Study of a BIPV Adaptive System: Combining Timber and Photovoltaic Technologies

The paper presents the first results of research that was partly conducted within the framework of European COST Action TU1403 – Adaptive Façades Network, on the development of an adaptive BIPV (Building Integrated Photovoltaic) solution able to change its curvature in relation to the external environmental conditions, orientating itself in order to optimise the energy production without the aid of any mechanical and electrical systems. After analysing the characteristics of the main adaptive materials that are currently used for such applications, the contribution outlines the main features of the proposed system, which consists of thin film solar cells coupled with a thin layer of hygromorphic material, manufactured from two wooden slats joined together and produced from different types of wood and trunk cuts. The hygromorphic layer thus obtained can change its shape as a function of temperature and relative humidity of outdoor conditions, thanks to the different expansion coefficients of the two wooden slats. To evaluate the performance of the component, three shape configurations for the adaptive strips have been assumed. For each hypothesis, the lamellae have been modelled using the Rhinoceros 5 Software, according to the curvatures taken during the different months of the year. The Rhino models have been imported into Autodesk Ecotect Analysis to calculate the incident solar radiation and to study the self-shadowing effect in the various configurations (in relation to the climatic conditions of the city of Milan). The paper outlines the system and PV energy production optimisation process, as well as possible applications in the field of façade design.