Weather-responsive adaptive shading through biobased and bioinspired hygromorphic 4D-printing.

In response to the global challenge of reducing carbon emissions and energy consumption from regulating indoor climates, we investigate the applicability of biobased cellulosic materials and bioinspired 4D-printing for weather-responsive adaptive shading in building facades. Cellulose is an abundantly available natural material resource that exhibits hygromorphic actuation potential when used in 4D-printing to emulate motile plant structures in bioinspired bilayers. Three key aspects are addressed: (i) examining the motion response of 4D-printed hygromorphic bilayers to both temperature and relative humidity, (ii) verifying the responsiveness of self-shaping shading elements in lab-generated conditions as well as under daily and seasonal weather conditions for over a year, and (iii) deploying the adaptive shading system for testing in a real building facade by upscaling the 4D-printing manufacturing process. This study demonstrates that hygromorphic bilayers can be utilized for weather-responsive facades and that the presented system is architecturally scalable in quantity. Bioinspired 4D-printing and biobased cellulosic materials offer a resource-efficient and energy-autonomous solution for adaptive shading, with potential contributions towards indoor climate regulation and climate change mitigation.