National Centre of Competence in Research Digital Fabrication

Abstract Façades are the primary interface controlling the flow of solar energy in buildings and affecting their energy balance and environmental impact. Recently, large‐scale 3D printing (3DP) of translucent polymers has been explored as a technique for fabricating façade components with bespoke properties and functionalities. Transmissivity is essential for building facades, as the response to solar radiation is crucial to obtaining comfort and greatly affects electricity and cooling demands. However, it is still unclear how 3DP parameters affect the optical properties of translucent polymers. This study establishes an experimental procedure to relate the optical properties of PETG components to design and 3DP parameters. It is observed that printing parameters control layer deposition, which governs internal light scattering in the layers and overall light transmission. Moreover, the layer resolution determines angle‐dependent properties. It is shown that printing parameters can be tuned to obtain tailored optical properties, from high normal transparency (≈90%) to translucency (≈60%), and with a range of haze levels (≈55–97%). These findings present an opportunity for large‐scale 3DP of bespoke façades, which can selectively admit or block solar radiation and provide uniform daylighting of a space. In the context of the building sector decarbonization, such components hold great potential for reducing emissions while ensuring occupant comfort.

High-performance facades play an important role in achieving Net-Zero goals by 2050. As a facade manufacturing technology, 3D printing offers the opportunity to create site-specific and high-performance building envelopes. In this manuscript, the thermal performance of components fabricated with different Material Extrusion methods is studied experimentally, and the fabrication time is calculated, thereby examining both performance and fabrication viability. More specifically, this manuscript investigates the thermal performance of 3D-printed facades using Hollow-Core 3D printing (HC3DP) and explores the potential of this novel approach in creating thermally insulating, lightweight, and translucent building envelopes. The research compares the thermal resistance of HC3DP specimens to conventional material extrusion methods, such as desktop 3D printers, and granular-based, large-scale pellet extrusion. Different methods are used to determine the thermal resistance of specimens, including the dynamic thermal conductivity measurement for the desktop 3D-printed (3DP) specimens, and the steady-state hot box heat flux meter approach for HC3DP. The results demonstrate that HC3DP enables lower Thermal transmittance (U-value)s at lighter weight and faster printing speed, making it a promising avenue for further research. Additionally, the combination of HC3DP with aerogel is shown to create ultra-lightweight and thermally insulating 3D-printed facade elements. The potential of this new facade technology is also highlighted in comparison with established facade systems. All in all, the manuscript provides insights into the thermal performance of 3D-printed facades at different printing resolutions and emphasizes the importance of printing time and material consumption in determining the most promising 3D printing approach for lightweight and thermally insulating facades.

The challenge of building sector decarbonization has driven an integral rethinking of the way we design and build facades. Recently, large scale 3D-printing has emerged as an alternative manufacturing technique for novel facade components aiming at high operational efficiency and low environmental impact. Focusing on translucent polymer 3DPFs, this study tackles the challenges of modeling thermal and optical effects in geometrically complex components where interactions across multiple domains and scales occur. In particular, we introduce a novel method for modeling the irregular thermo-optical properties of 3DPFs, capable of capturing relevant effects often out of the scope of traditional modeling approaches. Our model accounts for geometry-dependent physical effects ranging from millimeter-scale fabrication details that impact optical behavior to centimeter-scale geometric features influencing heat and radiation transfer, extending up to the meter-scale implications for the building application. By employing computational techniques such as ray-tracing, computational fluid dynamics, and finite element analysis, we establish a model that offers detailed thermal and optical analysis to support performance-driven design iterations. Finally, demonstrating this approach in an office building context, we show that 3DPFs can match the performance of double glazing with dynamic shading, providing effective solar and thermal management over the year. This is achieved in a single, mono-material component with no active control, suggesting 3DPFs are a promising direction for low-environmental impact facade design.

The Advances in Architectural Geometry (AAG) symposia serve as a unique forum where developments in the design, analysis and fabrication of building geometry are presented. With participation of both academics and professionals from the fields of architecture, engineering, computer science and mathematics, each symposium aims to gather and present practical work and theoretical research that responds to contemporary design challenges and expands opportunities for architectural form. This report summarizes the AAG2016, the fifth edition of the symposia hosted by the Swiss National Centre of Competence in Research (NCCR) Digital Fabrication at ETH Zurich from 9 to 13 September 2016.