Abstract
The use of passive solutions for building envelopes represents an important step toward the achievement of more efficient and zero-energy building targets. Trombe walls are an interesting and viable option for the reduction of building energy requirements for heating, especially in cold climates. This study presents the experimental analysis of an innovative Trombe wall configuration, named a thermo-diode Trombe wall, which was specifically designed to improve the energy efficiency by providing a proper level of insulation for the building envelope. Such a design is essential in cold climates to limit the thermal losses whilst increasing solar heat gains to the heated spaces. An experimental campaign was conducted from December to March that involved monitoring the external climatic conditions and the main thermal parameters to assess the thermal performance of the proposed solution. The results demonstrated that in the presence of solar radiation, the thermo-diode Trombe wall was able to generate significant natural convection inside the air cavity, with temperatures higher than 35 °C in the upper section, by providing consistent heat gains for the indoor environment, even on cold days and for hours after the end of the daylight. The efficiency, relative to the incident solar radiation, reached 15.3% during a well-insolated winter day.