Double Glazing Research Articles

Thermo-environmental performance of polycarbonate materials as a glazing substitute in hot climates

ABSTRACT Buildings consume substantial energy, primarily for cooling and heating, resulting in equivalent CO2 emissions. Proper building envelope design in hot climates is crucial for reducing heat transmission, especially in transparent glazed-dominated envelopes with low thermal insulation compared to opaque walls. Compared to conventional glass, this study investigates the impact resistance, thermal performance, and environmental impact of polycarbonate (PC) sheets used as exterior glazing for windows and skylights. The study conducted literature reviews, Solar Heat Gain Coefficient (SHGC) measurements, and energy simulations of PC alternatives using a hotel in Madinah. Findings indicate that all PC alternatives' thermal and environmental performance performed better than ordinary glass, reducing total energy consumption and greenhouse gas (GHG) emissions. Single glazing decreased energy from 1% to 15%, double glazing from 1% to 19%, and triple glazing from 1% to 20% as window glazing. Skylight glazing also lowered overall energy use and gas emissions, with single glazing reducing 2% to 28%, double glazing 3% to 42%, and triple glazing 4% to 49%. Furthermore, the 25mm 9 wall X-Structure PC sheet performed best for windows and skylights in all glazing systems (single, double, and triple). The PC sheets' thickness and section composition affect thermal and environmental performance.

Analysis of the influence of outer envelope structure on indoor thermal environment of zero energy building

Zero-energy building is the main development trend in the current construction field. Reducing the carbon emission of the building, enhancing the indoor comfort of the building, and improving the comprehensive performance of the building are the current research hotspots in the field of construction, and it is necessary to explore the impact of the envelope on the performance of the building as the main medium for the transfer of indoor and outdoor heat in the building. In this paper, zero energy consumption buildings in Northwest China are taken as the study application. Numerical simulation and experimental research are combined to compare and analyze the changes of indoor thermal environment under the conditions of external wall insulation layer thickness of 150mm, 140mm, 130mm and window-wall ratio of 0.36 and 0.5 in the heating season. The results show that the indoor comfort level of 130mm is lower than that of 140mm and 150mm external wall insulation layer thickness, and in winter, the increase of window wall ratio improves indoor thermal comfort. In general, increasing the thickness of external wall insulation layer and window wall ratio can be effective means to improve indoor comfort. However, blindly increasing the thickness of insulation layer and window wall ratio will only cause resource waste and cost increase, affecting the long-term development of zero-energy buildings.

Resilient heritage: Harnessing technology for sustainable conservation

Architecturally significant heritage buildings often struggle to meet modern energy efficiency standards. This study focuses enhancing the energy performance of the Polytechnic University of Tirana without compromising its historical integrity. Through detailed energy simulations using DesignBuilder software, the study evaluates the effectiveness of various double-glazing window configurations and internal shading systems. The results reveal that double-glazed units can lead to energy savings of up to 9.0%, particularly when using tinted, argon-filled glass. Shading devices, including fixed and automated internal louvres, provided additional savings between 4.3% and 7.8% by mitigating solar heat gain and improving thermal comfort. Also, the cost of each intervention is analyzed and savings per cost ratio ranging from €6,930 to €43,331 per 1% energy reduction is obtained. Notably, the economic analysis shows that simpler solutions, like air-filled double glazing and fixed louvres, offer a higher cost-efficiency. For the case study building, 16.53% energy savings may be obtained for a cost of €10,521 per 1% of reduction. The study's findings offer an example for future sustainable conservation projects, balancing historical preservation with energy efficiency. The results underscore the importance of targeted retrofitting in safeguarding cultural heritage while contributing to broader sustainability goals.

