Curtain Wall System Research Articles

Thermal-deformation behaviors of the primary sealants in double, triple, and multi glazed insulating glass units

Polyisobutylene (PIB), commonly used as the primary sealant of double, triple, and multi glazed insulating glass units (IGUs), provides the key moisture barrier function and determines the expected lifespan of the IGUs and even the entire glass curtain wall systems (GCWSs). Slipping and debonding of the PIB, caused by temperature changes, have resulted in numerous instances of premature failure of building envelopes. However, available research is inadequate in accurately evaluating the service environment of IGUs and thermal-deformation behaviors of this energy-saving building material. This paper presented a simplified method for analyzing the thermal environment of IGUs, considering outdoor air temperature, solar radiation, wind speed, and angle to the horizontal. A numerical modeling method was proposed and validated with the heat transfer tests. Three finite element (FE) models were built and utilized for the precise analysis of temperature-induced deformations of double, tripled, and quadruple glazed IGUs. Simplified calculation formulas for the maximum thermal deformation of PIB in the X and Y directions under different temperature conditions were obtained, taking a new concept “cavity-to-pane ratio” into consideration. Finally, the relationship between the PIB’s temperature-induced deformation and its probability was proposed. The results show that the IGUs in Beijing suffer more than 22 % of their time in harsh service conditions where the difference between indoor and outdoor temperatures exceeds 20 °C. For DIGUs, the maximum temperature-induced deformations of the PIB in X (along the short side of the panel) and Y (along the long side of the panel) directions are 0.142 and 0.214 mm, respectively, corresponding to shear strains of 28.4 % and 42.8 % for the PIB with a thickness of only 0.5 mm. For TIGUs, the maximum deformations increase to 0.159 and 0.239 mm, corresponding to shear strains of 31.8 % and 47.8 %. For QIGUs and the other multi-glazed IGUs, these values can increase to 36.8 % and 55.4 % or more. The methodology proposed in this paper aims to lay the groundwork for further addressing premature failure issues and optimizing edge bond constructions of multi-glazed IGUs.

Assessment of cantilevered curtain wall system supported by tension rods for an enclosed circular building

Curtain wall systems have undergone significant advancements to meet the evolving architectural requirements and achieve aesthetic appeal and functionality in buildings worldwide. These non-structural enclosures, typically constructed with lightweight materials like glass or metal panels, contribute to the visual appeal of high-rise structures while providing numerous benefits, such as ample natural light and unobstructed views. The current paper focuses on analyzing and designing a cantilevered curtain wall system supported by tension rods for the auditorium façade at a simulation centre. The curtain wall surrounds the entire primary structure of the building, which has a circular layout. The study uses numerical modeling with the Robot software to analyze stresses and deflections in the glass, tension rods, mullions, and transoms while considering a wind load of 1.6 kPa. According to the findings, tempered laminated glass that is 19.52 mm thick satisfies the Ultimate Limit States (ULS) and Serviceability Limit States (SLS). Under the limit states, the Technal system (FM169) reinforced with steel tubes can transfer the design loads. The steel framing system that supports the tension rods and transfers the load of the curtain wall to the main structure is likewise considered safe. The structural integrity of the curtain wall is ensured by the prescribed requirements for the connections, which include a 5 mm fillet weld with a throat thickness of 3.5 mm, 20 mm diameter tension rod (Kin long system), and 8 mm thick MS plates with channel brackets. This research expands the practical application of cantilevered curtain wall systems of buildings with enclosed circular layouts.

Automated Defect Detection on Dry-Hanging Stone Curtain Walls through Colored Point Clouds

Stone curtain walls are widely used in contemporary architectures; however, their regular inspection is always labor-intensive, time-consuming, and hazardous due to the complex and enclosed spatial structure of these high-rise building enclosures. To address this issue, this study proposes an automated and novel inspection method, which is composed of the following three steps: First, we utilize 3D laser scanning technology to capture colored point cloud data of the stone curtain wall system; subsequently, by extracting and processing the integration of color and depth information, the stone panels and end sealants are precisely segmented; finally, various defects, such as cracks, unevenness, and irregularities, are automatically identified through artificial intelligence algorithms in a timely manner. To validate the proposed method, an on-site experiment was carried out to demonstrate the effectiveness in detecting multiple defects concurrently on stone curtain walls. The experimental results showed that our proposed method could provide a non-contact and automated inspection alternative for all the stone curtain walls with a high accuracy of anomaly detection, facilitating rational maintenance plans and strategies to ensure the safety and performance of these modern building enclosures.

