• Analysis on the Influence on Heating and Cooling Loads according to PV Panel Installation Conditions

    태양광 시스템 설치 조건에 따른 하부 음영이 냉난방 부하에 미치는 영향 분석

    In-Seo Jeong, Sang-Hoon Park

    정인서, 박상훈

    Installing photovoltaic (PV) systems on rooftops generates shading beneath the panels, which affects the building’s heating and cooling loads. However, previous studies … + READ MORE
    Installing photovoltaic (PV) systems on rooftops generates shading beneath the panels, which affects the building’s heating and cooling loads. However, previous studies on PV systems have focused predominantly on power generation. Therefore, it is necessary to analyze the impact of shading caused by the PV installation conditions on the heating and cooling loads. In this study, simulations were performed on an educational building in Incheon to analyze how shading, determined by PV installation conditions, affects both loads. The results indicated an inverse relationship between the cooling load and the shading factor, whereas the heating load exhibited no significant correlation. A detailed analysis of the installation conditions revealed that lower panel heights led to greater reductions in the cooling load. Regarding the tilt angle, the cooling load decreased in the low-angle range but increased again as the tilt angle increased. This trend was attributed to the rapid decline in solar altitude during August and September. Furthermore, analyzing these cooling load variations in terms of building energy performance confirmed that the cooling load reduction from shading contributed approximately 5.1%–6.5% to the overall improvement in building energy efficiency. These findings suggest that the cooling load reduction effect can serve as an effective design strategy for meeting Zero Energy Building (ZEB) standards, particularly under site conditions where securing optimal power generation efficiency is restricted. - COLLAPSE
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    30 June 2026
  • Performance Analysis of Vertical Bifacial PV Systems under Different Orientation and Albedo Conditions: Experimental and Simulation Study

    수직 양면형 PV 시스템의 방위 및 알베도 조건에 따른 발전성능 분석: 실험 및 시뮬레이션 기반 연구

    Junwon Jang, Jiwon Kim, Hayoung Kim, Jinhee Kim, Juntae Kim

    장준원, 김지원, 김하영, 김진희, 김준태

    Korea has set a target to reduce greenhouse gas emissions in the building sector by approximately 33% by 2030, compared with 2018 … + READ MORE
    Korea has set a target to reduce greenhouse gas emissions in the building sector by approximately 33% by 2030, compared with 2018 levels. Photovoltaic (PV) systems are among the most representative renewable energy technologies for decarbonization, and their installed capacity has increased rapidly. However, PV systems are typically installed facing south to maximize power generation, which is concentrated around midday. This can create imbalances between power supply and demand, harming grid stability. To distribute power generation more evenly throughout the day, east-west-facing PV systems have become a popular choice. In addition, studies are conducted on the effects of bifaciality, albedo, azimuth, and installation height to improve the power-generation performance of east-west-facing PV systems. Nevertheless, relatively few studies have comprehensively analyzed the combined effects of these variables through experiments and simulations. Therefore, this study analyzes the power-generation characteristics of a vertical bifacial PV system through outdoor experiments under different azimuth and albedo conditions. Based on these results, a PVsyst simulation model was developed to predict the annual energy yield. Finally, the experimental and simulation results were compared and analyzed to evaluate the power generation characteristics. - COLLAPSE
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    30 June 2026
  • Thermal Performance Analysis of a Tracking Concentrating Solar Thermal System for Agricultural Energy Production

