Water, Wood and Temperature: Hygroscopy at its best

Our research “Programmable matter: A multi-physics modeling approach for low-tech architectural adaptive systems using hygroscopic properties of wood,” Computer-Aided Design, https://doi.org/10.1016/j.ca has just been published. We are very happy to share our brand new paper on this topic. Get a copy free here https://authors.elsevier.com/a/1XhO22O2yECEV

When the relative humidity in the air increases, wood increases in volume as the water molecules become suspended between the wood cellulose fiber molecules.  In wooden laminates made of different wood species, grain orientations or thicknesses, this phenomenon can cause  fascinating shape shifting forms as the different wood layers start interacting.

The goal of final project of  course CEE546 “Form Finding of Structural Surfaces”  was to tailor the hygroscopic behavior of wood for the design and construction of a shape-shifting façade panel. Such a panel could be incorporated in an adaptive building skin.The purpose of adaptive building skins is to actively moderate the influence of weather conditions on the building’s interior environment. Current adaptive skins rely on rigid body motions, complex hinges and actuation devices. These attributes are obstacles to their broader adoption in low-carbon buildings. This project explored these challenges and solutions. The core idea of hyrgoscopic adaptive skins is that they exploit the inherent swelling and shrinking wood properties to change their shape and respond to external weather conditions of changing humidity and temperature.

A number of  projects, physically and numerically developed and prototyped by teams of graduate engineers and architects in the Spring of 2017, are presented here.

Project 1: The aim of the project was to understand the behavior of a tri-layer adaptive wood facade subject to different configurations of the active and resistive layers. We performed both numerical and physical experiments to achieve the same and the results from both were compared for validation. Understanding the behavior in different configurations will help us use the optimum one for specific purposes. (Ryan Roark, Vivek Kumar, Emma Bonintende and Andrew Percival)



Project 2: The motivation of “The Wave” was to create a shape-shifting hygroscopic panel without the use of outside actuators that would be able to respond naturally to weather events, providing appropriate ventilation and lighting while presenting the ebb and flow of an ocean wave. The goal of the sliding panel was to create waving openings during sunny dry weather but to flatten closed during rainy or humid days (Peter Wang,  Laura Salazar, Jedy Lau and Myles McCaulay)




Project 3: The goal of our project was to create a shape shifting façade which opens and closes as if it were a flower. Given diamond shaped flower units, the types of wood, and the thickness of both the active and passive layers, we optimized the height of the triangular petals and the grain orientations of both the active and passive layers of façade to ensure the flower petals not only meet in the center but also maintain reasonable stress levels. ( Ivy Feng, Doris Avit, Andrew Rock)




Project 4: The facade system is conceived as a temperature moderating outer skin that provides shade and ventilation for a building or public space in a hot, arid climate. Utilizing the shape-shifting properties of wood veneer, the facade panels curve when exposed to moisture and relax when dried. The project reconsiders the dynamic facade as a system that functions through an inherent material intelligence rather than a mechanized assembly. The project further considers the possibility of utilizing vegetation or man-made water features in concert with with diurnal temperature changes to provide the necessary humidity to allow the facade to open and close through the course of a day and adapt seasonally to variations in weather and solar gain. (Veronica Boyce, John Cooper and Devin Dobrowolski)

Wood Sample Matrix



Project 5: We used this project to explore the effects geometry and grain orientation had on the hygroscopic properties of wood. We tested different ratios of triangle shapes and either parallel or perpendicular grain orientation between two layers of wood and compared the stresses and deformed shapes to optimize the shape. (Annie Levine, Sean Rucewicz)



This project was made possible through the William Pierson Field Fund and the  Bartlett Funding  with the collaboration of Prof. Gabriele and Luigi Olivieri (Roma Tre University, Italy) and Prof. Abdelmohsen and Rana Ahmed Bahaa (American University of Cairo).

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