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ISBN 978-3-8439-4930-9

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978-3-8439-4930-9, Reihe Mikrosystemtechnik

Carmen Juliane Eger
Hygromorphic Polymeric Actuators for Smart Building Façades Inspired by Pine Cones

202 Seiten, Dissertation Albert-Ludwigs-Universität Freiburg im Breisgau (2021), Softcover, B5

Zusammenfassung / Abstract

One of the biggest challenges that society currently faces is climate change. As such, the Paris Agreement made lowering carbon dioxide emissions a key objective for improving the environment. The European Union uses 50% of the annual energy consumption to heat and cool buildings. Adaptive facades are a possible solution for increasing the energy-efficiency of buildings, thus reducing their carbon dioxide emissions. The existing adaptive facades, however, are technically complex, have a high maintenance need and need an external energy supply. The aim of this work was to develop a passive and hygroscopic actuator to be used as an executive component in an energy-efficient adaptive facade. Due to the passive water uptake and release and subsequent closing and opening of the cone, Pinus Wallichiana was the biological role model for the development of the hygroscopic actuator. The key functions of the bending mechanism of P. Wallichiana were identified based on hydration measurements and the study of the mechanical properties during swelling. It could be shown, that the structure and the function are more complex than previously described in literature. Additionally, a novel model of how the water is taken up in the pine cone was proposed. In this thesis the development of the hygroscopic actuators, made from hydrogel and polyester, is described. Furthermore, the complex interplay of physical and chemical properties that influence the bending motion is described. In order to be used as executive component in an energy-efficient adaptive facade, the actuator has to fulfill relevant properties, which are also investigated and discussed in this thesis. The bending motion of the resulting actuator is adjustable, reproducible, durable and the actuators are strong enough to support panels with five times their own weight. By combining the actuators with a panel and attaching them to a model house, a model with possible design proposal for the adaptive facade was made.