Design of a hybrid adaptive sunshade with a knitted textile and shape memory alloy

The higher complexity of adaptive façades with respect to conventional static façades hinders their applicability to the built environment. To address this, passive solutions aim at lowering the number of components while preserving the benefits of these systems. In this paper the design of a two-component passive dynamic sunshade that combines Shape Memory Alloys (SMAs) and knitted textile is presented. The novelty resides in the way the textile acts as an active member of the system, counteracting the SMA when in its martensitic (inactive) stage. The properties of the textile and design of the systems repeating movement are determined through mechanical testing. With nodal thermal modelling the main drivers of the SMA spring temperature have been studied. Results show that it is possible to achieve a promising range of movement with the proposed system, but both the textile and the spring could be more optimized to achieve a larger stroke. Results of the thermal analysis highlight that there is a need to concentrate the solar radiation on the spring for it to be independent from the outdoor temperature and work solely with solar radiation. Overall, the presented research expands the knowledge on the design of low-components-based passive sunshades and showcases an example of how textile can become an active member of the mechanical system.