Investigating Factors Impacting Power Generation Efficiency in Photovoltaic Double-Skin Facade Curtain Walls

Photovoltaic double-skin glass is a low-carbon energy-saving curtain wall system that uses ventilation heat exchange and airflow regulation to reduce heat gain and generate a portion of electricity. By developing a theoretical model of the ventilated photovoltaic curtain wall system and conducting numerical simulations, this study analyzes the variation patterns of the power generation efficiency of photovoltaic glass for different inclination angles, seasons, thermal ventilation spacing, and glass transmittance in the photovoltaic double-skin curtain wall system. The results indicate a positive correlation between the surface temperature of photovoltaic glass and both ground temperature and solar radiation intensity. Additionally, photovoltaic power generation efficiency is generally higher in spring and autumn than in summer and winter, with enhanced power generation performance observed. At an inclination angle of 40°, photovoltaic panels receive optimal solar radiation and, consequently, produce the maximum electricity. Furthermore, as the ventilation spacing increases, the efficiency of power generation initially rises, reaching a peak at approximately 0.4 m, where it is 0.4% greater than at a spacing of 0.012 m. For a photovoltaic glass transmittance of 40%, the highest photovoltaic power generation efficiency is 63%, while the average efficiency is 35.3%. This has significant implications for the application and promotion of photovoltaic double-skin glass curtain walls.

Noise control for curtain wall construction in residential buildings - a retrofit solution

In modern high-rise residential buildings, designers and architects utilize curtain wall construction either for the entire building or a portion of the building to achieve the desired visual impact in an urban setting. This poses significant challenges to satisfy the building code acoustical requirement (e,g., sound transmission class) between residential suites on adjacent floors. Apparent sound transmission class tests were completed after the curtain wall system was installed and concluded non-compliance with the Ontario Building Code acoustical requirement. A retrofit noise mitigation option was proposed and implemented. The ASTC field test was repeated and concluded compliance with the building code acoustical requirement.

Bio-curvilinear shading device for cooling load reduction in office buildings assessed by a novel energy simulation framework

Excessive heat accumulation is one of the main challenges in office buildings with curtain wall systems. This challenge requires a staggering amount of cooling energy, especially in desert and temperate climate zones. Hence, an effective and practical shading device is necessary to address this issue using a bio-inspired strategy to reduce cooling energy consumption and enhance sustainability. This study uses a Bio-Curvilinear Shading Device (Bio-CSD) to improve cooling energy efficiency, cost-effectiveness and CO2 reduction in the desert and temperate climate zones in Iraq. To alleviate overheating issues, we designed a Bio-CSD and a modified Bio-Curvilinear Shading Device (mBio-CSD) from a cactus, namely the Ogonchu plant (Pilosocereus chrysostele). Fifty-one scenarios were investigated to examine the prevalence of three distinct office building typologies: linear [T1], concentric [T2], and courtyard [T3]. The Bio-CSD and the mBio-CSD were simulated using a novel energy simulation framework for curvilinear shading devices using IDA Indoor Climate and Energy (ICE) software v4.8. Our findings revealed that the Bio-CSD outperforms a Rectilinear Shading Device (RSD) under identical conditions with the same surface area. The Bio-CSD allows maximum cooling energy savings of 31 %, 24 %, and 22 % and 23 %, 19 %, and 16 % for the three office building typologies (T1, T2 and T3) in temperate and desert climate zones, respectively. Our Bio-CSD can be a cost-effective and eco-friendly solution to mitigate overheating issues while ensuring more natural light penetration during winter, with reduced material use and lower costs.

