Material and Structural Optimization of Novel Phase-Change Thermal Diode for Dynamic Building Envelope

Passive energy savings through the building envelope represent a critical strategy for reducing both energy consumption and carbon emissions. However, traditional technologies are limited by cumbersome control mechanisms and narrow adjustment scopes. To overcome these limitations, we propose a novel phase-change thermal diode with an enhanced unidirectional heat-transfer capacity. This thermal diode utilizes hydrophobic and hydrophilic materials, presenting dual benefits in material fabrication and structural applications. To verify the potential of this approach for building applications, the effect of different hydrophobic materials and vacuum on the performance of the thermal diode were compared experimentally. The optimally formulated material, which is readily manufacturable over large areas, demonstrated thermal rectification ranging from 8.72 to 23.62, thus offering an extensive adjustment range. For structural applications, the thermal diode could be combined with the building envelope to create a dynamic envelope for passive heat dissipation and insulation. Simulation studies confirmed that this novel dynamic adjustment method provides superior adjustment capabilities and achieves greater energy conservation than conventional dynamic methods. Specifically, cooling energy savings between 11.83% and 21.36% were attainable across various climate zones in China. This research fosters cross-innovation in the fields of buildings and materials, serving as a foundational reference for developing dynamic building envelopes.