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The secondary solar heat gain, defined as the heat flows from glazing to indoor environment through longwave radiation and convection, grows with the increasing of glazing absorption. With the rapid development and application of spectrally selective glazing, the secondary solar heat gain becomes the main way of glazing heat transfer and biggest proportion, and indicates it should not be simplified calculated conventionally. Therefore, a dynamic secondary solar heat gain model is developed with electrochromic glazing system in this study, taking into account with three key aspects, namely, optical model, heat transfer model, and outdoor radiation spectrum. Compared with the traditional K-Sc model, this new model is verified by on-site experimental measurements with dynamic outdoor spectrum and temperature. The verification results show that the root mean square errors of the interior and exterior glass surface temperature are 3.25 °C and 3.33 °C, respectively, and the relative error is less than 10.37%. The root mean square error of the secondary heat gain is 13.15 W/m 2 , and the dynamic maximum relative error is only 13.2%. The simulated and measured results have a good agreement. In addition, the new model is further extended to reveal the variation characteristics of secondary solar heat gain under different application conditions (including orientations, locations, EC film thicknesses and weather conditions). In summary, based on the outdoor spectrum and window spectral characteristics, the new model can accurately calculate the increasing secondary solar heat gain in real time, caused by spectrally selective windows, and will provide a computational basis for the evaluation and development of spectrally selective glazing materials.

The energy consumption requirement of high-rise buildings necessitates effective innovations in architectural designs. The aim is to revolutionise high-rise buildings’ thermal features and energy efficiency. This paper combines quantitative analyses through improved thermal simulations and qualitative information from surveys of stakeholders, including architects, engineers, and urban planners. Key performance indicators such as U-values, R-values, HVAC efficiency, Solar Heat Gain Coefficient (SHGC), and Energy Use Intensity (EUI) are examined in detail to assess the thermal and energy performance of contemporary façade systems. Energy-efficient building design is paramount in this time of unprecedented urban development and escalating global temperatures. However, a gap exists in understanding how these practices can be adapted and integrated effectively into modern architecture. The findings show that high-rises with optimized pattern curtain wall façades reveal considerable savings in energy usage, particularly in cooling loads, which enhances indoor thermal comfort and reduces environmental effects. Actionable recommendations are provided for architects, urbanists, and policymakers, including the designs of region-specific façade constructions, their connection with renewable energy, and compliance with high energy performance standards. All these strategies help to improve the operational efficiency, environmental sustainability, and stability of built environments in growing, developed urban areas.

The work emphasizes on energy saving in multi-layered glasses. Appropriate multi-layer designing was envisaged with various possibility and measured the transmittance of light in UV-Vis-NIR range. Various glasses were selected to study their transmittance for their specific advantages among each other for designing the multi-layer.Visible region showing higher transmittance revealing that these glasses allows more light in this range. While in the IR region these glasses show less transmittance revealing that these glasses doesn’t transmit much heat, this being the interest of study to stack the glasses for multi-layered glass with smart film then subjected to study their optical behavior and understood their energy saving phenomenon from window 6 program to obtain Solar Heat Gain Coefficient (SHGC) and Light to Solar Gain (LSG) data. Such multi-layered glasses can be used as a database in industrial plants.

In several developing countries, energy performance rating programs are currently in progress. Complex fenestration systems (CFS) are building components that play a key role in reducing energy consumption. The development and testing of equipment is central for beginning the energy efficiency rating process of complex glazing systems in these countries. This paper validates the use of a low-cost hot-cold box calorimeter for measurement of the solar heat gain coefficient (SGHC) and overall heat transfer coefficient ( U -value) of interior shading systems. This work aims to determine the energy performance of three types of often employed shading systems: solar control films, interior horizontal venetian blinds, and indoor drapery curtains. Results show that the energy performance of solar shading devices studied depends on both their morphological and optical properties. The shading systems analyzed present similar U -values, where technological features are represented by the thickness and the thermal conductivity of the material. SHGC is mainly defined by the transmittance and, to a lesser extent, the absorptance of the systems, which differ significantly according to the analyzed shading device. The three types of curtains analyzed demonstrate an SHGC dependent on the fabrics openness factor: jacquard curtains (openness factor 0.05) present a SHGC of 0.7, whereas organza curtains (openness factor 0.45) have a SHGC of 0.82. The SHGC of the venetian blinds analyzed varies on average 36% according to the slat tilt (0°–45°). The solar control films examined modify their solar gain according to their spectral selectivity.

The sector of transportation accounts for about one third of the total energy consumption in Switzerland. A monitoring campaign of the energy consumption of a regional train revealed the critical energy-consuming systems. Heating, cooling and ventilation were identified as major consumers. Windows are a source of non-controlled heat transfer. In summer, it may result in overheating leading to larger cooling loads while in winter, it is an important source of thermal losses. Selective double glazing and solar protection coatings can reduce these effects. Angular-dependent optical properties of a selective double glazing have been measured, and the solar heat gain coefficient (g value) was determined. An estimation of the solar gains received by a panoramic waggon was performed using the monitored solar irradiation and the measured properties of the glazing. These data were compared to the heating and cooling energy consumption monitored in this waggon. Solar gains were found to be in the same order of magnitude that the heating energy during some sunny days. They were also compared to the estimated thermal losses through the glazing and the entire envelope. These results show that the solar gains play a non-negligible role in the energy balance of the waggon. Furthermore, thermal simulations were performed to evaluate the solar gains in different conditions. It showed that 7 to 13% of energy can be saved using the glazing adapted to the climatic conditions. In addition, improving the thermal insulation of the train envelope or equipping the train with an efficient heat recovery system can lead to significant energy savings.

