ABSTRACT
Envelope systems that can passively and autonomously respond to climate conditions are a valuable, sustainable strategy to improve building performance and reduce energy consumption. Wood bilayer shape-change actuators are cost-effective to produce and can be precisely programmed to respond to target environmental conditions, but their response speed is limited by the speed of moisture diffusion. The thicker and mechanically stronger the sample, the longer it takes to respond. Previous research has shown that some improvement in response time can be achieved through the coupling of bilayers and by integrating moisture diffusion channels within the bilayer architecture, but the response speed remains below the level that most occupants desire. In this paper we present an elastic kinetic strategy that can improve the response time of a hygroscopic wood actuator by augmenting the amplitude of the resulting shape-change deformation. The first section examines local biological role models that use elastic systems to achieve kinematic amplification. The second section presents the development of a wood bilayer and its integration into an elastic kinetic mechanism. The third section tests the integration of the elastic amplification mechanism into a proof-of-concept climate responsive shingle system for building ventilation purposes. The presented coupling of elastic components with passive hygroscopic actuators demonstrates faster response times through the increased range of motion of the hygroscopic actuator. The shingle application offers a valuable perspective for system integration within adaptive architectural building components, which can greatly contribute to improved building performance in climate adaptive applications.