    농업에너지 생산을 위한 추적 집광형 태양열 시스템 열 성능 분석

    Seung-Hyeon Cheon, Sang-Hyeok Jeong, Beom-Seon Lee, Byeong-Eun Moon

    천승현, 정상혁, 이범선, 문병은

    This study aims to enhance the use of renewable energy for heating agricultural facilities by developing and evaluating a dual-axis tracking and … + READ MORE
    This study aims to enhance the use of renewable energy for heating agricultural facilities by developing and evaluating a dual-axis tracking and concentrating solar thermal system equipped with a Fresnel lens. To increase concentration efficiency, the Fresnel lens was integrated with a precise dual-axis solar tracking mechanism, and a heat-acquisition and circulation system comprising a copper water block was constructed. Outdoor experiments were conducted to measure the solar irradiance, ambient temperature, inlet and outlet temperatures of the heat-transfer fluid, and the temperature of the thermal storage tank. The thermal performance of the system was assessed at flow rates of 1, 2, and 3 L/min. The results revealed an exponential trend between solar irradiance and collector surface temperature. At a flow rate of 2 L/min, the collector achieved efficiencies ranging from 33.3% to 74.8%, with a maximum of 87.5%, which represents the highest performance among the tested conditions. Subsequently, system performance was evaluated by the time required for the thermal storage tank temperature to increase by 10 °C. At 2 L/min, this temperature increase occurred at 5,820 s and resulted in a system efficiency of 60.6%. These findings indicate the potential of the proposed system for generating hot water in agricultural facilities when operated at a relatively favorable flow rate under the present experimental conditions. Further enhancement of the collector insulation is anticipated to minimize heat loss and improve system performance. - COLLAPSE
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    30 June 2026
  • High-Resolution Performance and Sensitivity Analysis of Bifacial PV by Tilt and Azimuth to Complement ECO2 Resolution Limitations

    ECO2 해상도 한계 보완을 위한 양면형 PV의 설치각･방위 고해상도 성능 및 민감도 분석

    Junyoung Lee, Dongsu Kim, Jongho Yoon, Jaewon Kim, Ruda Lee, Hansol Lim, Kihyung Yu

    이준영, 김동수, 윤종호, 김재원, 이루다, 임한솔, 유기형

    Bifacial photovoltaic (PV) systems have garnered considerable attention for building and urban applications. However, ECO2, the Korean evaluation tool for building energy … + READ MORE
    Bifacial photovoltaic (PV) systems have garnered considerable attention for building and urban applications. However, ECO2, the Korean evaluation tool for building energy performance, currently supports only conventional monofacial PV and does not provide a dedicated model for bifacial PV. This limitation is critical as bifacial PV performance depends not only on module tilt and azimuth but also on rear-side irradiance conditions governed by ground albedo and array geometry. In this study, the annual energy yield of bifacial PV systems was quantified under Korean climatic conditions, and region-specific design guidelines were provided based on sensitivity analyses of orientation, albedo, and array configuration. Annual energy production was simulated for 16 representative cities in Korea using pvlib and TMYx weather data derived from observations between 2009 and 2023. Tilt and azimuth were varied from 0° to 90° and 0° to 360°, respectively, at intervals of 5° under albedo conditions of 0.2 and 0.8. For multi-row layouts, module clearance height was varied from 0 m to 3 m at 1 m intervals, and ground coverage ratio (GCR) was varied from 0.4 to 0.8. Increasing albedo from 0.2 to 0.8 increased annual energy production in all cities, with an average gain of 368.33 kWh. The optimal tilt shifted from approximately 30° to 25°, whereas the optimal azimuth remained near south-facing orientations. The benefits of increasing clearance height became marginal beyond approximately 1 m, whereas increasing GCR consistently reduced front- and rear-side irradiance. Overall, these results provide high-resolution reference criteria for bifacial PV design under Korean climatic and urban conditions. - COLLAPSE
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    30 June 2026
  • Experimental Analysis of a Double-Pass Air-Based PVT System with Heat Transfer Enhancement Devices

