The rapid growth of photovoltaic (PV) installed capacity has driven advancements in photovoltaic technology, such as integrating PV panels into building envelopes. Temperature increases are known to negatively impact PV panel performance. This study investigates and optimizes the design of air-based cooling systems for PV roofs using experimental and numerical analyses, leveraging free natural convection for cooling. Experimental measurements included air inlet/outlet, PV panel, and roof surface temperatures. The primary parameters examined in Computational Fluid Dynamics (CFD) for the numerical study were the heights and widths of the air channels between the panels and the rooftop, with heights ranging from 25 mm to 75 mm and widths varying from 200 mm to 400 mm. There are good agreements between the numerical results and experimental measurements after model validation. The results reveal significant temperature non-uniformity across the surface of the PV panels, with a maximum temperature difference of 16.50 °C. The shading effect of the PV panels resulted in an average reduction in roof surface temperature by 12.90 °C. Parametric studies showed that changes in height had a more pronounced effect on cooling than in width. The optimal design was identified with a channel size of 75 mm × 400 mm, resulting in the lowest average PV panel temperature of 65.21 °C and enhanced temperature uniformity, with maximum efficiency reaching 11.54%.

Solar energy is a world-recognized green and pollution-free energy source. Photovoltaic technology based on solar energy has become the focus of new energy development. On this basis, how to improve the energy efficiency of solar energy has become a research hotspot. In this study, the solution method was used, acety-lacetonate was used as the precursor, and the mixture of dodecyl mercaptan (DDT) and oleylamine (OLA) was used as the solvent to obtain CuInS₂ nanocrystals with wurtzite structure. Then, the dispersion of organic synthesized CuInS₂ nanocrystals was retained, and the organic macromolecules affecting electron transport in the nanocrystals were eliminated. This material was used for the counter electrode of dye-sensitized solar cells. While analyzing the photoelectric characteristics of the nanoelectronic material, the hardware of the photovoltaic solar cell prepared based on the material should be designed, including the selection of the main control unit, the design of the peripheral circuit, the design of the charging and discharging circuit, so as to realize the management of the photovoltaic solar cell. In the test, OLA had an impact on the crystal structure, size, and dispersion of CuInS₂ nanocrystals, thereby changing the photoelectric properties of the nanoelectronic materials, which were applied in photovoltaic panels for green buildings. The photoelectric conversion efficiency of CuInS₂ nanocrystals after phase exchange in the green build-photovoltaic system was much higher than that of CuInS₂ nanocrystals before phase exchange, and even higher than that of CuInS₂ nanocrystals calcined at high temperature before phase exchange in the green build-photovoltaic system.

This study investigates the external environmental temperature distribution of a small single-story BIPV building on a university campus in Jinan City, Shandong Province, China, under the most adverse summer high-temperature conditions. The temporal and spatial distribution characteristics and variation patterns of building external temperature are analyzed. The results indicated the following: (1) During summer high-temperature days, the peak temperature of the BIPV photovoltaic surface reached 52.4 °C, which is 17.4 °C higher than the ambient temperature. (2) External measurement points exhibited significant daytime heating (+2.86 °C) and nighttime cooling (average relative temperature increment of −1.52 °C). (3) Complex nonlinear temperature gradient variations existed within the 10–100 cm range from the surface, with localized heat accumulation occurring around 60 cm, where 77% of high-temperature days show temperature gradient anomalies. (4) Based on dimensionless analysis, a modified Richardson criterion for BIPV buildings is established: Ri < 0.3 represents building-geometry-dominated mechanisms, and Ri > 0.7 represents thermal-plume-dominated mechanisms. The critical values occur earlier than in classical theory. (5) Solar radiation and wind speed are key factors affecting temperature distribution, with more pronounced local heat accumulation under low-wind-speed conditions. This study provides scientific evidence for BIPV building performance optimization and environmental control.

To gain further insight into the thermal performance of a glass curtain wall with an enclosed rectangular cavity, a 2D mathematical model was established to analyze the characteristics of radiation and convective heat transfer in the glass curtain wall with an enclosed rectangular cavity, as well as to evaluate the effect of the glass curtain wall structure on thermal performance. The results showed that the total heat flux of the glass curtain wall with an enclosed rectangular cavity decreased at a decreasing rate with the increase in emissivity of glass. The total heat flux of the glass curtain wall with an enclosed rectangular cavity decreased with the increasing height of the enclosed rectangular cavity. At 15 mm thickness of the glass curtain wall, the total heat flux reached its minimum value and then increased with further thickeness of the enclosed rectangular cavity. In addition, the least square method was used to obtain the Nu correlation of argon with a relative deviation of less than 12% for better predicting the flow and heat transfer characteristics of argon in the glass curtain wall.

This study investigates the soil thermal imbalance of ground-source heat pump (GSHP) systems in residential buildings in cold regions and evaluates their economic and low-carbon performance. A case study is presented of a two-star green-certified residential building in Qingdao. The building exhibits a high heating load in winter, a low cooling load in summer, a long heating season, and large load fluctuations. To tackle these characteristics, a composite energy system combining a ground-source heat pump, a peak-shaving chiller, and a peak-shaving boiler is proposed. Three scenarios are designed, in which the ground-source heat pump covers 45%, 50%, and 52.6% of the winter peak heating load, respectively. These are compared with a conventional municipal heating scheme. Load simulation, techno-economic analysis, and carbon emission assessment are performed. The results show that the scheme in which the ground-source heat pump handles 50% of the peak heating load achieves the best overall performance. It reduces the soil thermal imbalance rate from 34.47% to 7.1% and obtains the lowest 10-year life-cycle cost. The annual carbon emission reaches 32.58 kgCO₂/(m²·a), representing a 33% reduction compared with municipal heating. Seasonal and diurnal optimized operation strategies are further proposed based on the optimal solution. The results provide theoretical and engineering guidance for the design and operation of low-carbon energy systems in green residential buildings in cold regions.