Cooling in buildings is vital to human well-being but inevitability consumes significant energy, adding pressure on achieving carbon neutrality. Thermally superinsulating aerogels are promising to isolate the heat for more energy-efficient cooling. However, most aerogels tend to absorb the sunlight for unwanted solar heat gain, and it is challenging to scale up the aerogel fabrication while maintaining consistent properties. Herein, we develop a thermally insulating, solar-reflective anisotropic cooling aerogel panel containing in-plane aligned pores with engineered pore walls using boron nitride nanosheets by an additive freeze-casting technique. The additive freeze-casting offers highly controllable and cumulative freezing dynamics for fabricating decimeter-scale aerogel panels with consistent in-plane pore alignments. The unique anisotropic thermo-optical properties of the nanosheets combined with in-plane pore channels enable the anisotropic cooling aerogel to deliver an ultralow out-of-plane thermal conductivity of 16.9 mW m −1 K −1 and a high solar reflectance of 97%. The excellent dual functionalities allow the anisotropic cooling aerogel to minimize both parasitic and solar heat gains when used as cooling panels under direct sunlight, achieving an up to 7 °C lower interior temperature than commercial silica aerogels. This work offers a new paradigm for the bottom-up fabrication of scalable anisotropic aerogels towards practical energy-efficient cooling applications. Scaling up anisotropic freeze-casting processes can be challenging due to the temperature gradient farther from the cold source. Here, authors report an additive freeze-casting technique able to produce large-scale aerogel panels and demonstrate it towards practical passive cooling applications.

In 2023 the NOAA Daily Optimum Interpolation Sea Surface Temperature in the Atlantic set new records, peaking above 24. 3°C for the full basin 30°S–60°N and above 25. 3°C for the North Atlantic 0–60°N, both for the first time during the satellite era. Proposed mechanisms include anomalous radiative and thermodynamic surface fluxes, horizontal transport, changing mixed layer thickness and basal entrainment rates. To test these ideas the heat budget of the ocean mixed layer was examined in a numerical simulation. The results show that the anomalous SSTs in the North Atlantic during the summer of 2023 were caused by increased shortwave warming and reduced thermodynamic cooling. In contrast, ocean mean and eddy heat transport convergence and heat exchanges along the mixed layer base dominate only regionally. A second contributor to the record SSTs was the preconditioning of mixed layer temperature following a series of anomalously warm years. Plain Language Summary 2023 SSTs hit record high levels in the North Atlantic, causing widespread environmental damage. This study uses a simulation of the mixed layer heat budget in the past few years to identify two main causes of the record high 2023 SSTs and closely related mixed layer temperatures. The first was an increase of atmospheric heating due to a combination of higher‐than‐normal solar heat gain and lower‐than‐normal evaporative and sensible heat loss. The second was preconditioning of the spring 2023 mixed layer temperature following a series of anomalously warm years. Key Points The North Atlantic had record high sea surface temperatures (SSTs) and mixed layer temperatures in summer 2023 Extreme SSTs and mixed layer temperatures were caused by atmospheric heat flux Evaporative heat loss was abnormally low due to weak Northeast trade winds

TS 825 Thermal Insulation Requirements in Buildings, the obligatory standard, is still in effect, and is used to calculate the heating energy requirements of buildings in Turkey. The total solar heat gain through windows is calculated using the solar radiation table given in Appendix-C of TS 825. Although Turkey is divided into four different degree day regions according to this standard, Appendix-C offers the same solar radiation data for all regions. This study aimed to investigate the appropriateness of the Appendix-C table for the different degree day regions. The hourly solar radiation on the vertical surfaces of a building envelope was calculated for 16 selected cities. Long-term sunshine duration data for each location were obtained from the Turkish State Meteorological Service. It is demonstrated that the solar radiation table given in Appendix-C of TS 825 is not appropriate for the four degree day regions. The calculated solar radiation values of the cities are considerably different from the table values, with the ratios varying between 3.03% and 69.15% for horizontal surfaces, 0.171% and 53.29% for south, 0.25% and 22.15% for north and 0.60% and 40.42% for east and west oriented surfaces.

Solar radiation heat flux is a critical factor in human thermal comfort. Radiance software is the most accurate method for determining the distribution of direct and diffuse solar radiation in a room over time. Nonetheless, the validation of numerical models using real-world data is still outstanding, especially for replicating transient environmental conditions, such as changing cloud cover, surface reflectivity, and human posture. This study aimed to present a method for determining the intensity and distribution of solar radiation entering a room and falling on specific parts of the human body, which can be used as input to a human thermal comfort model. The method is demonstrated using a real office room located at the Empa in St. Gallen with geometry imported to Radiance via the Ladybug Tool, together with the human geometry for simulation. The validation of this numerical model was conducted based on measurements obtained using an instrumented human shape manikin and actual weather data. The study confirmed the accuracy of the simulation model in predicting solar radiation exposure of the human body. The results highlighted the significant impact of seasonal variations, room positioning, and furniture on solar heat gain, emphasizing the importance of workspace design in ensuring thermal comfort.

The estimation of the HTC heat transfer coefficient in real occupancy conditions has a great operational advantage contrary to the measurement in unoccupied conditions, which requires specific measurement protocols. Nevertheless, it presents additional constraints because the gains due to weather conditions and occupancy are poorly controlled. The objective of this work is therefore to quantify the impact of these different gains. A numerical test bench is set up to study the impact of the solar and internal gains by varying different parameters, such as the typology of the building, the meteorological conditions, the scenarios of occupancy. These numerical tests allow to estimate the HTC of a building by calibrating a numerical model from a virtual dataset generated by a detailed model with known and controlled meteorological conditions and usage conditions. They make it possible to determine the share of solar heat gain and internal heat gain in the energy balance of the building and their impact on the estimation of the HTC according to the studied configurations.