    열전달 향상 장치를 적용한 이중유로 공기식 PVT 시스템의 실험적 성능 분석

    Geonyong An, Hyeonseok Jeong, Kwangam Moon, Byeonghwa An, Hwiung Choi

    안건용, 정현석, 문광암, 안병화, 최휘웅

    An air-based photovoltaic/thermal (PVT) system is a device that converts solar radiation into useful thermal energy and electricity. However, air-based PVT systems … + READ MORE
    An air-based photovoltaic/thermal (PVT) system is a device that converts solar radiation into useful thermal energy and electricity. However, air-based PVT systems are characterized by low thermal performance, and numerous studies have been conducted to enhance their efficiency using fins, obstacles, and modifications to flow channel configurations. In this study, experiments were conducted to analyze the performance of a system integrated with a heat transfer enhancement device, composed of fins and obstacles, in the lower channel of a double-pass air-based PVT system. The experiments were performed under three distinct air flow rate conditions, each tested over three separate days, from 9:00 a.m. to 4:00 p.m. The results indicated that under high flow rate conditions, indicators such as thermal output, power output, and net energy efficiency were generally the highest. A comparison of daily energy output, considering the thermal output, power output, and fan power consumption, revealed that the highest daily energy output was achieved under the highest flow rate condition. Nevertheless, when only power output and fan power consumption were considered, the medium flow rate condition showed the highest values. Therefore, future research should employ numerical modeling to identify the optimal flow rate for system performance and conduct further performance evaluation studies accordingly. - COLLAPSE
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    30 June 2026
  • Effects of EV Charging Operation Types on Energy Self-Sufficiency Rate and Electricity Cost in Building PV–EV Systems

    건물 PV-EV 시스템에서 전기차 충전 운영 유형이 에너지 자립률 및 전기요금에 미치는 영향

    Ji-Young Eum, Gyeong-Seok Choi

    엄지영, 최경석

    As urban carbon-neutrality policies accelerate the deployment of both electric vehicles (EVs) and zero-energy buildings (ZEBs), the interaction between building photovoltaic (PV) … + READ MORE
    As urban carbon-neutrality policies accelerate the deployment of both electric vehicles (EVs) and zero-energy buildings (ZEBs), the interaction between building photovoltaic (PV) systems and EV charging infrastructure has garnered considerable interest. This interaction is critical because EV charging operation structures must balance economic incentives for stakeholders with grid stability under high PV penetration. However, the current ZEB certification framework excludes EV charging loads from building energy calculations, and EV charging facilities are metered separately from building loads. This configuration leads to a discrepancy between actual power consumption and ZEB-based self-sufficiency assessments. In addition, the existing time-of-use tariff structure applies on-peak rates during daytime hours that coincide with peak PV generation, limiting economic incentives for direct PV utilization in EV charging. This study classifies EV charging operation types into Separated (Type 1), Integrated (Type 2), and Individual (Type 3) based on stakeholder structure and tariff application. The effect of each mode on energy self-sufficiency and electricity costs is evaluated considering a virtual office building as an illustrative case. Plug loads and EV charging loads are included in total energy consumption, and the operation types are compared based on summer weekday average-load profiles. The results show that the energy self-sufficiency rate differs by operation type owing to differences in the total load boundary applied. In terms of electricity cost allocation, charging costs are distributed across multiple stakeholders in the Separated type, whereas the Integrated type enables direct utilization of daytime PV generation for EV charging. Overall, EV charging operation structures affect both energy self-sufficiency assessment and electricity cost allocation, highlighting the need for coordinated policy design between ZEB certification and EV charging frameworks. - COLLAPSE
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    30 June 2026
  • Evaluation of Multi-Zone DCV System in a Residential Building Under Occupancy Scenarios

    공동주택 재실 시나리오에 따른 각실제어 DCV 시스템 평가

    Hanung Jeong, Kyungmo Kang

    정한웅, 강경모

    The construction of zero-energy buildings (ZEB) is a key strategy for achieving Korea’s 2050 carbon neutrality goal. Heat recovery ventilators (HRVs) play … + READ MORE
    The construction of zero-energy buildings (ZEB) is a key strategy for achieving Korea’s 2050 carbon neutrality goal. Heat recovery ventilators (HRVs) play a critical role in ZEB by supplying outdoor air with minimal energy loss. However, conventional HRVs operate at a constant air volume (CAV) regardless of occupancy, which often results in over-ventilation in unoccupied rooms and insufficient ventilation in occupied rooms. This study applied a CO2-based multi-zone demand-controlled ventilation (DCV) system to a full-scale residential test bed to address this limitation. The DCV system independently controlled the airflow to each room using motorized dampers based on the measured CO2 concentration. Three occupant scenarios were tested and compared with a CAV reference set at the legal minimum ventilation rate of 0.5 ACH. The DCV system maintained indoor CO2 concentrations below 1,500 ppm in all scenarios. In bedroom-centered scenarios (Cases 1 and 2), the DCV consumed fan power comparable to that of CAV while distributing airflow according to room-specific demand. In the living-room-centered scenario (Case 3), the DCV reduced fan power consumption by approximately 37% compared to CAV while maintaining an acceptable indoor air quality. These results indicate that CO2-based multi-zone DCV is an effective ventilation strategy for residential buildings, where the occupant distribution varies throughout the day. - COLLAPSE
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    30 June 2026
  • Empirical Validation of the Risk Prioritization Model of Photovoltaic Systems

