Project team: Achim Menges, Steffen Reichert, Boyan Mihaylov
Project Development, Design Development: Institute for Computational Design, University of Stuttgart; Prof. Achim Menges, Steffen Reichert, Nicola Burggraf, Tobias Schwinn with Claudio Calandri, Nicola Haberbosch, Oliver Krieg, Marielle Neuser, Viktoriya Nikolova, Paul Schmidt
Design Development, Scientific Development, Robotic Fabrication, Assembly: Transsolar Climate Engineering, Stuttgart; Thomas Auer, Daniel Pianka
Location: Paris, France
The Hygroscope explores a novel mode of responsive architecture based on the combination of material inherent behaviour and computational morphogenesis. The dimensional instability of wood in relation to moisture content is employed to construct a climate responsive architectural morphology. Suspended within a humidity controlled glass case the model opens and closes in response to climate changes with no need for any technical equipment or energy. Mere fluctuations in relative humidity trigger the silent changes of material-innate movement. The material structure itself is the machine.
The project was commissioned by the Centre Pompidou Paris for its permanent collection and will be first shown in the exhibition “Multiversités Créatives“ starting on 2nd of May 2012.
Climate-responsiveness in architecture is typically conceived as a technical function enabled by myriad mechanical and electronic sensing, actuating and regulating devices. In contrast to this superimposition of high-tech equipment on otherwise inert material, nature suggests a fundamentally different, no-tech strategy: In many biological systems the responsive capacity is quite literally ingrained in the material itself.
This project employs similar design strategies of physically programming a material system that neither requires any kind of mechanical or electronic control, nor the supply of external energy. Here material computes form in feedback with the environment.
The meteorosensitive morphology floats in a fully transparent glass case. Within the case the climate corresponds to an accelerated database of the relative humidity in Paris. In this way, the case functions less as a separation from the interior space of the Centre Pompidou, arguably one of the most stable climate zones in the world, but rather provides a virtual connection to the outside, showing the subtle variations in humidity levels that we hardly ever consciously perceive through the system’s silent movement. These cyclic changes are interspersed with spontaneous climate events triggered by threshold transitions within a second data set of visitor vapour emission.
The resultant autonomous, passive actuation of the surface provides for a unique convergence of environmental and spatial experience. The perception of the delicate locally varied and ever changing environmental dynamics is intensified through the subtle and silent movement of the meteorosensitive architectural morphology. The changing surface literally embodies the capacity to sense, actuate and react, all within the material itself.
The project is based on more than five years of design research on climate responsive architectural systems that do not require any sensory equipment, motor functions or even energy. Here, the responsive capacity is ingrained in the material’s hygroscopic behaviour and anisotropic characteristics. Anisotropy denotes the directional dependence of a material’s characteristics, in this case the different physical properties of wood in relation to grain directionality. Hygroscopicity refers to a substance’s ability to take in moisture from the atmosphere when dry and yield moisture to the atmosphere when wet, thereby maintaining a moisture content in equilibrium with the surrounding relative humidity.
In the process of adsorption and desorption of moisture the material changes physically, as water molecules become bonded to the material molecules. The increase or decrease of bound water changes the distance between the microfibrils in the wood cell tissue, resulting in both a change in strength due to interfibrillar bonding and a significant decrease in overall dimension. Given the right morphological articulation, this dimensional change can be employed to trigger the shape change of a responsive element.
This enables to employ simple wood, one of the oldest and most common construction materials, as a climate-responsive, natural composite that can be physically programmed to compute different shapes in response to changes in relative humidity.
The system responds to relative humidity changes within its microenvironment of the glass case. When the humidity level rises, the system changes its surface porosity to breathe and ventilate the moisture saturated air. The climate changes within the case directly influence the systems behaviour.
The Centre Pompidou building is emblematic for a controlled architectural division between interior and exterior climate. In fact, the building celebrates the very technology that maintains the stable interior climate as one of its key architectural features. Within this highly controlled volume of the Centre Pompidou the little glass case serves as a container that allows transferring the continuous unfolding of exterior climatic events to the interior of the building. In this way it suggests how an architecture based on the intrinsic behavioural capacity of a material mediates between interior and exterior climates rather than separating them.
The humidifier and dehumidifier technology enclosed within the case’s base regulates the climate driven by two datasets. One is the record of changing relative humidity levels of Paris. The acceleration of these daily climatic variations to hourly changes in combination with the systems surface response allows experiencing the subtle environmental differences and the heterogeneity of microclimatic conditions that usually escape our spatial perception. The second dataset affects the absolute humidity within the case. Based on the number of visitors a proportional amount of the humidity that they emit (approx. 100g per hour per person) will be spontaneously released triggering the unpredictable unfolding of local climatic events, causing nonlinear and complex behavioural response patterns of the system.
For this project the computational design research and the related development of the generative code is as important as the material system research. The way machine computation is used to generate the system is directly related to the way material computation is employed to enable the system’s responsiveness. The data for physically programming the behaviour of the system during the fabrication process corresponds with digitally programming the code that unfolds the systems morphology. Thus computation and materialisation are inherently and inseparably related.
The system consists of custom developed elements made from a combination of quarter-cut maple veneer and synthetic composites. More than 4000 geometrically unique elements are digitally fabricated and the complex substructure is robotically manufactured. The composite system elements can be programmed to materially compute different shapes within variable humidity response ranges by adjusting the following five parameters: [i] the fibre directionality, [ii] the layout of the natural and synthetic composite, [iii] the length-width-thickness ratio and [iv] geometry of the element and especially [v] the humidity control during the production process.
The computational design process is based on these system-intrinsic variables and system extrinsic environmental data. An algorithm iteratively scans various fields of environmental intensities within the simulated environment of the glass case and provides the input data for a custom scripted process of computational morphogenesis. Mimicking the dynamics of ontogenetic development a recursive algorithm derives the system through striated linear growth patterns cumulating in cellular arrangements in climatically instable regions.