The integration of BIPV Adaptive Flakes in the building envelope

The research presented within this paper deals with the design of an adaptive BIPV (Building Integrated PhotoVoltaic) façade system able to self-orientate the photovoltaic layer to improve the energy production. To reach this goal, thin film solar cells are coupled with a thin layer of hydromorphic material that responds to changes in environmental humidity by modifying its own curvature. The hydromorphic layer consists of two wooden slats assembled together and produced from different types of trunk cuts. The adaptive layer thus obtained can change its shape as a function of temperature and relative humidity outdoor conditions, thanks to the different expansion coefficients of the two materials. In the winter period, the flakes are designed to be almost vertical so that the solar cells can receive direct sunlight in a favourable way; in the summer season, instead, they naturally present high values of curvature, orienting the solar cells so as to maximize the production of photovoltaic energy. The paper, after outlining the main technological features of the system, illustrates the geometry optimization process and the results of the performed energy simulations. In addition, it shows how these BIPV flakes can be installed on a wood frame to create modular panels that can be used as façade cladding, sun-shading system and street furniture item (e.g. bus stop shelters).