Hygrosensitive Kinetic Façade
The project “Hygrosensitive Kinetic Façade” investigates the architectural application of the hygrosensitivity of wood. The final design is a kinetic façade system installation made of a maple-spruce bilayer that passively responds to changes in relative humidity in the environment.
Hygroscopic behavior in wood has not been widely applied in architectural design. Therefore, initial research was conducted on this material behavior, including its effects on wood types and wood bilayer actuators. A humidity chamber was built to control the relative humidity, which fostered an exploration of the dimensional change of wood bilayers in relation to moisture condition. Experiments were conducted to better understand the wood’s hygroscopic behavior; these focused on aspect ratio, thickness ratio, geometry, and grain orientation.
The design process was a combination of a bottom-up material implementation and a top-down design proposal. Since wood is a natural material, its nonuniformity leads to an uneven dimensional change. As a result, the façade’s basic geometry was generated using only two major parameters—grain orientation and moisture content—to optimize certainty in the shape change. Computational simulation was performed on a dynamic shape to predict the curvature conditions. The Timoshenko Equation was adopted to simulate the curvature of bi-layer wood caused by relative humidity fluctuation in the environment. Changes in the width of the bilayer pieces were restricted to ensure that the final installation matched the simulation to the greatest extent possible. Hygroscopic bending formed the monoclastic bilayer pieces in this project. These were unrolled to return to their original shapes before being bent for fabrication.
This shape-shifting façade demonstrates the potential for new architectural applications of wood to achieve both aesthetic and functional results. The façade is environmentally friendly because it is made of wood, which is one of the most eco-friendly materials, and is a passive system actuated only by environmental factors that require no additional energy. Therefore, this kinetic façade system has the potential to be used broadly in future envelope design.
This project received the following honors: Award of Honor (The Society of American Registered Architects Student Design Awards), Award of Merit (SARA NY Design Awards), Silver Winner (IDA Design Awards), Silver Prize (Wood Change Award), Student Award Winning Architecture Projects (World Architecture Community Awards), and Honorable Mention (Fast Company’s Innovation by Design Awards).
Author and Image Credit
Mingyue Nan, Zhenfang Chen, Liwei Liu