Research on the Current Situation and Calculation Method of Carbon Emissions Assessment for Building Curtain Walls

Curtain wall systems stand out as a pivotal domain within the construction sector’s endeavors towards energy efficiency and carbon mitigation. To refine the evaluation framework for carbon emissions within this industry, this paper explores the calculation and assessment method for building curtain walls. The article first reviews the current research status regarding carbon emissions from materials and the impact of curtain walls on buildings in the operational stage. Based on lifecycle theory, the carbon emissions from building curtain walls are divided into six stages: material acquisition, processing and production, installation and construction, transportation, use and maintenance, and dismantling. On this basis, this paper proposes a method for calculating carbon emissions from building curtain walls. Following that, a case study is conducted using a specific glass curtain wall project for illustrative analysis. The results indicate that the carbon emissions from the material acquisition stage constitute approximately 90% of the total, serving as the primary source of carbon emissions for glass curtain walls. Furthermore, the scientific application of photovoltaics can significantly reduce the carbon emission levels of building curtain walls. Finally, an analysis was conducted on the current issues existing in the evaluation of carbon emissions.

Design and Simulation for Technological Integration of Bio-Based Components in Façade System Modules

Driven by environmental sustainability concerns, the integration of bio-based components in curtain wall systems is gaining traction in both research and the construction market. This paper explores the development and validation of a bio-based façade system within the Basajaun H2020 project (2019–2024). The project aimed to demonstrate the feasibility of introducing environmentally friendly bio-based components into the mature curtain wall façade industry. The paper focuses on identifying technological solutions for replacing key components such as frame profiles, insulation, and the tightness system with bio-based and less environmentally impactful alternatives, presenting the results achieved in the façade system design of the Basajaun project. These solutions aimed at creating a bio-composite-based curtain wall façade that adheres to the current building envelope standards and normative, implementing diverse façade typologies for vision panels, opaque sections, and integrated windows and, moreover, engineering the prefabrication process for industrialization and enabling wider market replication and simplified transport and installation. The results demonstrate that the Basajaun façade successfully integrates selected components and meets the performance requirements set by regulations: the façade is designed to withstand a maximum and typical wind load of 3.5 kN/m2 and a typical load of 1.5 kN/m2, the weighted sound reduction index obtained is Rw = 44 dB, and the thermal transmittance of the vision façade is 0.74 W/m2K while that of the entire opaque façade is 0.27 W/m2K (an additional internal wall is required to achieve the requested thermal transmittance)—the values are in accordance with reference standards and design requirements. However, questions remain regarding the workability of bio-based profiles as a commercially viable, ready-to-market solution that can replace traditional aluminum profiles in the curtain wall façade industry.

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.

Prefab Facades – From Prototype to Product?

Building envelopes are not only the prime element of the exterior aesthetic quality of buildings; they have also become a major driver both for building construction cost and operational performance. The importance of prefabrication is growing in the building industry as it allows faster, high-quality, and cost-effective construction while reducing risks associated with onsite labour. Although prefabrication for structural components is a relatively recent development, it has been widely used in the manufacturing of building envelopes for many years, particularly in the case of unitized curtain wall systems. However, whether using prefabricated components or not, façade design development remains a challenge due to the need for façade engineers to rapidly develop technically viable and financially feasible solutions that achieve the desired architectural design intent. Particularly at the early stages of the design process, the turnaround for multiple iterations is often fast-paced, and abortive work is, therefore, not uncommon. This paper outlines an approach to addressing this challenge, attempting to bridge the gap between façade design, fabrication, and installation. A new design approach and tools are presented that allow designers to iteratively validate concepts based on a pre-engineered system that is optimized for performance and take fabrication, transport, installation costs, maintenance, and circularity into account. As a result, the tool/design workflow will ensure consistent quality, meeting budgets and timelines while enhancing material efficiency and fostering energy-conscious and circular envelope design approaches.

Optimizing hybrid ventilation and daylight-linked dimming control for carbon reduction and thermal comfort in a subtropical high-rise office building

