Search Results (28)

Growing demand for sustainable agricultural solutions has driven innovations in greenhouse design, particularly in urban areas. This study evaluated the relationship between transparent envelope thermal properties and greenhouse energy loads through regression analysis using DesignBuilder simulations. The thermal performance of the envelope was designated as independent variables to quantify its impact on heating and cooling loads. Based on this analysis, a rotatable low-emissivity (low-E) coating envelope system optimized for temperate climate zones was proposed. This system allows seasonal adjustment of coating orientation to enhance energy efficiency. Compared to traditional materials, this approach achieved up to 16% energy savings without compromising visible light transmittance, essential for crop growth. While double-glazed low-E glass demonstrated the highest energy reduction (22%), it reduced visible light transmittance by 20%, potentially affecting crop productivity. In contrast, the proposed system maintained high visible light transmittance while achieving significant energy efficiency, balancing energy performance and light environment requirements. Additionally, integrating the greenhouse with building structures resulted in a 31.91% reduction in building energy consumption through improved insulation. These findings highlight the potential of adaptable greenhouse envelopes to improve energy performance and support urban sustainability. Full article

This paper concerns measurements and CFD simulations of vacuum-insulated glazing (VIG), which consists of two glass panes separated by a narrow gap from which air has been removed. Distancers, e.g., in the form of small balls, are inserted into this gap every few centimeters to prevent the glass from deflecting. In the first part, simulations of two-pane VIG thermal transmittance with the Ansys Fluent program are described, resulting in thermal transmittance of VIG without the network of distancers equal to 2.18 W/(m²K) and with the distancers equal to 2.29 W/(m²K). The influence of the supports on the thermal transmittance of VIG is also determined. The CFD results show that the supporting balls increase the two-pane VIG thermal transmittance by about 0.15% with respect to the glazing without the distancers. Then, VIG is analyzed both numerically and tested in two measurement stands. Firstly, the tests are performed in a guarded hot-plate apparatus, according to the EN ISO 8302 standard. The two-pane glazing with one low-emissivity coating has a measured thermal transmittance equal to 1.75 W/(m²K). Other measurements were undertaken in the calorimetric chamber equipped with the hot-box apparatus. The results of the numerical assessment are then compared to the measurements of the existing three-pane vacuum-insulated glazing with two low-emissivity coatings, the same as simulated. The procedure follows the EN ISO 8990 standard. Measurement results of 1.10 W/(m²K) are compared to the simulation results of VIG thermal transmittance equal to 1.09 W/(m²K). A satisfactory agreement is reached. Additionally, this paper considers a new correction coefficient to thermal transmittance according to standard EN 673 in order to achieve a proper calculation of vacuum-insulated glazing in the center-of-glass region. The authors propose to use an adjustment coefficient of 1.05 when calculating the thermal transmittance of vacuum-insulated glazing without taking into account convection in the vacuum space and the thermal influence of distancers. Full article

This study examined the optical–thermal performance and energy efficiency of electrochromic (EC) glazing in residential buildings situated in regions characterized by hot summers and warm winters. Traditional glazing systems, such as double-layer (DL) and low-emissivity (LE) glazing, often face challenges in achieving an optimal balance between indoor lighting, glare control, and heat regulation. Using EnergyPlus simulations for a typical residential building, this research evaluated the performance of EC glazing under four control strategies, considering seasonal variations (summer and winter), building orientations, and energy demands for cooling, heating, and lighting. The results indicate that EC glazing dynamically adjusts the solar transmittance from 0.320 under low solar radiation to 0.012 at high levels, significantly reducing the glare and convection heat gains. The transmitted radiation heat gain for EC glazing is remarkably only 23.7 J·m⁻², compared to 736.8 J·m⁻² for DL glazing. Furthermore, EC glazing achieves a total energy consumption of 189.52 MJ·m², representing a significant 33.0% reduction compared to DL glazing. These findings underscore the potential of EC glazing to improve both the energy efficiency and visual comfort in residential settings. This study highlights the importance of optimizing control strategies, particularly in response to seasonal and directional variations, offering valuable insights for sustainable building design in climates with diverse thermal requirements. Full article