    태양광 발전 시스템의 위험 우선순위 모델의 실증 분석

    Jinho Choi, Wonwook Oh

    최진호, 오원욱

    In this study, the applicability of the Risk Priority Number (RPN) approach to maintenance prioritization in photovoltaic (PV) systems was investigated using … + READ MORE
    In this study, the applicability of the Risk Priority Number (RPN) approach to maintenance prioritization in photovoltaic (PV) systems was investigated using field data from 200 public PV plants in Jincheon-gun, Republic of Korea. Visual inspections, current–voltage (I–V) measurements, and inverter fault histories were analyzed to reassess the system conditions and recalculate RPN values under real operating environments. To better reflect field characteristics, occurrence scores were determined by incorporating both literature-based estimates and actual fault recurrences derived from operational records. Among the 192 analyzable systems, 130 were classified as abnormal and 62 as normal according to I–V diagnostics; eight sites were excluded owing to measurement limitations. The recalculated RPN values showed a clear separation between normal (1–10) and abnormal systems (40–270), with a median value of 84 for the latter. On the basis of predefined risk thresholds, 40 systems were classified as requiring priority inspection, 27 as high-risk, and four as critical, indicating that a considerable portion of the portfolio demands immediate or near-term maintenance actions. A detailed examination of high-risk systems revealed that electrical faults, combined with repeated fault occurrences, played a decisive role in elevating the risk levels. In particular, bypass diode failures, hotspots, and combiner box or string faults were frequently observed in the upper risk tiers, often accompanied by degradation-related phenomena such as aging and shading-induced mismatch. These findings suggest that not all frequently observed defects contribute equally to operational risk and that fault recurrence and electrical impact should be jointly considered in maintenance prioritization. The results confirm that the RPN, when calibrated with field-acquired data, can serve as a practical tool for identifying high-risk PV systems and supporting maintenance decision-making in large-scale public PV portfolios. The proposed approach enables the systematic prioritization of inspection and repair activities based on actual operational behavior rather than solely on predefined failure assumptions. - COLLAPSE
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    30 June 2026
  • A Literature Review on the Application of Physical AI Robotics for Zero-Energy Building Performance Gap

    제로에너지건물 성능 격차 해소를 위한 Physical AI Robotics 활용 문헌 고찰

    Jongwon Lee

    이종원

    Zero-energy buildings (ZEBs) exhibit energy performance gaps (EPGs) of +14–+30% between design predictions and actual operations. This study reviewed 27 publications (19 … + READ MORE
    Zero-energy buildings (ZEBs) exhibit energy performance gaps (EPGs) of +14–+30% between design predictions and actual operations. This study reviewed 27 publications (19 peer-reviewed articles and eight technical/industrial reports, 2022–2025) across three domains, physical AI robotics, physics-informed neural networks (PINNs), and building digital twins, to analyze the applicability of emerging physical AI technologies to ZEB performance gap closure. Existing reviews on physics-informed machine learning (PIML) focus on methodological taxonomy without addressing robotics or ZEB performance gaps, whereas ZEB digital twin studies rely on fixed Internet of Things (IoT) sensors without autonomous robotics and BIM-robot integration studies are limited to indoor environment monitoring without energy optimization linkages. This review reveals that no prior study has integrated these domains within a unified ZEB performance management framework. Based on the review findings, a five-stage closed-loop framework, zero energy building-physical AI robotics (ZEB-PAR), is derived: Perceive, Diagnose, Update, Optimize, and Verify. Technology readiness level (TRL) analysis revealed an asymmetry between the Perceive–Verify axis (mean TRL 7) and the Diagnose–Optimize axis (mean TRL 5), indicating that robotic data collection and re-inspection are nearly deployment-ready, whereas physics-informed AI and LLM-based optimization require further building-domain adaptation. - COLLAPSE
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    30 June 2026
  • Power Generation Performance Analysis of West Oriented Bifacial PV Systems on Gable Roofs under Different Installation

