The concept of integrating PV panels into traditional ETICS facades has been developing for several years. Problems concerning the options for passively controlling the temperatures of PV panels with PCM and directing excess moisture out of the wall via diffusion channels have been previously studied theoretically. During this study, real wall-scale experiments were conducted to test the thermal and hygrothermal performance of the wall system in an extreme climatic environment, as well as in a real outdoor environment in Tallinn, Estonia. Finally, a simulation model was calibrated according to the measured data. It was found that in case of test walls with diffusion channels, it was possible to keep the moisture content of PCM mortar under 0.11 m³/m³. Excess water drained out via channels leading to the external environment. Without diffusion channels, the moisture content rose as high as 0.18 m³/m³. Both the experiments and hygrothermal modelling showed that the high moisture content of PCM mortar, caused by water leakage, dropped to 0.08 m³/m³ over 10 solar cycles as moisture escaped via the diffusion channels. PCM mortar with a moisture content of 0.08 m³/m³ endured extreme rain and freeze-thaw cycles without visual damage, and PV panels retained their electrical production capabilities.

This study assesses the hygrothermal performance of the Photovoltaic External Thermal Insulation Composite System (PV ETICS), using a thick layer of mortar with Phase Change Material (PCM) granules as a passive heat sink. The experimental scenario involved the wall system exposure to real outdoor climate conditions during a 20-month long measurement period. Measured data were compared with results from the hygrothermal modelling. The findings reveal that with carefully designed diffusion channels the PV ETICS demonstrated no accumulation of moisture behind the vapour-tight PV panel. Long term hygrothermal modelling for PCM mortar moisture content with a previously calibrated model predicted stable moisture content around 0.03 m ³ /m ³ , significantly lower than the moisture content during first 2 years. Relative humidity behind the PV panel falls into the hygroscopic range on the second spring after the construction. The annual maximum temperatures for PCM mortar during two summers were 69°C, occurring in mid-August. Risk analysis was conducted with historic climate data to understand, whether higher PCM temperatures could be reached in the same climate for different years. Overall, the wall system showed no signs of extensive moisture damage during the testing period, but slight discolouring of the PCM mortar was recorded. This study contributes valuable insights into the practical viability of PV ETICS with PCM mortar, reaffirming its potential for application on larger scale on real building facades.

External Thermal Insulation Composite System (ETICS) facades are widespread and cost-effective building solutions in many climates. However, they are frequently found to deteriorate prematurely. In addition to other possible defects, several buildings were found with horizontal cracks on the facade between every floor level. Because of the fire safety requirements of multi-storey buildings, EPS insulation has been divided by mineral wool fire breaks at each floor level. The service life of the system usually ends up with horizontal cracks appearing at the lower level of the wool belt. This study aimed to determine the damage mechanism. One deteriorated facade was opened to explore possible construction technology errors and specimen were analysed in the laboratory. Temperature and RH were measured in situ inside the walls at different positions. It turned out that built in moisture of concrete was still drying out after three and a half years. Moisture content of concrete was found to be between 0.046 to 0.063 m³/m³ behind EPS insulation and 0.047 to 0.074 m³/m³ behind MW insulation - slightly higher than hygrothemal model was predicting. A possible solution was proposed to alleviate the similar problem in the future with application of waterproofing membrane behind mineral wool.

The paper describes the conceptualisation of a new façade-integrated photovoltaic system. The paper provides an overview of existing building-integrated photovoltaic solutions as a reference point for developing a new system. Then it discusses technical constraints, including durability, maintenance, and service life, to guide the selection of system components such as boards, frames, PV panels, cables, connectors, and binders. The hygrothermal performance was assessed based on two essential criteria influencing the operation and durability of the PV system: the risk of overheating and the risk of condensation. These analyses require laboratory measurements of material properties, and the obtained results will enable an assessment of electrical efficiency under real-world operating conditions. Additionally, factors such as aesthetics, adaptability, and cost-effectiveness will determine the ultimate concept of this technology for further development. The authors propose a method for developing the ActiVer system for smart building envelopes. In this study, we developed the initial concept of system construction, consisting of two main boards: i) the first, which is the back side, permanently connected with the construction of the external wall, and ii) the second, which consists of single panels easily replaceable for maintenance. Both boards are made from the natural, lightweight and environmentally friendly perlite-based raw material. The unique technical features include being largely prefabricated, self-supporting, compatible with different external wall constructions, and easy to maintain. Moreover, based on the main project assumptions, the system is characterised by guaranteed hygrothermal performance, a low carbon footprint, and reusability. The proposed PV system is based on the custom-made, semi-flexible PV modules equipped with monocrystalline back-contact cells. All technical details in a graphical form, including electrical connections and mechanical joints of the boards, are also presented. The research and development study is conducted in cooperation with the industrial partner.