Evaluation the life cycle carbon emissions of the aerogel glazing under different weather conditions

Carbon emissions are widely recognized as the primary cause of global warming over the past few decades. The Aerogel Glazing System (AGS) stands out as one of the most advanced glazing systems currently available. In order to evaluate the carbon-saving potential of AGS, the life cycle carbon emission model of AGS was established. The carbon emission of production, transportation, construction, operation, maintenance, and waste disposal are considered. The results showed that AGS has higher carbon-saving potential. The life cycle carbon emissions of AGS in commercial, double glazing system (DGS), triple glazing system (TGS) are −144.8 kg CO2/m2, 593.6 kg CO2/m2, 250.8 kg CO2/m2 in Beijing horizontal direction. Under high temperature supercritical drying (in Commercial), low temperature supercritical drying, and freeze-drying, the life carbon emissions of AGS are lower compared to both DGS and TGS. Then the life cycle carbon emissions of AGS in different climates were analyzed. The results show that the life cycle carbon emissions of AGS under different climatic conditions are as follows (in ascending order): subtropical climate < polar climate < temperate climate < arid climate < tropical climate, with a maximum of 4929.9 kg CO2/m2 and a minimum of −634.5 kg CO2/m2. The use of AGS in tropical climate produced 5.9 times increase in life carbon emissions compared to its use in subtropical climate. In the heating-dominated climate, AGS has the greatest potential for carbon savings when orientated southwards. In cooling dominated climates, the carbon emissions are higher in the southward direction, with a weaker potential for carbon savings. Interestingly, in polar and tropical climates, increasing the aerogel thickness layer effectively reduces the life cycle carbon emissions of AGS. This study provides valuable insights for selecting sustainable curtain wall systems and window configurations, offering a pathway to minimize environmental impacts.

Towards A Design Approach to Achieve Environmental Safety in Diagnostic and Therapeutic Units in Hospitals Using Nanotechnology

In The environmental safety was investigated in this study, with an initial focus on defining the general concept of environmental safety. Subsequently, the study delved into the environmental safety within hospitals, particularly in diagnostic and treatment spaces. Air pollutants and their types were examined, along with permissible levels, emphasizing the adverse effects of increased pollutants on human health. Additionally, attention was given to the physical hazards within these spaces, such as temperature, noise, and lighting. In the context of studying diagnostic and treatment spaces in hospitals, a review was conducted on the currently used traditional finishing materials and an evaluation of their harmful effects. The concept of "sick buildings" and its impact on human safety was also explored. The study placed a particular emphasis on nanotechnology and how nano-materials can be employed to mitigate the detrimental effects of non-compliant "sick buildings" with environmental safety standards. Global examples of nano-applications were analyzed, along with an examination of a hospital in Egypt that utilizes nano-technology in its glass structure. Furthermore, a simulation was performed on a local hospital to measure the difference in carbon dioxide emission within the space. This comparison was conducted between the current state of the building using traditional finishing materials and the scenario where nano-alternatives are employed in the glass and thermal insulation of exterior walls.

Regulating the valence state of lead ions in lead aluminosilicate glass to improve the passivation performance for advanced chip packaging

Eliminating surface ion contamination, increasing the reverse breakdown voltage and reducing the leakage current are extremely important for semiconductor devices. Herein, we demonstrated that regulating the valence state of lead ions in lead aluminosilicate glass can efficiently improve the performance of glass passivation technique for chip packaging. It was found that heat treatment technique can be utilized to control valence state of lead ions from +4 into +2 in 20PbO-4.8Al2O3-75.2SiO2 (mol%) (PAS) glass powder, which induces transformation of [PbO3] units into stable glass former units of [PbO4] and generates a free state and charge compensator of Pb2+, therefore contributing to a more stable structure and discoloration of glass. As a result, the optical band gap of glass powder was enhanced from 4.1772 to 4.3184, which could significantly improve glass insulation. As a demonstration of chip packaging, PAS glass powder, after heat treatment processing into a paste for the passivation layer of metal–oxide–semiconductor (MOS) structure devices shows a tight and integrated structure and exhibits a lower fixed charge density from 3.97 × 1010cm−2 to 2.73 × 1010 cm−2. This work provides techniques to adjust the structure of glass to enhance the passivation performance of glass for chip packaging.