    박공지붕에 설치된 서향 양면형 PV 시스템의 설치 조건에 따른 발전 성능 분석

    Hayoung Kim, Junwon Jang, Jinhee Kim, Juntae Kim

    김하영, 장준원, 김진희, 김준태

    The global deployment of photovoltaic (PV) systems has accelerated to meet carbon neutrality goals by 2050. However, PV systems are strongly influenced … + READ MORE
    The global deployment of photovoltaic (PV) systems has accelerated to meet carbon neutrality goals by 2050. However, PV systems are strongly influenced by environmental factors such as solar irradiance and ambient temperature, resulting in variability in power generation, which may affect grid stability as PV penetration increases. In Korea, most PV systems are installed facing south to maximize energy yield, resulting in a concentration of power generation during the midday hours. To mitigate this temporal concentration, east–west-oriented PV systems have received increased attention. In building applications, PV modules are frequently installed on the same slope as gable roofs to maintain architectural aesthetics. However, most previous studies have focused on east–west PV systems on flat roofs, with limited experimental studies on bifacial PV systems installed on gable roofs. Therefore, this study experimentally investigated the performance characteristics of a west-oriented bifacial PV system installed on a gable roof using outdoor measurements. Roof albedo, module spacing, and module–roof distance were considered installation parameters. To evaluate the effects of these parameters, the front and rear plane-of-array irradiances and module performance were measured. The results indicate that roof albedo and module–roof distance are the dominant factors affecting the bifacial PV performance, whereas module spacing has a relatively minor influence. Increasing the module–roof distance also enhanced rear-side irradiance during the morning and afternoon periods, suggesting the potential for the temporal distribution of PV power generation. - COLLAPSE
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    30 June 2026
  • Thermal Performance and Surface Condensation Resistance by Design Factors Considering Thermal Bridge in Double-Window System with Insulating Glass Units of Apartment Buildings

    공동주택 복층유리 이중창의 열교 부위를 고려한 설계 요소별 단열 및 결로방지 성능 개선 효과

    JaeRim Kim, Jiwon Bae, Jaehan Lim

    김재림, 배지원, 임재한

    Double-glazed windows with polyvinyl chloride (PVC) frames, which are widely used in residential buildings in South Korea, exhibit low thermal transmittance because … + READ MORE
    Double-glazed windows with polyvinyl chloride (PVC) frames, which are widely used in residential buildings in South Korea, exhibit low thermal transmittance because of the material properties of PVC. However, metal reinforcements are typically inserted within the frames to ensure structural stability. Owing to their high thermal conductivity, these metal reinforcements can act as thermal bridges within the frame, thereby providing preferential heat transfer paths through the window assembly and increasing the system’s overall thermal transmittance (U-value). In addition, the structural deformation of the frame or microgaps at the joints can induce air leakage, resulting in additional heat loss owing to infiltration. To mitigate these effects, air-sealing materials are commonly used to improve the airtightness of window-frame joints. In this study, the thermal performance of double-glazed PVC windows in residential buildings was quantitatively evaluated by considering the heat transfer characteristics of thermal bridge regions. Particularly, the effects of structural reinforcements and air-sealing materials on thermal performance were analyzed. Numerical simulations were conducted to investigate variations in the thermal transmittance of the window system based on the type of glazing unit, material and configuration of internal reinforcements, and the presence of air-sealing materials. The simulation results indicated that the use of low-E glazing and insulated reinforcements resulted in significant improvements in the thermal performance. In addition, the application of air-sealing materials contributes to the reduction in heat loss. - COLLAPSE
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    30 June 2026
  • Energy Performance Analysis of Air-Based BIPVT System Using Building Space