The dominant contributors to electricity consumption in existing buildings are air-conditioning and lighting systems. This study aims to optimize hybrid ventilation and daylight-linked dimming control in a subtropical high-rise office building. The objective is to reduce carbon emissions while ensuring thermal and visual comfort. These two strategies can be retrofitted in a typical curtain wall system with vertical windows without encountering any technical limitations. EnergyPlus is used to analyze the impact of these strategies on enhancing thermal comfort and illuminance while achieving electricity savings in the high-rise office building. Based on the typical meteorological year of Hong Kong, using natural ventilation in perimeter zones can reduce the energy use intensity (EUI) by 2.6 to 3.41 % for 30.09 to 34.97 % of total operating hours, depending on window-to-wall ratios (WWRs). Furthermore, daylight-linked dimming control in perimeter zones can reduce EUI by 18.91 % to 21.9 % in the HVAC portion and 8.09 % to 12.25 % in the lighting portion during 91.39 % to 98.28 % of total operating hours. Using daylighting with a high WWR helps reduce 6.31 to 9.21 % in total greenhouse gas emissions. The study also develops a logistic regression model using three climatic variables to predict the natural ventilation status. Overall, the use of daylighting greatly improves the percentage of acceptable predicted mean vote (PMV), with the greatest improvements observed in perimeter zones facing east and west on the middle floors. However, the combined application of both strategies results in a tempered improvement. The novelty of this study lies in providing guidance on suitable WWRs for implementing both strategies to achieve carbon reduction. Moreover, the significance lies in providing a quantitative assessment of how enhanced ventilation and lighting controls contribute to lower carbon emissions while improving thermal comfort.

A three-dimensional steady-state heat and vapour transport model to assess the risk for interstitial condensation in building enclosures

The article presents a practical 3D heat and vapour model to estimate the risk for interstitial condensation in building enclosures. The model is in fact a three-dimensional implementation of the Glaser method. In the first part of this article the modelling assumptions and solution technique are outlined. Next, the model is validated against an example from the literature. The third part of the article zooms in on the applicability of the proposed model in comparison to more complex hygrothermal models. Both the weaknesses and the strengths of the methodology are discussed. This section reviews the circumstances in which the model can be used safely and when a more detailed analysis is preferable. Finally, the article presents an actual case whereby the applicability of the model is demonstrated by making design decisions for the energetic retrofit of a curtain wall system.

An advanced exhausting airflow photovoltaic curtain wall system coupled with an air source heat pump for outdoor air treatment: Energy-saving performance assessment

Building integrated photovoltaic (BIPV) and air source heat pump (ASHP) technologies have emerged as promising solutions for building energy conservation. However, traditional solar buildings face limitations such as overheating, limited efficiency, and singular functionality; additionally, ASHPs suffer from a low coefficient of performance (COP) due to high condensing temperatures or low evaporating temperatures; the process of outdoor air handling proves energy-intensive. To address these challenges, this study proposes an innovative exhausting ventilation PV curtain wall system coupled with ASHP units (EVPV-HP) for outdoor air treatment. This system features a fine combination of PV cooling, supply air reheating, and heat recovery from both the PV facade and exhaust air. The mathematical model of the BIPV curtain wall, based on energy balance equations, is developed and solved using Matlab programming. This model is then combined with the ASHP system model established in TRNSYS to predict the year-round energy performance of the hybrid system. The findings demonstrate that the EVPV-HP system achieves seasonal energy efficiencies of 5.08 for cooling and 4.06 for heating operation modes. Compared to a conventional system, the EVPV-HP system enhances yearly energy efficiency by 17.05 % owing to increased PV production, reduced air-conditioning load, and improved COP. Furthermore, parametric analysis suggests that the system exhibits improved performance under higher solar irradiation and hotter weather conditions during summer. Conversely, in winter, the system performs better under lower ambient temperatures with incident radiation around 800 W/m2.

Test study on performance of U80 standardized glass curtain wall system

In order to study the air infiltration performance, water penetration performance, structural performance under wind pressure and seismic inter-story drift performance of U80 standardized glass curtain wall system, one full size test specimen was designed according to the actual engineering situation. The test specimen was composed of six-unit curtain walls with exposed frames and six-unit curtain walls with concealed frames. According to the specification of United Stated, the various performance of the test specimen was investigated. The results show that the rate of air leakage of the specimen is within allowable values under design pressure. No water leakage is observed when the water penetration tests with static and dynamic pressure tests. During the structural performance tests at 100% design wind pressure, the deflections of framing members as well as glass panels are all within the allowable deflection limits. No breakage is observed under the 150% design wind pressure. Permanent deformations of framing members remain less than 0.1% of clear span. After 3 cycles of elastic and inelastic inter-story drift performance tests, no damage is observed. The U80 standardized glass curtain wall system has great air infiltration performance, water penetration performance, structural performance and seismic inter-story drift performance. And it can be used in the practical engineering.

