The negative effect of the operating temperature on the functioning of photovoltaic panels has become a significant issue in the actual energetic context and has been studied intensively during the last decade. The very high operating temperatures of the photovoltaic panels, even for lower levels of solar radiation, determine a drop in the open-circuit voltage, with consequences over the electrical power generated and PV-conversion efficiency. The temperature effect over the efficiency of monocrystalline and polycrystalline photovoltaic panels by using a double-climatic chamber and a solar simulation device was studied experimentally for two photovoltaic panels, one monocrystalline and another polycrystalline, with the same nominal power of 30 Wp. The double-climatic chamber used is composed of two separate rooms, a cold and a hot one, while the PV panel is placed as a barrier between them. The study is focused on establishing the effect of raising the temperature of PV panels over electrical parameters: voltage, current, and power produced and for efficiency and fill factor to promote sustainable energy consumption. The findings highlight the positive impact of cooling on enhancing system efficiency, with the primary focus on quantifying its overall performance. The operating temperature is controlled by the flow of air on the backside of the PV panel inside the cold room. The level of radiation studied corresponds to a vertical integration of PV panels in building façades. The coefficient of the mean variation of the efficiency with the photovoltaic panels’ temperature was −0.52%/°C; for voltage, −0.48%/°C, and for current, +0.10%/°C.

The effect of the use of TiO₂ nanoparticles in the production of cementitious composites, worldwide already known, represents an area of interest for the development of materials with self-cleaning capacity; antimicrobial, antibacterial, antifungal properties; and to contribute to the reduction of environmental pollution. This paper aims to analyze the influence that TiO₂ nanoparticles have on the cementitious matrix regarding hydrophilicity, this being one of the two main parameters of the self-cleaning mechanism. Experimental tests, conducted by using the indirect method of measuring the surface water absorption, indicated that an addition of 3%-6% (relative to the amount of cement) of TiO₂ nanoparticles is effective in terms of increasing the surface hydrophilicity of the cementitious composites. An excess of TiO₂ nanoparticles in the composite matrix (10% TiO₂ nanoparticles relative to the amount of cement) not only does not improve surface performance in terms of hydrophilicity, but also reduces them. However, in practice on a case-by-case basis, an analysis is required regarding the optimal amount of nanoparticles used as an addition in the mix-design of the cementitious materials that are intended to induce the quality of self-cleaning process, depending on the intended use, climate, degree and duration of sunlight, and so on.

The negative effect of the operating temperature over the functioning of photovoltaic panels has become a significant issue in actual energetic context, being studied intensively during last decade. The very high operating temperatures of the photovoltaic panels, even for lower levels of solar radiation, determines a drop of the open circuit voltage, with consequences over the electrical power generated and photovoltaic conversion efficiency. The aim of the study is to investigate experimentally the temperature effect over the efficiency of monocrystalline and polycrystalline photovoltaic panels by using a double climatic chamber and a solar simulation device. Within the experimental program were analyzed two photovoltaic panels, one monocrystalline and another polycrystalline, with the same nominal power of 30 Wp. The double climatic chamber used is composed of two separate rooms, the cold and hot one, while the PV panel is placed as a barrier between them. The study is focused on establishing the effect of raising the temperature of PV panel over electrical parameters: voltage, current and power produced and for efficiency and fill factor. The operating temperature is controlled by the flowing of air on the backside of the PV panel inside the cold room. The simulation of solar radiation was performed by using an equipment compatible with the dimensions and characteristics of the climatic chamber. The level of radiation studied corresponds to a vertical integration of PV panels in building facades. The coefficient of the mean variation of the efficiency with photovoltaic panels’ temperature was -0.52 %/°C, for voltage -0.48 %/°C and for current +0.10 %/°C.

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.