The utilization of heat-shielding glazing technologies can efficiently promote carbon emission reductions and energy savings by decreasing solar irradiation into buildings. Although a variety of glazing technologies have been created for solar glazing, either the heat-shielding performance is low, the thermal stability is poor, or the cost is high. Here, we report a thermally stable heat-shielding coated glass for solar glazing in a simple way via direct calcination of Ce and Sb co-doped SnO₂ nanoparticles with polysilazane (PSZ) coatings in air. The resulting coated glass has transmittances of 4.7% at 250–380 nm, 59.3% at 380–780 nm, and 9.7% at 780–2500 nm; excellent environment stability under accelerated aging conditions over 350 h; and also a ca. 50-fold lower fixed cost than commercial low-E glass. Moreover, a coated glass with a high pencil hardness of 9H was also fabricated via further spraying and calcinating of a PSZ coating as the cover layer, which is also the hardest coated solar glaze to our knowledge. The high solar-shielding performance and unprecedented low cost of the Ce and Sb co-doped SnO₂-coated glass, as well as the simplicity of its fabrication, exhibit great potential in energy-saving buildings and cars. Full article

Environmental comfort is fundamental for teaching and learning processes. This work focuses on identifying shortcomings and proposing improvements for educational buildings in the Andean equatorial climate. A quantitative experimental methodology was employed, which included collecting thermal comfort data to calibrate the use of the DesignBuilder v7 environmental simulation software. Issues with thermal weakness in the carpentry were identified, both due to the choice of materials and construction sealing. These are common weaknesses that arise in the context of the Andean Ecuadorian climate, but which affect moments of thermal discomfort during study hours. With the calibrated simulator, thermal improvements achievable by working on the carpentry to reduce infiltrations by half and improving glazing with double-glazed and triple-glazed windows, achieving even uniformity in thermal transmittance compared to other envelope materials, were analyzed. By reducing infiltrations alone, the average temperature increased by between 1.07 °C and 1.61 °C, surpassing the minimum comfort threshold and remaining within locally accepted temperatures throughout the day. With very-high-standard glazing, additional improvements are made, increasing the average temperature by an additional 0.30 °C to 0.69 °C, resulting in a less efficient alternative. Full article

Windows in new buildings in Korea are equipped with double or triple glazing, a low-E coating, and gas injection between the panes of glass, in accordance with the regulations for the reinforced insulation of windows. However, these windows have certain issues, such as thermal transmittance variations and injected gas leakage. In this study, we investigated the current status of double-glazed windows filled with argon gas and analyzed the actual deterioration degree in terms of insulation performance via field experiments and simulations. Accordingly, we manufactured a 26-millimeter low-E double-glazed window test specimen and conducted tests in accordance with the KS F 2278 standard. The test results indicated that the thermal performance decreased by 10.9% when the argon gas filling rate was reduced from 95% to 0%. The simulation results showed that the thermal performance of windows that were insulated using only glazing decreased by 22.6% with the decrease in the argon gas filling rate; the thermal performance of the double-glazed windows also decreased by 13.6%. A comprehensive analysis of the field surveys and simulations predicted a 92% probability that the argon gas filling rate of double-glazed windows would be below 65% by two years after completion, in addition to a ~4.3% decrease in thermal performance. Full article

