Implementing hygromorphic wood composites into responsive building skins

Natural organisms which employ inherent material properties to enable a passive dynamic response offer inspiration for adaptive bioclimatic architecture. This approach allows a move away from the excessive technological intensity of conventional ‘smart’ building systems towards a more autonomous and robust materially embedded sensitivity and climatic responsiveness. The actuation mechanisms of natural responsive systems, such as moisture-induced movement of bilayered conifer cone scales, can be replicated to produce artificial moisture-sensitive (hygromorphic) composites with the response driven by hygroexpansion of wood. The developed low-tech low-cost hygromorphic materials are capable of pre-programmable reversible mechanical response to changeable levels of ambient humidity and moisture. Previous research into hygromorphs has provided the theoretical basis for rational selection of composite configurations, including the choice of material for each layer, their thicknesses, orientation and type of bond. This paper explores the opportunities and challenges for building integration and architectural functionalisation of the responsive wooden composites. The suitability of different material production techniques and viability of potential applications is established through a detailed programme of experimentation and long-term field tests