Programmable passive actuation for adaptive building façade design using hygroscopic properties of wood

ABSTRACT

This paper exploits the hygroscopic properties of wood and its passive response to fluctuation of relative humidity to develop a framework for programmable actuation in adaptive building façade design. This responsive shape shifting mechanism is specifically employed for the embedded actuation of dynamic shading configurations. Utilizing the hygroscopic properties of wood in adaptive shading devices embraces passive motion with a low-cost and low-tech approach, as a response to rapid climatic changes. Using physical experiments and image analysis, changes in the deflection and angle of curvature of wood samples in response to fluctuation in relative humidity were measured and tracked. A set of controlled hygroscopic parameters affecting the motion response of wood were deduced, including the fixation position, fixation type, and percentage and location of isolated areas of wood samples, thus achieving more control of response behavior and multiple shading percentages. A parametric script was developed using Grasshopper graphical algorithm editor and Ladybug environmental plugin to simulate shading configurations for the identified control parameters in the summer and winter solstices for an adaptive façade prototype.

KEYWORDS:

• Wood
• hygroscopic properties
• programmable materials
• adaptability
• adaptive facades
• passive design

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are indebted to the funding provided by the Bartlett’s Fund for Science and Engineering Research Collaboration, in supporting the ‘Soft Adaptive Building Skins for Energy Efficient Architecture’ research project; a collaboration project between the American University in Cairo and Princeton University.