The world is emphasizing the need for building design that considers energy performance to deal with climate problems. South Korea has constantly been tightening the design standards for saving building energy but with a focus on thermal performance and equipment systems. Accordingly, this study conducted an energy simulation experiment on office buildings with different window-to-wall ratios (WWRs) to propose a smart glazing plan to improve energy performance. An energy simulation experiment was performed on office buildings with varying WWRs to hierarchically analyze the influence of building window performance elements, including the heat transmission coefficient (U-value), visible light transmittance (VLT), and solar heat gain coefficient (SHGC), on building energy performance. The analysis showed that SHGC had the most significant impact on the heating and cooling load, by 22.13%, with the influences of the variables being 12.4% for the U-value, 4.78% for VLT, and 82.83% for SHGC. The results showed that the solar heat gain coefficient (SHGC) had the greatest impact on energy performance among window performance elements, and the effect increased significantly in certain WWRs. Moreover, to improve the energy performance of buildings with higher WWRs, it is essential to reflect the optimum composition of the U-value and SHGC on the window plan. This study’s findings propose measures to supplement existing window plans focusing on thermal performance. Furthermore, these results hold academic value in providing concrete grounds for that. Full article

This article presents an original study on the impact of climate change and the area of windows A_wi (factor X₁), the thermal transmittance coefficient of windows U_wi (factor X₂), and the coefficient of total solar transmittance factor of the glazing g_gl (factor X₃) on the index of annual usable energy demand for heating EU_H (function Y) of a single-family residential building in the climatic conditions of Bialystok (Poland), which were loaded with an equal gradual increase in average monthly external temperature by Δθ_e,n (factor X₄). Based on the results of the computational experiment, a deterministic mathematical model of this dependence was developed, and the effects of selected factors on the Y function were analyzed for the considered climatic conditions. Moreover, in cases of selected variants, the influence of the energy source on the amount of final energy used and CO₂ emissions was studied. It was found that an increase in the average monthly external temperature reduces the EU_H of the tested building by 8.4% per every 1 °C of increase in Δθ_e,n. The reduction in CO₂ emissions as a result of climate change is visible for systems with low efficiency and high emission factors (wood boiler), while in the case of pro-ecological high-efficiency systems (with a ground-source pump heat) it is inappreciable. Due to the need to decarbonize buildings, knowledge about the impact of the properties of windows, which are the weakest element in terms of heat loss through the building envelope, as well as the type of heat source on heat demand and CO₂ emissions, is very important for engineers and designers when making the correct decisions. Full article

This article aims to investigate the impact exerted by different types of covering an atrium with glazing on the energy performance of a kindergarten building, provided by the authors as a conceptual design. The considered types of atria included an open atrium, a glazed atrium, and an atrium that operated as a hybrid system. Additionally, the following aspects were taken into consideration: the effect of a glazing-integrated PV system (BIPV); the variety of thermal features represented by the inner boundary between the conditioned and the unconditioned space (U_iu); and the atrium space air-exchange ratio (n_ue) on the energy balance of the building. Energy performance indicators, including energy demands for space heating and cooling (Eu), delivered energy (Ed), and primary energy (Ep) indicators for heating and cooling mode were estimated for the moderate climates and two locations of the building model, i.e., for Warsaw (Central Poland) and Ahlbeck (Northern Germany). The research results prove that the glazed atrium exerts the most beneficial impact on the energy performance of the building. Nevertheless, certain variables must be considered, especially the air-exchange ratio of the atrium space, as they significantly influence the total annual energy performance. The results obtained with regard to the effect exerted by the presence of BIPV systems differ from those usually expected. This is due to the effect of the total solar-energy-transmittance value (g) modulation caused by the system and, finally, by a significant reduction in passive solar-gain harvesting, which is important for heating-mode results in examined climate conditions. Taking the present analysis into account, it can be concluded that the energy and environmental effects of the glazed integrated PV systems in temperate climates are strongly influenced by the environmental conditions, and, in some cases, these solutions may prove to be not efficient enough in terms of the energy and costs. Full article

