Tuning the Solar Performance of Building Facades through Polymer 3D Printing: Toward Bespoke Thermo‐Optical Properties

Abstract

sector accounts for 34% of energy demand and 37% of energy-related CO 2 emissions globally. [2] In buildings, a major portion of the footprint concentrates in the first year of the life cycle and results from embodied emission of material and components. This relative contribution is expected to reach values as high as 50% of the total emissions as energy efficiency in buildings increases. [3] At the moment, despite the continued power sector decarbonization and the adoption of climate-change mitigation policies, buildings remain offtrack to achieve carbon neutrality by 2050. [1] Facades constitute the main building boundary between external and internal environments, controlling the flow of energy and matter inside buildings. For this reason, they considerably impact the environmental conditions of indoor spaces, user satisfaction, and operational efficiency. [4] Therefore, improvements in the performance of building facades are critical to meet most of Net Zero Emissions by 2050 scenario reductions in energy use. [5] To meet the performance requirements prescribed by the building codes, advanced facades systems have been proposed, which can tune their behavior in response to variable boundary conditions [6][7][8] and feature smart materials allowing integration of and switching between multiple functionalities. [9][10][11] Apart from the operational 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.

Influence of 3D Microstructure Pattern and Infill Density on the Mechanical and Thermal Properties of PET-G Filaments

“…This phenomenon may mainly be associated with possible printing failures arising at lower percentage densities that affect the U-value, as seen in Figure 11, which shows the post-test state of the Hilbert curve geometry specimen with 5% density. Analogous behaviour was also identified in the study [36] using a robotic polymer extruder, where thermal transmittance (U-value) varied from 1.7 to 1.0 W/(m 2 .K) only by changing the infill density. The best performance was obtained using higher infill densities, which is consistent with the values obtained in this study, where the U-values vary between 1.7 and 1.8 W/(m 2 .K) for 5% infill density and 0.4-0.8 W/(m 2 .K) for 25% infill density.…”

Printing thermal performance: an experimental exploration of 3DP polymers for facade applications

“…Finally, to fully characterize the performance of translucent 3DP facades, the influence of solar radiation on the heat transfer needs to be investigated, considering the geometrical complexity of the elements. 3D printing creates anisotropic elements with layered resolutions, resulting in angle-dependent, directional transmission of solar radiation [47]. By coupling thermal and optical domains, we can define seasonal/temperature-dependent solar heat gain coefficients (SHGC) and U-values, which would better capture the component behaviour.…”

A Holistic Modular Solution for Energy and Seismic Renovation of Buildings Based on 3D-Printed Thermoplastic Materials

“…This material was selected due to its biocompatibility, Sustainability 2024, 16, 2166 6 of 28 UV resistance, mechanical performance, and market availability [42,43]. PET-G is also used as a building façade material in some studies regarding 3D-printed building façade solutions [44,45]. Since PET-G is non-toxic, bio-compatible, UV-resistant, and food-safe, it is used in healthcare and food industries [46,47].…”