Thermal Performance Evaluation of TIM Combined with Residential Windows in Different Climatic Regions in Iran

Windows play a significant role in the increase and loss of heat from the building envelope and determine the quantity, quality, and distribution of daylight. A strategy that involves incorporating transparent insulating materials into a double-glazed window offers the potential to provide combined improvements in thermal and daylighting performance. The thermal properties of transparent insulation materials in windows depend on various factors, such as the type of insulation material, thickness, geometry and insulation structure, location, and orientation of the window, among others. The aim of this research is to optimize three criteria: "thickness," "location of transparent insulation relative to window layers," and "direction of the wall with transparent insulation of the building window." The goal is to minimize thermal loads and reduce energy consumption in residential buildings. To achieve this, a real model was selected, and Design Builder software was used to measure the "heating load," "cooling load," and the sum of these two loads as the "total thermal load" for all three criteria in three cities of Iran with different climates: Tehran (moderate climate), Ahvaz (warm climate), and Tabriz (cold climate). The results of the research showed that for the city of Tehran, 3-inch insulation in the middle of the double-glazed window and the south front is optimal. For the city of Tabriz, 5-inch insulation on the inner surface of the window and the western front is optimal. And for the city of Ahvaz, 3-inch insulation on the outer surface of the window and the eastern front is optimal. It is worth noting that the annual heating load and total annual heating load for all three criteria have the highest values in Tabriz city. Therefore, it is recommended to use HSNPS insulation in transparent windows to reduce energy consumption in Tabriz (cold climate).

Towards a quantification of thermal and thermomechanical stress for modules in building‐integrated photovoltaics configurations

AbstractDue to reduced rear‐side ventilation, building‐integrated photovoltaics (BIPV) are prone to higher operating temperatures, which may impact their long‐term performance and reliability. However, often overlooked in the study of thermomechanical stress in PV modules are the intraday temperature variations, resulting from factors such as cloud movements and subsequent changes in irradiance. This work proposes a statistical analysis of cell and module temperature measurements in single‐cell c‐Si modules on a test bench in Neuchâtel, Switzerland. The goal is to study and compare various BIPV‐relevant module topologies with a range of factors such as the insulation type, tilt angle, and glass thickness. The standard indicators such as the 98th percentile temperature and diurnal temperature variations are examined, as well as proposed new thermomechanical stress indicators based on temperature gradients and cell versus module temperature differences. Unexpectedly, results indicate that, considering the intraday temperature variations, close‐roof module configurations (with small ventilation gaps) are potentially at a higher risk of suffering long‐term thermomechanical fatigue than fully insulated modules, which are exposed to higher operating temperatures.

Research on energy-saving renovation of solar greenhouses based on multiple factors and multiple objectives

The applicability of the traditional energy-saving renovation method for greenhouses is limited and influenced by the subjective decisions of researchers. Therefore, in this paper, a multifactor and multiobjective unbiased evaluation method is proposed based on the orthogonal test and entropy methods to study energy-saving transformation of solar greenhouses. The results show that the thickness of the gas layer, type of front roof glass and thermal insulation material of the rear roof greatly influence energy consumption, accounting for 45.5 %, 34.4 % and 15.3 %, respectively, of the total energy consumption, followed by the type of gas, thickness of glass and thermal insulation material of the heat storage wall, accounting for 3.2 %, 1.1 % and 0.5 %, respectively, of the total energy consumption. Based on energy savings, carbon emission reduction, investment cost and payback period, all renovation cases are comprehensively analyzed by the entropy weight method. The results show that Case m is the best renovation case, i.e., the front roof comprises three-layer glass, the glass thickness is 3 mm, the width of the cavity is 6 mm, which is filled with krypton gas, the rear roof insulation material is 100-mm thick extruded polystyrene (XPS), and the heat storage wall insulation material is 100-mm thick expandable polystyrene (EPS). This renovation method provides a systematic and objective theoretical basis for energy-saving renovation of solar greenhouses in cold regions.