    건축물 공간을 활용한 공기식 BIPVT 시스템의 에너지 성능 분석

    Suho Oh, Youngjin Choi, Sanghee Kim

    오수호, 최영진, 김상희

    Efforts are continuing to reduce carbon emissions in various fields of society with the goal of becoming carbon neutral by 2050. Various … + READ MORE
    Efforts are continuing to reduce carbon emissions in various fields of society with the goal of becoming carbon neutral by 2050. Various studies have been conducted in the construction field to enhance the energy efficiency of buildings through the active introduction and utilization of new and renewable energy. Building-integrated photovoltaic thermal (BIPVT) systems are technologies that can be applied instead of building exterior materials and can generate heat and electrical energy from solar energy. Research has already been conducted on the advantages of BIPVT systems in terms of energy production compared to conventional building-integrated photovoltaic (BIPV) systems, which can only produce electrical energy. However, there have been insufficient studies comparing the performances of both systems simultaneously through experiments under the same weather conditions. In this study, an experimental model of a BIPV system with the similar structure as an air-based BIPVT system experimental model was produced with a new structure that can utilize space itself as a heat recovery device. Subsequently, the experiment was conducted simultaneously, and the thermal and electrical performance of the winter air-based BIPVT system was quantitatively evaluated by comparing it that of the BIPV system. - COLLAPSE
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    30 June 2026
  • Multifunctional Ga2O3 Protective Layer for Enhanced Underwater Silicon Solar Cells

    수중 실리콘 태양전지의 효율 향상을 위한 다기능 Ga2O3 보호층

    Seongjin Ko, Seojun Jeon, Yebean Cho, Seunghee Cho, Barno Md Arifur Rahman, Mooyoung Choi, Joondong Kim

    고성진, 전서준, 조예빈, 조승희, Md Arifur RahmanBarno, 최무영, 김준동

    Si solar cells operated in underwater environments suffer from substantial optical reflection losses and performance degradation due to interfacial instability and thermal … + READ MORE
    Si solar cells operated in underwater environments suffer from substantial optical reflection losses and performance degradation due to interfacial instability and thermal effects. This study introduces a multifunctional gallium oxide (Ga2O3) interfacial layer that enhances optical coupling and interfacial robustness simultaneously. The Ga2O3 layer (n ≈ 1.8–1.9) enables step-index matching between water (n ≈ 1.33) and silicon (n ≈ 3.5), thereby mitigating reflection losses. In addition, its wide bandgap (≈ 4.8 eV) effectively blocks high-energy ultraviolet (UV) radiation, thereby suppressing photo-induced degradation during underwater operation. The amorphous Ga2O3 film, which is synthesized via a low-power sputtering process. To evaluate its efficacy, the optical reflectance and photovoltaic performances of the fabricated devices were systematically characterized under simulated underwater conditions. The sputtered film contributes to an improved interfacial quality and serves as a physical barrier against moisture penetration. With an optimized thickness of 20 nm, the Ga2O3-coated device achieved a power conversion efficiency of 20.7% underwater, corresponding to an improvement of 8.4% compared with conventional Si reference devices (19.1%) tested under identical underwater conditions. These findings demonstrate a practical approach to developing high-performance and reliable underwater photovoltaic systems. - COLLAPSE
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    30 June 2026
  • Empirical Validation of a Risk Prioritization Model Based on Real Failure Data and Its Application to Safety Management in Photovoltaic Systems

