A Parametrically-Generated Curtain Wall

The sunshading system for Northeastern University’s new Interdisciplinary Science and Engineering Complex is PAYETTE’s first parametrically-generated curtain wall system. Utilizing Grasshopper, Rhinoceros’ parametric plugin, and AutoCAD, the exterior design team worked to set the baseline conditions and outset geometries of the sunshading system. In that effort, the team composed the definitions needed to properly generate and document a workable 3D model for solar performance analysis.

Next, the 3D model was brought into Revit to be integrated into the drawing sets and to be given to the design assist subcontractor Permasteelisa North America (PNA). PNA’s fabrication department, Scheldebouw, then utilized a wireframe variance of the 3D model, created by PAYETTE, to produce shop drawings for fabrication.

The strength and versatility of the parametric approach lie heavily within its power to iterate with speed and accuracy. The written definition gave the design team the ability to customize the shading profile extrusion and, at the same time, gave control over the exact number of divisions per unitized curtain wall panel while reducing modeling inaccuracies.

During the pre-design for Design Assist (DA), numerous shading profiles, divisions and spacing were exacted to find the optimal arrangement and shape of the sunshading fins.

The design team worked closely with PAYETTE’s 3D Visualization Department to accomplish this task. A custom solar mapping script called “NUKE” was utilized to generate the solar shading and to calculate the reduced radiation upon the curtain wall system.

With over 480 vertical fins situated across the building’s western façade, we needed a systematic approach to the design. The parametric approach set the framework. Because of the scale of the design, the sunshading system was conceived in one holistic vision. Through the modeling process, the exterior design team was aware that most of the design items would have to be addressed through the DA process with the fabricators and our consultants. Some of these items include the aero acoustic performance of resonance bracing, fastener locations, outstanding cantilever loadings, visual perception and solar shading. The systematic approach fostered a high level of resolution and ensured the accuracy of the 3D model, which was required for it to be useful during fabrication.

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