Design, Fabrication, and Evaluation of Novel 3D-Printed Thermal Metamaterials for Energy Optimization in Sustainable Buildings

Thermal metamaterials represent an emerging technology with high potential for controlling and modifying thermal conductivity, enabling efficient heat flow management. Their application in sustainable buildings contributes to enhancing thermal insulation, reducing energy consumption, and optimizing heat management in low-impact infrastructures. In this study, six novel thermal metamaterials were designed and fabricated—three intended to block heat during summer and three to retain it in winter—promoting thermal comfort in highly energy-efficient buildings, such as those designed under the Passive House standard. The metamaterials were manufactured using 3D printing, combining materials such as polylactic acid (PLA), polyethylene terephthalate (PET), and thermoplastic polyurethane (TPU) combined with a graphene-based conductive filler (TPU+Graphene), along with steel and copper. The thermal conductivities of these materials were experimentally determined, and Finite Element (FE) models were developed to analyze their thermal expansions and contractions as a function of operating temperature, as these effects influence their thermal behavior. Experimental results obtained using a thermal imaging camera exhibited a strong correlation with the values predicted by the FE simulations. Experimental results obtained using a thermal imaging camera exhibited a strong correlation with the values predicted by the FE simulations. Metamaterial 1, fabricated with TPU+Graphene achieved a heat transfer coefficient of U = 0.0001 W/m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>·K in the insulation state and U = 0.82 W/m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>·K in the conduction state, demonstrating effective thermal switching behavior. Finally, a life cycle assessment (LCA) of the metamaterial manufacturing process was conducted, evaluating its environmental impact using the ReCiPe methodology. The fabrication of this metamaterial resulted in impacts of 88.16×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–7</sup> DALY, 5.18×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–7</sup> species·yr, and 307.55×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–7</sup> USD2013 when designed to block heat in summer, and 373.79×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–7</sup> DALY, 0.25×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–7</sup> species·yr, and 453.16×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–7</sup> USD2013 when configured to retain heat in winter. The findings highlight the potential of 3D-printed thermal metamaterials to improve energy efficiency in buildings and advance innovative solutions in thermal management and sustainability.