Use of 3D tessellation in curtain wall facades to improve visual comfort and energy production in buildings

In the vast majority of new buildings, energy and comfort requirements are met mostly by active systems that are often expensive, energy intensive, and complex to maintain. At the same time, advances in the use of digital tools for the design and fabrication of unitised curtain wall systems have substantially reduced the costs associated to non-planar surfaces in building envelopes. As a result, buildings deploy an increasing level of surface geometry articulation that is mostly used for decorative effects. By and large, the flourishing of a new formal vocabulary, enabled by digital tools, rarely translated into buildings that perform better. The research proposes the use of non-planar surface geometries for precise calibration in tilt angle and orientation of individual panels in curtain walls, as an effective passive design strategy. The goal is to improve visual comfort for users, limiting potential glare without the use of shading or blinds and, at the same time, to provide high potential for PV production without negatively affecting daylighting levels in the building interiors. The study explores four families of three-dimensional geometries, based on size limitations and other design constraints typically associated to unitized curtain wall systems. The investigation takes into account aspects such as local climate data, orientation, glass properties, morphology of the façade unit, indoor visual comfort, energy efficiency and energy production. Results show that all four families can be optimised to meet LEED requirements of sDA > 50% and ASE < 10% in office buildings, delivering better performances when compared to a flat facade.