A Shingled Glass Envelope System Constructed from Reclaimed Insulated Glass

This paper presents a new approach to the design and construction of glazed building envelopes using salvaged insulated glazing units from demolition sites or surplus supply. Typically, Insulated Glazing Units (IGUs) are sent to landfill. Contemporary Architectural glazing is floated using virgin sand melted at 1700°C, a high energy extractive process. Obsolete architectural glass sent to recycling plants is not fed back into new float glass, rather it is downcycled to products such as glass bottles. This paper introduces a pathway for reusing obsolete and irregular Insulated Glazing Units into new curtainwalls; a pathway that currently does not exist. We demonstrate that the carbon footprint of glazed curtainwall could be halved by utilizing reclaimed IGUs. The system is a high-performance enclosure with weather tight compression gaskets and overlapping IGUs for thermal insulation and operational energy advantages over typical curtainwall systems. The system involves a computational configuration process for determining the best fit assembly of salvaged glass from a digitized inventory. The shingled glass façade system could be used in various applications, ranging from corporate offices to storefronts. This paper presents a one-to-one proof of concept, made from reclaimed IGUs of irregular size, collected in Lewes (UK).

A retrofitting framework for improving curtain wall performance by the integration of adaptive technologies

Energy efficiency and the reduction of carbon emissions have become the main climate goals for newly constructed or existing buildings. In the building sector, curtain walls (CWs) account for the majority of unwanted solar heat gain and consume most of the energy used. In this context, adaptive technologies (ATs) offer a wide range of alternative solutions to improve the performance of CWs. This study aims at developing a comprehensive framework for retrofitting CWs through the integration of ATs. Based on a comprehensive analysis of previous literature, the proposed three-stage framework provides a guide for enhancing the performance of CWs by evaluating and comparing retrofitting scenarios using ATs. The three stages include pre-retrofit survey, retrofit process, and monitoring process. To achieve this goal, curtain wall systems, retrofitting levels, and sub-practices are discussed. The integration ability of ATs into CW systems is assessed according to functional, structural, and technical properties. Integration scenarios are evaluated based on SWOT analysis, performance criteria, adaptive parameters, and retrofitting practices to assess their efficiency. Results show that integration scenarios of materials like electrochromic and semi-transparent photovoltaic glazing are applicable to all CW systems with remarkable performance enhancement. Phase change materials and liquid infill tunable glazing are the least applicable materials. Integration scenarios of adaptive systems involving green walls and dynamic shading devices provide the greatest functional benefits. Whereas, algae facades should only be installed in newly constructed buildings. In conclusion, the study proves that the integration of ATs into CWs offers promising potential for improving CW performance.

Understanding client satisfaction of prefabricated curtain wall in Hong Kong using XGBoost and Pearson correlation

PurposeThe unitized curtain wall system (UCWS), a symbol of modern architecture, is gaining popularity among prefabricated components. Previous studies have focused on both construction technology advances and material selection strategies to facilitate the UCWS. However, the topic of client satisfaction, which drives industry development by targeting clients' demands, has gone unnoticed. Therefore, the current study aims to investigate client satisfaction with UCWS products in Hong Kong by finding its influential factors.Design/methodology/approachA systematic review was employed to first identify the influential factors. A semi-structured interview was employed to validate the reliability of the extracted factors. The machine learning algorithm Extreme Gradient Boosting (XGBoost) and the Pearson correlation were then employed to rank the importance and correlation of factors based on the 1–5 Likert scale scores obtained through a questionnaire survey.FindingsThe findings revealed that “reduction in construction time” and “reduction in construction waste” are the most important factors and have a strong positive influence on client satisfaction.Originality/valueUnlike previous studies, the present study focused on a novel research topic and introduces an objective analysis process using machine learning algorithms. The findings contribute to narrowing the knowledge gap regarding client preference for UCWS products from both individual and collaborative perspectives, providing decision-makers with an objective, quantitative and thorough reference before making investments in the curtain wall management development.

