Solar thermal venetian blind as synergetic and adaptive sun protection device in double skin façades

Solar thermal venetian blinds (STVB) offer a novel solution to reduce the energy demand of buildings with highly transparent façades. They can provide solar control functions like adaptive glare protection, control of solar heat gains and daylight. At the same time the STVB functions as solar thermal collector and can be used to preheat domestic hot water or as a source for heat pumps. STVB can be integrated into glass facades such as double skin and closed cavity façades and prevent overheating of the cavity by extracting excess heat. A test sample of a double skin façade element with integrated STVB was manufactured at Fraunhofer ISE. By employing heat pipes and a switchable thermal coupling for heat transfer from each slat to the header tube, all thermal connections within the STVB are dry connections. Outdoor calorimetric measurements of the façade element were conducted to evaluate solar thermal performance and solar heat gain control. Based on the measurement data a simulation model is currently being calibrated and validated.