One of the most important parameters that indicate the energy performance of a window system is the thermal transmittance (U-value). Many research studies that deal with numerical methods of determining a window’s U-value have been carried out. However, the possible assumptions and simplifications associated with numerical methods and simulation tools could increase the risk of under- or over-estimation of the U-value. For this reason, several experimental methods for investigating the U-value of windows have been developed to be used either alone or as a supplementary method for validation purposes. This review aims to analyze the main experimental methods for assessing the U-value of windows that have been published by national and international standards or as scientific papers. The analysis criteria include the type of the test in terms of boundary conditions (laboratory or in situ), the part of the window that was tested (only the center of glazing or the entire window), and the data analysis method (steady-state or dynamic). The experimental methods include the heat flow meter (HFM) method, guarded hot plate (GHP) method, hot box (HB) method, infrared thermography (IRT) method, and the so-called rapid U-value metering method. This review has been set out to give insights into the procedure, the necessary equipment units, the required length of time, the accuracy, the advantages and disadvantages, new possibilities, and the gaps associated with each method. In the end, it describes a set of challenges that are designed to provide more comprehensive, realistic, and reliable tests. Full article

Organic phase change materials, e.g., paraffins, are attracting increasing attention in thermal energy storage (TES) and thermal management applications. However, they also manifest interesting optical properties such as thermotropism, as they can switch from optically opaque to transparent reversibly and promptly at the melting temperature. This work aims at exploiting this feature to produce flexible silicone-based blends with thermotropic properties for applications in glazed windows or thermal sensors. Blends are produced by adding paraffin (T_m = 44 °C, up to 10 phr) to a silicone bicomponent mixture, and, for the first time, cetyltrimethylammonium bromide (CTAB) is also added to promote paraffin dispersion and avoid its exudation. CTAB is proven effective in preventing paraffin exudation both in the solid and in the liquid state when added in a fraction above 3 phr with respect to paraffin. Rheological results show that paraffin decreases the complex viscosity, but neither paraffin nor CTAB modifies the curing behavior of silicone, which indicates uniform processability across the investigated compositions. On the other hand, paraffin causes a decrease in the stress and strain at break at 60 °C, and this effect is amplified by CTAB, which acts as a defect and stress concentrator. Conversely, at room temperature, solid paraffin only slightly impairs the mechanical properties, while CTAB increases both the elastic modulus and tensile strength, as also highlighted with ANOVA. Finally, optical transmittance results suggest that the maximum transmittance difference below and above the melting temperature (65–70 percentage points) is reached for paraffin amounts of 3 to 5 phr and a CTAB amount of max. 0.15 phr. Full article

Spectral selective absorption film (SSAF), a solar control film, has a special energy-saving mechanism. In the previous studies of SSAF coated glazing systems, thermal parameters (global thermal transmittance (U) and solar heat gain coefficient (SHGC)) calculated by traditional algorithms were not verified. In order to evaluate the energy-saving effect of SSAF coated glazing systems accurately, U and the SHGC were calibrated and then used for energy consumption simulation. Firstly, the simulation models of the heat transfer process of SSAF coated glazing systems were established by COMSOL Multiphysics, considering simplified linear attenuation of radiative transfer. After being validated, the simulation models were used for the calibration of U and SHGC by the Multiple Linear Regression (MLR) model. As a result, the calibration coefficients of U and SHGC are 1.126 and 1.689, respectively. Secondly, the thermal parameters of SSAF coated glazing systems calibrated by the calibration coefficients were used for a building energy consumption simulation case. The result showed that the inner surface is the best coating position for single glazing systems (SG), while the outer surface is the best coating position for double glazing systems (DG) in hot summer and cold winter zone, hot summer and warm winter zone and the moderate zone of China. Full article