A Systematic Review of Climate Change Implications on Building Energy Consumption: Impacts and Adaptation Measures in Hot Urban Desert Climates

The climate change–built environment nexus is complex and intertwined. Recognizing the rising air temperatures and solar radiations owing to climate-induced global warming, it is critical to manage the increased building energy and cooling loads in the Middle East Gulf states’ hot desert climates (Bwh). One of the top climate priorities is to promote climate resilience by reducing risks and enhancing adaptation options. This study aims to systematically review the existing literature to document building energy performances in and the associated adaptation measures of the Middle East Gulf states, regarding the implications of climate change. It is accomplished by answering the following questions: ‘How well do we understand the effects of climate change on building energy use in hot urban deserts?’ and ‘What are the most appropriate adaptation strategies to reduce energy use in hot urban deserts?’. Using the Preferred Reporting Items for Systematic review and Meta-Analysis protocols (PRISMA), 17 studies on the influence of present and future weather scenarios on building performance are examined, considering variations in typology, methods, and input variables. Finally, the paper identifies the preferred methods and input variables for modelling building energy performance under predicted climatic changes. Passive design considerations are considered highly effective in mitigating and adapting to climate change implications. Thermal insulation and efficient window glazing are identified as the best-performing strategies, while the use of solar Photovoltaic (PV) is considered efficient in meeting the primary energy demands. The study’s findings can assist planners and designers in projecting future climatic influences on the energy usage of existing buildings.

Investigation of CCF with TGU as Inner Skin to Reduce Peak Operating Temperature for Thermal Comfort in an Indoor Environment in a Hot, Humid Climate

A closed cavity facade (CCF) is “a sealed, non-ventilated cavity with an automated shading device that, at its simplest, consists of double or triple glazing on the inside and single glazing on the outside”. The dynamic properties of this technology enable the fluid control of solar energy and daylight entering the structure. Several CCF designs were investigated in EnergyPlus and DesignBuilder, and the outcomes were compared to the present state (a single-glazing unit (SGU) with grey coating). The investigation was founded on a case study of a Penang Island, Malaysia, condominium. Comparing CCFs with traditional SGU systems reveals significant thermal performance and occupant comfort enhancements. CCF configurations performed well throughout the year, with maximum operational temperature reductions 40–91% better than traditional SGUs in Malaysia's humid tropical climate. Further investigation revealed that the glass coating and sun shading capabilities substantially contribute to reducing the interior temperature and enhancing the comfort of the building's occupants. The greatest performance was achieved by combining a nanocoating (83/58) and an E-low coating (83/23) (Tvis/Tsol) with a Venetian blind. In light of this, it is essential to carefully consider which coatings to use when installing CCF in such conditions. In all of these regards, the study concentrates on the fact that developing and implementing suitable combinations of a new closed-cavity facade for Malaysia's climate can result in substantial gains. The results demonstrate that building operational temperatures and comfort can be enhanced, highlighting the need for innovative glazing technology.

Anomaly in the relation between thermal conductivity and crystallinity of silicate glass-ceramics

Thermal conductivity is a key property of oxide glass, especially for building applications such as thermal insulation materials and windows or glazed facades. However, this property is difficult to be predicted since it depends on several factors such as the degree of order/disorder and porosity. Here, we report on the effects of crystallization, crystalline phase, and crystal size on the thermal conductivity of a melt-quenched silicate glass. These effects were studied by heat-treating the glass at the onset crystallization temperature for different durations to vary crystallinity in the samples. The results show a general increase in thermal conductivity with crystallinity and crystal size in the nano-range (<75 nm). The growth of devitrite and combeite phases in the glass has a great impact on the thermal conductivity. Interestingly, an anomaly of thermal conductivity is found, i.e., the thermal conductivity of the sample with a relatively low crystallinity of <15 % is reduced by >20 % compared to that of the pure glass phase. This may be attributed to the grain boundaries between amorphous and crystalline phases, which scatter the phonons and thus reduce the thermal conductivity. These results imply that nano-crystallization in window glass might be a useful way to reduce the heat loss from glazed facades in the building envelope.

