This study explores the design possibilities with knitted architectural textiles subjected to wind. The purpose is to investigate how such textiles could be applied to alter the usual static expression of exterior architectural and urban elements, such as facades and windbreaks. The design investigations were made on a manual knitting machine and on a CNC (computer numerically controlled) flat knitting machine. Four knitting techniques - tuck stitch, hanging stitches, false lace, and drop stitch - were explored based on their ability to create a three-dimensional effect on the surface level as well as on an architectural scale. Physical textile samples produced using those four techniques were subjected to controlled action of airflow. Digital experiments were also conducted, to probe the possibilities of digitally simulating textile behaviours in wind. The results indicate that especially the drop stitch technique exhibits interesting potentials. The variations in the drop stitch pattern generate both an aesthetic effect of volumetric expression of the textile architectural surface and seem beneficial in terms of wind speed reduction. Thus, these types of knitted textiles could be applied to design architecture that are efficient in terms of improving the aesthetic user experience and comfort in windy urban areas.
Although textiles are not the most common building material, several good examples of textile architecture exist. An influential architect and theorist Gottfried Semper has claimed that the wall originates from woven structures, such as bast mats. In his seminal book “The four elements of architecture”, he postulates that the true function of a wall is to serve as an enclosure instead of being merely a load-carrying structure (Semper, 2010). Textiles can, however, also be used to carry structural loads. Architect and engineer Frei Otto is perhaps the most well-known designer of tensioned, load-carrying architectural constructions. The work of Krüger (2009) demonstrates that the area of textile architecture shows great variation and richness of the design solutions, both for tensile and non-structural textiles.
Most examples of textiles in architecture use a woven textile, while the knitted structure is not as widely explored within this context. Compared to a knitted textile, in a woven structure the behaviour of the textile is more directly linked to the thread's strength and stiffness because the threads in the weave are almost straight. In a knit, the thread is forming linking loops. As a result, bigger deformations of the textile occur when forces are applied and the loops are stretched out.
Although scarce, examples of architectural designs and research work on knitted structures exist. For instance, the myTread and Lumen installations by Jenny Sabin (Sabin, 2013; Sabin et al., 2018), Isoropia and The Tower developed at the CITA - Centre for Information Technology and Architecture in Copenhagen (Deleuran et al., 2015; La Magna et al., 2018; Ramsgaard Thomsen et al., 2019), the Knit Tensegrity Shell project by Gupta et al. (2019) and Sean Ahlquist's sensory architecture (Ahlquist, 2015, 2016). These structures are, however, with some exceptions, mainly based on the principle of tensile textiles, in which the material is stretched until the structure is virtually stiff. They are designed to remain static and, in terms of geometric expression, are bound to an anticlastic surface typology only.