Current strategies for net-zero buildings favor envelopes with minimized aperture ratios and limiting of solar gains through reduced glazing transmittance and emissivity. This load-reduction approach precludes strategies that maximize on-site collection of solar energy, which could increase opportunities for net-zero electricity projects. To better leverage solar resources, a whole-building strategy is proposed, referred to as “Quality-Matched Energy Flows” (or Q-MEF): capturing, transforming, buffering, and transferring irradiance on a building’s envelope—and energy derived from it—into distributed end-uses. A mid-scale commercial building was modeled in three climates with a novel Building-Integrated, Transparent, Concentrating Photovoltaic and Thermal fenestration technology (BITCoPT), thermal storage and circulation at three temperature ranges, adsorption chillers, and auxiliary heat pumps. BITCoPT generated electricity and collected thermal energy at high efficiencies while transmitting diffuse light and mitigating excess gains and illuminance. The balance of systems satisfied cooling and heating demands. Relative to baselines with similar glazing ratios, net electricity use decreased 71% in a continental climate and 100% or more in hot-arid and subtropical-moderate climates. Total EUI decreased 35%, 83%, and 52%, and peak purchased electrical demands decreased up to 6%, 32%, and 20%, respectively (with no provisions for on-site electrical storage). Decreases in utility services costs were also noted. These results suggest that with further development of electrification the Q-MEF strategy could contribute to energy-positive behavior for projects with similar typology and climate profiles. Full article

The increasing regulatory requirements for energy efficiency in Europe imply a significant increase in insulation and solar control of buildings, especially in hot and semi-arid climates with high annual insolation such as the Spanish Mediterranean southeast. The consequences in architectural design to optimize compliance with the new technical and regulatory requirements of nearly zero-energy buildings are high. This paper analyzes the energy performance of a modern single-family house on the Spanish Mediterranean coast. The objective is to determine which design parameters most influence the energy improvement of this case study in order to establish design strategies that can be generalized to other new construction or energy retrofit projects, taking into account the specific characteristics of the warm and semi-arid Mediterranean climate. The scientific novelty of the work is to demonstrate that the design criteria of most modern single-family houses built or rehabilitated in the Spanish Mediterranean in the last decade comply with the energy efficiency requirements of Directive 2010/31/EU but are not specifically adapted and optimized for the special characteristics of the dry Mediterranean climate. This is the case of the house studied in this paper. The methodology used consisted of a systematized study of the main construction and geometric parameters that most influence the thermal calculation of this project: the thermal insulation thickness, thermal transmittance of the glazing, solar control of the glazing, total solar energy transmittance of the glazing with the movable shading device activated, size of glazing and the size of façade overhangs. The results obtained show that the use of mobile solar protection devices in summer, such as awnings or blinds, reduces the cooling need in summer up to 44% and the overall annual energy need (Cooling + Heating) up to 20%. This implementation is more efficient than increasing the thermal insulation of facades and glazing, reducing the size of windows or increasing overhangs. The most optimal solution is the simultaneous modification of several parameters. This reduces both heating need in winter and cooling need in summer, achieving an overall reduction in an annual need of 48%. This multiple solution improves the annual energy performance of the house much more than any solution consisting of modifying a single individual parameter. The results determine trends, explanations and deductions that can be extrapolated to other projects. Full article

In sunspaces, there is an observable temperature rise above the external air temperature, caused by solar gains and the buffering effect of their enclosure. In addition, their external partitions form a barrier preventing the direct influence of the external environment and delaying the natural deterioration of elevation surface. In the paper, the temperature rise in a glazed balcony attached to a typical flat in a multifamily building, together with the energy demand in the living zone, were assessed with the use of dynamic computer simulations. Ten variants of the sunspace casing were analysed, with different thermal and solar energy transmittance of the glazing (which is a novel subject in the research area). This enabled us to evaluate average values of the temperature reduction factor during the year and to choose the most efficient variant of the sunspace external partitions. It turned out to be an insulated, double-glazed casing with a spectrally selective coating (type O 21), combining high insulative properties with high solar transmittance. These features allowed the temperature in the sunspace to rise by almost 10°C (compared with the external air) and lower total energy demand in the flat by 33% (compared with a flat with an open balcony). Full article