Breathing skins workshop: A hands-on investigation of bio-inspired foldable structures for temperature and humidity control in buildings

Geometrical and material properties of plant leaves are known to influence heat/moisture dissipation. In many species, exposed “sun” leaves are typically more dissected and possibly better convective heat dissipaters than entire shade leaves. By affecting the overall leaf boundary layer, lower-scale morphology patterns such as toothed edges can also have an important role in heat/moisture dissipation, as pointed by experiments with wetted paper models where outward teeth increased evaporative dissipation rates. Additional leaf morphological traits potentially influencing dissipation are surface corrugations, textures, trichomes and sunken stomata. Such structures can work as “dissipative” or “retaining” geometries depending on how they couple with environmental conditions and modulate leaf boundary layer. The oneweek intensive Kosmos interdisciplinary workshop at the cluster Image Knowledge Gestaltung (Berlin) was an opportunity to explore leaf design and achieve microclimate control for potential applications in technology, specifically building facades. The "Breathing skins” concept was to apply shape-related leaf dissipation strategies into folding structures that can be produced in a typical “maker-lab” setting. After a thematic introduction, participants were asked to target evapotranspiration behavior and shape-change characteristics derived from leaves, and to deliver prototypical designs using a set of prepared materials. Workshop results show the transfer of new findings in research on evapotranspiration of biological plant leaves into 3D structures for technical application. The biomimetic approach taken delivered a first translation of design abstracted from leaves into the realm of foldable geometry, for future development and technological transfer to useable products in architecture, building and fluid-assisted heat transfer systems in general.