There are now numerous national and international researches that investigate technological strategies that are based and follow biological rather than mechanical principles. Nature suggests to the world of architectural design, technological strategies with minimal environmental impact, which are realized thanks to the innovation of sustainable architecture and to meteorosensitive architecture projects. These are obtained thanks to the application of smart building materials.
The meteorosensitive architecture and the innovative building materials already visible in the Hygroskin and Hygroscope Pavilions
In biological systems, reactive capacity is an intrinsic characteristic of the material itself. There are already examples in architecture that use design strategies that do not require mechanical or electronic commands or external energy supply to carry out their task. It is the same innovative building material used in the project, thanks to its properties, which adapts its shape to environmental change, without undergoing it but optimizing it according to the principle of resilience.
Sustainable architecture systems with new responsibly autonomous building materials
The sustainable architecture systems made with the new building materials are responsibly autonomous. They adapt to environmental changes by exploiting, for example, the hygroscopic properties of the material. Hygroscopicity refers to the ability of a substance to take moisture from the atmosphere when it is dry and release it into the atmosphere when it is damp,maintaining the amount of moisture in equilibrium with that of the surrounding environment.
A considerable amount of dynamic systems in nature change, being influenced by the climate
For example, plants have different systems to respond to environmental changes. One particularly promising way is hygroscopic actuation, as it allows for metabolically independent movement and thus provides an interesting model for autonomous, passive and materially embedded responsiveness, to be reproduced in construction with innovative smart building materials.
The skin of the building like the pine cone
As in nature with some types of plants and fruits, for example pine and pine cones, even in sustainable architecture projects the building envelope can be characterized by a skin, characterized by reactive openings to climatic variations.
The hygroscopic actuation of the surface of the external envelope of the building allows a unique environmental and territorial experience. Perception varies locally through the subtle and silent movement of meteorosensitive architectural skin. In the meterosensitive architecture, the envelope makes evident the ability of innovative materials to perceive, act and react to external environmental stresses.
Morphogenetic design experiments: Hygroskin and Hygrosope, the French meteorosensitive pavilions
They have both been made in France and meet the principles of biomimetic architecture. The pavilions are able to independently change their material characteristics. In fact, Wood is a hygroscopic material; it can adsorb and/or desorb water from the surrounding environment, tending to reach an equilibrium condition when the atmospheric relative humidity (RH) is stable. Wood has the ability to absorb water molecules from the surrounding air in dry environments and to release them if the air is damp.
The humidity outside the building activates the opening and closing of the architectural structure with which the building’s skin was constructed, which is made up of wooden elements that open and close in response to the surrounding climate changes, regulating the amount of humidity inside the building in relation to the external one.
The Hygroskin pavilion project was commissioned to the architect Professor Menges Achim of the Institute for Computational Design, University of Stuttgart who, with the collaboration of colleagues Steffen Reichert and Oliver David Krieg, created two meteorosensitive structures that simply exploit the natural properties of wood. The pavilion was commissioned for a permanent exhibition at the FRAC Center in Orleans.
The building envelope was made by overlapping a series of spruce wood panels on a steel structure, subdivided by 28 squares in which, in each of them, there is a circular hole that allows light to penetrate inside it. These openings are formed by a reticular structure and a series of thin layers of triangular section wood, for a total of 1100 sheets.
The millimeter precision with which these elements have been carved, thanks to the 3D laser printer, allows Hygroskin to react naturally to changing external weather conditions. The behavior of the cone scales is simulated: when it rains and the humidity increases, the openings close by folding. During sunny days, when the internal temperature increases, the thin sheets of wood contract, widening the openings.
The other project, the Hygroscope, pushes the results already obtained with Hygroskin even more forward with a more complex solution.
The Hygroscope pavilion is on permanent display at the Pompidou Center in Paris, where two identical copies have been created, inserted respectively into two glass cases. In one of the two, the climatic conditions of Paris are reproduced exactly. In the second, the microclimate of the museum is simulated, based on the humidity caused by the visitors. The biomimetic nature of the envelope means that the building is a real visual indicator of the different climatic conditions.
The skin of the Hygroscope pavilion is made up of 4000 elements in maple wood, each of which is unique in shape and size, manufactured digitally. The thin layers of wood of each opening expand or contract differently depending on the variations in humidity, the orientation of the fibers, the dimensions and the thickness, giving rise to ever-changing shapes that respond to changes in the climatic conditions, from the more subtle than the most obvious.
In this way it is possible to have thousands of extremely useful information for future developments in meteorosensitive and sustainable architecture projects, able to adapt more closely to the environmental context.