Seismic behavior of a fully tempered insulating glass curtain wall system under various loading protocols

AbstractThis paper investigates the seismic behavior of a glass curtain wall system under various loading scenarios. Experimental set‐ups and approaches were developed to test full‐scale fully tempered (FT) insulating glass curtain wall systems subjected to three loading protocols: quasi‐static in‐plane loading, dynamic in‐plane loading, and dynamic coupled in‐plane and out‐of‐plane loading. A refined finite element (FE) model was developed to understand the behavior of the system. The average drift associated with glass cracking and fallout was found to be nearly identical for quasi‐static and dynamic in‐plane loading, indicating that in‐plane floor accelerations exerted marginal influence on the failure of the glass curtain walls. Bi‐directional loading led to an approximately 30% decrease in the glass fallout drift compared with in‐plane loading. This is because the out‐of‐plane drift placed an increased stress demand on the glass panel, as indicated by the FE analysis. Both the experimental tests and FE analysis revealed that the ASCE 7–16 formula, which is used to calculate the drift of contact between the glass and frame, is nonconservative as it does not consider the deformation of the surrounding frame and the friction between the gasket and the glass. The failure mechanism of the glass panel was caused by the stress concentrations at the diagonal corners due to glass‐to‐frame contact. The FE analysis indicated that the interactional effect among different glass units was negligible, and the glass panels exhibited a similar stress state regardless of their positions.

BIPV Generation Efficiency Optimal Scheme—— Take Jiangning District of Nanjing City for Example

Building Integrated photovoltaic (BIPV) is more and more applied to the construction field with its advantages of being close to the load center, saving urban land and building materials. Especially under the current goal of 'carbon peak' and 'carbon neutrality', the integration of photovoltaic buildings is one of the important ways to achieve the effective application of renewable energy in buildings. But at present, the lack of relevant application cases of the technology, many owners interested in BIPV have remained on the sidelines. This paper mainly focuses on the economic and environmental benefit evaluation of the roof and curtain wall system of BIPV. By comparing the economic benefits and investment payback period, the owners provide the optimal investment plan, and analyzes the significance of 'two-carbon policy' by calculating the environmental benefits of BIPV. In this paper, Jiangning District of Nanjing city is taken as the pilot object to analyze the benefit of BIPV, and proposed the optimal design strategy of building photovoltaic integration suitable for this area through the benefit comparison of different schemes. In the roof and curtain wall benefit evaluation when we use the photovoltaic garden analysis site for solar radiation estimates, and then get the whole life cycle of photovoltaic system capacity, as the basis of economic benefit evaluation, then through the query related data to save the total coal as the basis of environmental benefit evaluation, combined with the project investment payback period, economic benefits and environmental benefits of comprehensive evaluation of the final plan. Through the above economic benefits and environmental benefits data comparison, photovoltaic roof has more investment value than photovoltaic curtain wall in both economic and environmental aspects. Taking Jiangning District of Nanjing city as an example, this paper illustrates the broad prospect of BIPV, and also provides a relatively clear data support and case reference for the promotion of BIPV nationwide in the future.

Single- and double-inlet PV curtain wall systems using novel heat recovery technique for PV cooling, fresh and supply air handling: Design and performance assessment

Building integrated photovoltaic (BIPV) technology has emerged as a promising solution for serving electricity and heat demands in buildings. However, PV overheating causes reduced production, increased space cooling load, and stagnation damage. To address overheating and save energy in air conditioning, this study proposed novel single- and dual-inlet ventilation PV curtain wall systems (SVPV and DVPV). In summer, the building exhaust is introduced into the channel to strengthen PV cooling, while incoming fresh air is used to preheat dew-point air. In winter, warm exhaust within the channel decreases heat loss through the facade and then raises the fresh air intake temperature. Mathematical models were developed for the systems, and a comprehensive performance evaluation criterion (PEC) was defined. Economic analysis was conducted using simple payback (SP) and net present value (NPV) models. Additionally, the impact of ambient temperature and solar radiation on system performance was investigated. The case study demonstrates that SVPV and DVPV reduced annual energy consumption by 957.23 kWh (28.07%) and 910.97 kWh (26.72%), respectively, compared to a conventional non-ventilated system. SVPV slightly outperformed DVPV, with an average PEC of 0.556 and 0.544, respectively. This study provides valuable insights for operational strategies and future large-scale promotion of BIPV applications.