    고장 데이터 기반 태양광 발전 시스템의 위험 우선순위 산정 모델 개발 및 실증 연구

    Sungho Park, Jinho Choi, Sungchul Hong

    박성호, 최진호, 홍성철

    The field-applicability of a risk priority number (RPN)-based riskscreening model for public photovoltaic (PV) facilities was evaluated using actual failure and diagnostic … + READ MORE
    The field-applicability of a risk priority number (RPN)-based riskscreening model for public photovoltaic (PV) facilities was evaluated using actual failure and diagnostic data from Jincheon-gun, Korea. Within the conventional failure mode and effects analysis framework, the criteria for severity, occurrence, and detection were redefined to reflect domestic operation and maintenance (O&M) conditions for distributed public PV plants, including remotemonitoring alarms, I-V curve diagnostic, and field inspection practices. Among 100 public PV facilities, 97 with valid I-V measurements were considered in the analysis. Actual fault status was defined using I-V diagnostic results, and monitoring alarm records were preprocessed to exclude non-fault events related to sunrise, sunset, low irradiance, and normal start-up or shutdown . The calculated basic RPN clearly distinguished normal and abnormal facilities. The strongest correlation was observed between the basic RPN and I-V based fault existence (Pearson’s r = 0.902), indicating that the proposed RPN provides significant explanatory power for identifying faulty facilities. The basic RPN also displayed moderate positive correlations with relative performance loss and filtered failure frequency, whereas its correlation with cumulative downtime was weak. This suggests that, downtime is additionally influenced by maintenance response, spare-part availability, site accessibility, and management practices. Overall, the proposed RPN represents an effective primary risk-based screening tool for prioritizing detailed inspection and maintenance in public PV portfolios, rather than a standalone predictor of downtime or fault severity. This work further provides supplementary decision rules that distinguish safety, availability, performance, and structural/environmental risks, supporting O&M decision-making. - COLLAPSE
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    30 June 2026
  • Experimental Analysis of the Thermal Performance of a Green Remodeling Window System Using Suspended-film Multi-Cavity Glazing

    필름 삽입형 다중 공기층 유리 적용 그린리모델링 창호 시스템의 열적 성능 실험 분석

    Seojin Lim, Kyungjoo Cho

    임서진, 조경주

    Multilayer glazing is widely applied to improve the thermal performance of windows. However, its application to existing buildings is hampered by practical … + READ MORE
    Multilayer glazing is widely applied to improve the thermal performance of windows. However, its application to existing buildings is hampered by practical issues such as increased weight. To address these problems, this study established a green remodeling (GR) window system leveraging film-inserted triple glazing and experimentally evaluated its applicability. First, to examine whether the insulation performance of existing double glazing could be improved to the current standard, the thermal transmittance of the GR window system was analyzed using WINDOW 7.8. The simulation results indicated that the U-value decreased from 2.36 W/m2·K for the double-glazing system to 1.60 W/m2·K for the GR window system. The ECO2-OD program was used to determine the decrease in the energy demand of an existing building after applying the GR window system. The annual heating energy demand was reduced by 13% compared with that of a building featuring conventional double-glazed windows. For the full-scale experiment, two laboratories were constructed under identical conditions, one equipped with conventional double-glazed windows and the other featuring the GR window system. Heating was performed for 8 h under identical conditions using heaters, and measurements were recorded over three days using surface temperature sensors and energy-consumption loggers. The interior glass surface temperature of the GR window system was, on average, 2.32 K higher than that of the double-glazing system, while the exterior surface temperature was 1.6 K lower. Compared with the conventional double-glazing system, the laboratory with the GR window system exhibited an average reduction of approximately 11.05% in the heating energy consumption. - COLLAPSE
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    30 June 2026
  • Installation Cost Analysis of BIPV for Economic Feasibility Assessment Based on Reference Office Building Models

    업무시설 표준건축모델 기반 BIPV 경제성 평가를 위한 설치 비용 분석

    JungHyun Lee, Jin-Young Kim, JaeSeok Lee, SeoungMoon Lee, JiWook Lee, Jihye Gwak, KyungSun Lee

