Designing more-than-human thermal comfort: bio-inspired evaporative cooling in porous facade components for cavity-nesting wild bees

Urban surfaces such as Facades and rooftops are critical mediators of microclimatic conditions in cities, influencing the thermal comfort of both human and non-human inhabitants. Within a more-than-human design perspective, these surfaces may be understood as interfaces where microclimatic regulation can support ecologically relevant funtions, including nesting habitats that moderate microclimatic extremes for wild bee species in dense urban environments. This study builds on prior research into additive-manufactured (3D-printed) porous cellular geometries—specifically Triply Periodic Minimal Surfaces (TPMS) and Adaptive Density Minimal Surfaces (ADMS)—developed as structural envelopes for nesting tubes intended to mitigate heat peaks experienced by cavity-nesting wild bees under urban heat island (UHI) conditions. These species experience metabolic stress when internal cavity temperatures (T nest ) exceed 35 °C and face lethal risks above 40 °C. Previous experiments showed that such geometries can attenuate internal temperature fluctuations by up to 1.6 K compared with conventional materials, although passive geometric performance alone proved insufficient during extreme summer conditions. To enhance thermal regulation, a bio-inspired evaporative-cooling strategy was developed, modelled after the droplet collection and retention behaviour of Apis mellifera . Here, the honeybee is used solely as a biological analogue for water-management mechanisms, rather than as the species under investigation. Comparative field tests in Stuttgart, Germany, evaluated small-scale water-supplied (sWS) and control (sC) samples alongside traditional nesting materials. There resultsinformed the design of full-scale Facade panels—a water-supplied (pWS) and a control (pC) variant—later tested in a climatic chamber simulating heatwave conditions. Across experiments, pWS achieved mean temperature differentials (ΔT) of 8.6–10.2 K relative to pC, indicating the technical potential of evaporative cooling to reduce microclimate thermal stress in biologically sensitive cavities and to inform climate-responsive architectural surface design.