Copyright 2021 © The Bartlett School of Architecture, UCL
The HygroSkin Observatory is an environmentally responsive construct that explores the complex relationship between timber and moisture. Timber is a hygroscopic material – its innate ‘living’ ability to constantly equalise its moisture levels with the surrounding environment results in the continuous transformation of its shape and form. This condition has long been stigmatised in industrial practice. In contrast, this construct celebrates the phenomenon through observation and scientific data conveyance.
The hygroscopically actuated skin is comprised of bi-layer timber veneer components that vary relative to the panel’s cut pattern, both in species and in grain orientation. The veneer panels are mounted onto a bespoke structural timber frame that explores various glue lamination strategies, joinery methods, and CNC milling fabrication.
Observers seated within the cockpit-like structure are immersed in the semi-exposed environment. They can observe current weather conditions portrayed by the shape of the actuated timber skin. For rapid actuation of the skin, an ultrasonic misting system can be triggered manually, and sensors are detecting low humidity or timber deflection.
Long-term movement of the timber skin is captured by a rotating camera on the exterior and data-collecting sensors in the interior. Both observation techniques are combined and conveyed through graphic visualisation on a digital screen visible to observers inside the structure.
The experiment concludes the cut, grain orientation, and species for maximum hygroscopic actuation.
The experiment investigates bi-layer compositions and variations of cut pattern in relation to grain orientation and species.
Explore the interactive model.
The beam model is weighted with the main expected loads in Karamba3D. The centre of mass has been confirmed. The resulting deflections are used to guide joint design.
The position of the surveillance camera on the rotating boom defines parameters used for the design of both the skin subframe and the incisions on the veneer panels.
A machining table made from two laminated layers of 15mm birch plywood has been installed into the HAAS TM3 machines, allowing for stock to be precisely aligned.
Because of its precision, laser cutting was the most suitable tool for the skin incisions. There were, however, issues related to the hygroscopic deformation of beams and panels.
Environmental and material data are gathered using electronic sensors, input into a microcontroller, and split into different channels for analysis and decision making.
The data related to timber curling is measured with flex sensors. As the timber bends, the flex sensor curls by a certain degree and experiences a measurable change in resistance.
An exterior camera is orbiting the structure and capturing the long-term movement of the timber skin.
After two days outdoors, the skin panels were 3D-scanned. The veneer had deformed according to the various typologies of incisions, showcasing the logics of hygroscopic actuation.
Incision typology C: high degree of hygroscopic actuation, increased resistance.