Effects and Improvements in Carpentry for Thermal Comfort in Educational Spaces in Andean Mild Equatorial Climate

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.

Sound Insulation of Single-Layer Glazing, Single- and Double-Glazed Windows

The analysis of known analytical solutions to the problem of calculating transmission the sound insulation of one- two- and three-layer glazing in comparison with the results of laboratory measurements is presented. The wave theory of sound transmission through single-layer and multi-layer enclosing structures with air gaps is used. Based on calculations of sound insulation of single-layer glazing, it is shown that the theory underlying the methodology of GOST R EN 12354-1–2012 “Acoustics of buildings. Methods for calculating the acoustic characteristics of buildings based on the characteristics of their elements. Part 1. Sound insulation of air noise between rooms”, most adequately takes into account the processes of non-resonant and resonant sound transmission. Its use in the formulation of models of sound transmission through double and triple glazing, taking into account internal losses and the influence of resonant processes, made it possible to obtain analytical solutions to the problem of sound insulation of single-chamber and double-chamber double-glazed windows, which showed good convergence with the experimental results. The proposed method for calculating sound insulation through single- and double-chamber double-glazed windows can be used in engineering calculations after additional studies of internal losses in multilayer glazing, as well as additional measurements of a number of “standard” types of glazing to verify the methodology.

The impact of energy policy on traditional buildings: Towards a holistic decision-making framework for retrofitting: Part 1

The Energy Performance of Buildings Directive (EPBD) is the European Union’s main policy instrument for reducing the built environment’s contribution to climate change. Energy Performance Certificates (EPC) are a tool of this policy, providing buildings with a performance rating. In the UK these have become the benchmark by which the Minimum Energy Efficiency Standards (MEES) are judged, rendering residences lower than an E illegal to rent out. This has pushed property owners to undertake energy retrofitting interventions to ensure compliance. In traditional buildings this is potentially problematic. Buildings of this type rely on permeability to control moisture dynamics; the insertion of less permeable barriers can interrupt their internal hygrometry leading to condensation, damp and decay. As a result, subsequent damage to the building fabric can bring energy policy into conflict with heritage conservation. Existing frameworks that attempt to mitigate the tension within these agendas often fall short in explicitly considering the the problem holistically. This research first asks if pressure from policy is leading to incompatible retrofits. Secondly, it aims to develop a holistic framework that unites heritage and energy agendas with current policy. An inductive, pragmatic approach was undertaken. Using a historic estate’s residential portfolio as a case study, condition surveys were carried out to assess whether properties retrofitted with secondary glazing were experiencing problems with condensation. The results of this were significant, supporting the argument that energy policy is driving incompatible retrofitting interventions. Exploratory data analysis was carried out on an existing EPC dataset to highlight inconsistencies with the EPC methodology. Finally, these findings were combined with questionnaire survey results, targeted at both professionals and occupants, to inform a decisionmaking framework that incorporated energy efficiency, heritage values, LCC, building assessment, occupant behaviour, with a feedback loop promoting a bottom-up approach to policy. This issue contains Part 1 which will set the scene, with Part 2, to be published in the next issue, presenting the methodology and results.