    이정현, 김진영, 이재석, 이승문, 이지욱, 곽지혜, 이경선

    Building-integrated photovoltaics (BIPV) has attracted increasing attention owing to its ability to integrate electricity generation with building-envelope functions. However, there remains no … + READ MORE
    Building-integrated photovoltaics (BIPV) has attracted increasing attention owing to its ability to integrate electricity generation with building-envelope functions. However, there remains no standardized framework for assessing their cost and economic feasibility in office buildings. This study analyzes the installation cost and long-term economic feasibility of façade- and rooftop-type BIPV systems in medium- and high-rise office building models using a cost-estimation program and PVsyst simulation. The results indicate that, in both cases, the 25-year cumulative electricity cost-saving benefits of façade- and rooftop-type BIPV systems largely offset the additional costs of conventional glass curtain walls. In particular, façade-type BIPV has greater economic potential as a building-envelope component when the replacement of conventional exterior materials is considered. These findings highlight that BIPV should be evaluated not only as a power-generation system, but also as a building-envelope component that replaces conventional cladding while generating electricity. - COLLAPSE
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    30 June 2026
  • Performance Evaluation of Temperature Distribution Uniformity in AHU Duct Using Static Airmixer

    정적 공기 혼합장치를 이용한 AHU 덕트 내 온도 분포 균일화 성능 평가

    Junwoo Lee, Hanung Jeong, minjae Jeong, Kyungmo Kang

    이준우, 정한웅, 정민재, 강경모

    Energy efficiency in HVAC systems has become increasingly significant given the growing demand for carbon reduction. In air-handling units (AHU), the complete … + READ MORE
    Energy efficiency in HVAC systems has become increasingly significant given the growing demand for carbon reduction. In air-handling units (AHU), the complete mixing of Return Air (RA) and Outdoor Air (OA) leads to temperature nonuniformity, which may cause operational issues such as coil freezing, control instability, and energy loss. This study experimentally evaluated the performance of static air-mixing devices in a full-scale square duct (1 m × 1 m) under realistic AHU conditions. Three cases were considered: Straightener, Baseline louver mixer, and Orthogonal pattern louver mixer. Mixing effectiveness was assessed using a statistical approach based on temperature distribution, and the pressure drop and mixer efficiency index were used to evaluate the overall performance. The results indicated that the baseline Louver mixer achieved the highest mixing effectiveness (84 – 87%) with a moderate pressure drop (14.7 Pa), whereas the Orthogonal-pattern Louver mixer showed a lower mixing effectiveness (53 – 68%) with a higher pressure drop (34.54 Pa). The Straightener case exhibited limited mixing performance with a negligible pressure drop. These findings indicate that both mixing effectiveness and pressure drop must be considered when evaluating air-mixing devices. This study highlights the importance of performance assessment under realistic operating conditions to improve the energy efficiency of AHU systems. - COLLAPSE
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    30 June 2026
  • A Feasibility Study on Applying Large Language Model Techniques to Grey-Box Modeling for Model Predictive Control

    모델기반 예측제어를 위한 Grey-box 모델링의 LLM 기법 적용 가능성 검토 연구

    Taehun Yeo, Jeonghun Seo, Chanhyuk Mo, Jaewan Joe

    여태훈, 서정훈, 모찬혁, 조재완

    This study investigates the applicability of large language model (LLM) assistance to control-oriented grey box thermal modeling for future model predictive control … + READ MORE
    This study investigates the applicability of large language model (LLM) assistance to control-oriented grey box thermal modeling for future model predictive control (MPC) applications. Three modeling methods are compared under identical measured data conditions comprising a hand-coded RC grey box, an AI-generated RC grey box, and an AI-generated ANN black box. The experiments used measured sensor data obtained at 15 min intervals from four building zones and considered the official L1-L4 information levels. The performance was evaluated using the root mean squared error (RMSE) and the coefficient of variation of the root mean square (CVRMSE) for both one-step prediction and 24-h recursive rollout prediction. The results showed that the performance of the AI-generated RC grey box was more consistent across zones and information levels than the AI-generated ANN black box. Meanwhile, the artificial neural network (ANN) remained competitive in some cases but showed larger variability. These findings indicate that LLM assistance can support structured and reproducible grey-box workflow development without the need to replace conventional engineering modeling. - COLLAPSE
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    30 June 2026
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Journal Informaiton Journal of the Korean Solar Energy Society Journal of the Korean Solar Energy Society
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