determine what is aesthetically acceptable. At the same time, the client can determine what from his point of view is acceptable, since a smoother surface inevitably affects the overall price for tightening up the tolerances. VR-experiences could help in the dialogue between contractor, architect and client in an early stage of the design process, to satisfy design conditions like costs and construction possibilities. 

Parametric design
Due to the complex shape of this façade and the highly repetitive panelling, the use of the computational design solution parametric design was chosen.

Afbeelding: Boijmans Van Beuningen Blog Teun

In parametric design, the mathematical definition of all glass panels, curtain wall systems and elements were rationalised in design rules (see the picture above). These rules where taught to the computer using programming. The parametric approach provides a flexible project definition that allows for easy modification and improvement of the shape and the opportunity to create different variants in an iterative design process.

Afbeelding: Tekening Boijmans van Beuningen

Virtual Reality
Reviewing variants using VR gives the designer instant feedback so decisions can be quickly made for a new variant. For instance, for a project like the Depot Boijmans van Beuningen Museum there are design topics like panel distribution and joint width (smaller joints might not always be better). But also to judge which production tolerances deserve more attention during the glass panel production. If the overall surface has to look smooth, the tolerances in curvature might be more important than those for the joints. Especially for this mirroring façade, being in control of tolerances is of extreme importance, since tolerances are directly visible as a result of reflection distortion. Deviations will occur in panel width, height and thickness. In addition, hot bending of glass adds even more diverse tolerances like out of pane and twisted bending. The lamination process will introduce some misalignment of the single and even more for the double glass panes. Coatings might introduce some difference in colours for single and double glazing. Add this together and the esthetical judgement of the overall VR-model is maybe the only way to accept the quality before construction starts. 

There will be many projects in the future that can benefit from this design process. We could create renders which can be reviewed in VR, even by just using a simple Google cardboard. The experience of differences between the theoretically perfect façade and the façade with tolerances on the glass could avoid quality discussions and increase the quality of tomorrow’s free-form façades. 

A step even further would be to scan all panels after production, analyse them, and then tune and optimise the placement position of each unique panel. This way, tolerances of side by side panels may compensate each other so the mirrored image will be more continuous and the joints more straight to get an “as built” VR model!


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