Thermal characterization of a novel heated glass element

Although the U-value of glazing has improved significantly in the last decades, the thermal transmittance of windows remains relatively high compared to opaque elements of the thermal shell. Consequently, glazing has a relatively low interior surface temperature in the heating season, which can cause thermal discomfort. A novel heated glass element has been developed, allowing for the control of its interior surface temperature. In-situ measurements were conducted on a heated glass element, with the objective to (i) characterize its thermal behaviour, (ii) assess its thermal performance and (iii) to assess its impact on thermal comfort. The examination of heating-up and cooling-down curves of the heated glass element revealed that cooling-down is a slower process (τ2 of 100 – 145 minutes) than heating-up (τ2 of 70-85 minutes). In terms of thermal performance, it is shown that most of the heat provided by the heated glass element is effectively directed towards the room, rather than lost to the outdoor environment. The efficiency depends on the temperature difference between interior glass surface and the room, with efficiencies of 58 – 65% reached at surface temperatures of 23 - 25 °C, and efficiencies of 90% reached at surface temperatures of 39 – 43 °C. Comparative measurements of thermal comfort in a room with the heated glazing, and in a room with conventional triple glazing show an improvement in operative temperature.

Basic study of practical prediction of sound insulation performance of double-glazed window

Since double-glazed glasses have superior thermal insulation performance compared to single-glazed glasses, they are widely employed for windows in recent buildings. However, the double-glazed glasses used in general buildings have mass-air-mass resonance at around 200-400 Hz, and, at those frequencies, their sound reduction indices are often lower than that of single-glazed glasses that have the same weight. In designing an indoor acoustic environment, it is helpful to have a practical method to predict the sound reduction index of a double-glazed glass window, including the resonance. In this study, at first, measured values of actual double-glazed windows are compared with calculated values of the existing sound transmission theories for double plates and applicability of the theories to double-glazed windows are investigated. Next, in order to obtain a practical prediction of the sound reduction indices of double-glazed windows, some measured values of double-glazed windows are collected from a manufacturer's database and the characteristics of the sound reduction indices are discussed.

Thermal conditions in workspace centre and adjacent to inclined glazed façade of a green-certified office building in the tropics

This paper aims to assess the effectiveness of incorporating inclined glazing with double low-emissivity (low-e) glazing, in glazed, green-certified office buildings in Malaysia. The study was conducted in an open workspace facing south and west. Comparisons were conducted between measurements made on weekdays when cooling systems were active and weekends when they were not in use. The analysis considered two different zones based on the proximity to the glazed facade: the adjacent zone and the central zone. The thermal performance of the glazed facade and the indoor thermal conditions were measured from July 25th to August 30th. The findings indicate that the building successfully maintains indoor air temperature within the recommended thermal range of 23 °C–26 °C, as specified by the Malaysia Standard. However, it was noted that the air velocity fell below the required level for optimal indoor air circulation. Measuring the globe temperature showed a remarkable difference, with the adjacent zone experiencing 4.1 °C higher temperatures due to radiant heat from the glazing. Additional research is suggested to assess the effectiveness of inclined and double low-e glazing in hot–arid climates like Saudi Arabia.

Assessing different glazing types for energy savings and CO2 reduction in a tropical climate: A comparative study

Energy efficiency in buildings and the mitigation of CO2 are key factors in the advancement of contemporary architecture, which includes aesthetic elements such as skylights, façades, and windows. Therefore, in this work the impact of different glazing types on energy savings and CO2 reduction was presented. A comparative analysis was conducted taking into account the climate-oriented approach in a specific climate context, Aw Köppen Climate Classification. Based on numerical results of the conjugate heat transfer in a two-dimensional geometry in a transient state, first, the glazing thermal performance under extreme weather conditions was evaluated, subsequently, an annual thermal evaluation was conducted. Triple glazing was highlighted as an effective option as it reduced heat loss by 56.5 % on the coldest day and reduced heat gain by 31.0 % on the warmest day in Mérida, Yucatán. Triple glazing also showed efficiency in reducing the total heat flux per unit area by 32.7 % under extreme temperature and solar radiation conditions, coldest day – south orientation and warmest day – west orientation. While glazing orientation showed a significant role in overheating, triple glazing decreased electricity consumption and CO2 emissions by 29 % per year, making it a leading choice for sustainable architecture.

Thermal Performance Analysis of Windows, Based on Argon Gas Percentages between Window Glasses

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.