This study investigates the aerodynamic behavior of roof structures under wind-induced forces, focusing on buildings equipped with photovoltaic panels. Experimental data were obtained through wind tunnel testing of three 1:100 scale models, each representing a distinct roof geometry: gabled, hipped, and multi-pitched. Measurements of dynamic pressure and pressure coefficients were conducted for various wind incidence angles, ranging from 0° to ±150°. The results highlight the impact of roof geometry and PV panel placement on the pressure distribution, with notable variations due to flow separation and vortex formation around the panels. Gabled roofs exhibited pronounced pressure gradients, while hipped roofs showed more uniform distributions. Multi-pitched roofs demonstrated the most complex aerodynamic behavior due to their variable slopes. These findings enhance the understanding of wind-structure interactions for buildings with roof photovoltaic panels, contributing to the development of more resilient and energy-efficient structures. The research supports sustainable construction practices by improving wind load predictions and informing design decisions that promote the safe integration of renewable energy systems into the built environment.

Courtrooms are tall, densely occupied rooms in which cold glazing, radiator plumes and stratification shape winter comfort - effects that single-zone energy calculations miss. We combined infrared thermography with steady three-dimensional CFD simulations (OpenFOAM, Boussinesq approximation, k-epsilon model, cross-checked with Ansys Fluent) to assess how window replacement and external wall insulation change the heating demand and the thermal comfort in the occupied zone of three courtrooms in Iasi, Romania, at the design outdoor temperature of -18 C. Thermography identified the glazing as the weakest element of the recent building envelope. In all rooms and scenarios the radiators placed under the windows prevented downdraught in the occupied zone: the mean draught rate was 2-7%, the head-ankle temperature difference 0.9-1.8 K (an upper estimate) and the mean PMV between -0.10 and +0.02 (category A of ISO 7730). With radiators sized for the design transmission loss, the occupied-zone air reached 23-24 C, close to the values measured in winter 2025, which points to an oversupply of heat in milder weather. Window replacement cut the transmission loss by 13-21%, and its combination with wall insulation by 39-75%. After retrofit, the ventilation required by EN 16798-1 becomes the largest heat loss, so demand-controlled ventilation with enthalpy recovery should accompany the envelope measures.

This study presents an experimental investigation on the electrical performance, durability, and sustainability of different types of photovoltaic panels subjected to controlled climatic conditions and simulated solar radiation. Four photovoltaic technologies were analyzed, including monocrystalline, polycrystalline, and two semi-flexible panels, to evaluate their behavior under thermal stress. The experimental methodology consisted of repeated freeze–thaw cycles conducted in a double climatic chamber, with temperatures varying between −18 °C and +5 °C. Each panel was subjected to up to 500 cycles designed to reproduce repeated freeze–thaw environmental conditions representative of moderate cold-climate operation. At predefined intervals, the electrical characteristics of the panels were assessed using a solar radiation simulator based on high-pressure mercury vapor lamps, ensuring controlled and repeatable irradiation conditions. The results indicate that all tested panels exhibited relatively stable open-circuit voltage and output current values throughout the investigated thermal cycling interval, with only minor fluctuations observed during the experimental measurements. No visible macroscopic structural degradation and no major variations in the monitored electrical parameters were identified during the investigated testing conditions. Semi-flexible panels demonstrated comparable behavior to rigid panels, highlighting their potential for applications requiring mechanical adaptability. From a sustainability perspective, the observed durability and performance stability contribute to extending the operational lifetime of photovoltaic systems, reducing maintenance needs and material replacement rates. The findings provide comparative experimental observations regarding the evolution of selected electrical parameters under repeated moderate freeze–thaw exposure conditions.