Energies

30 pages, 7291 KB

Open AccessArticle

Energy Criteria in Adaptive Reuse Decision-Making: A Hybrid DEMATEL-ANP Model for Selecting New Uses of a Historic Building in Poland

by Elżbieta Radziszewska-Zielina, Grzegorz Śladowski, Bartłomiej Szewczyk, Małgorzata Fedorczak-Cisak, Alicja Kowalska-Koczwara, Tadeusz Tatara and Krzysztof Barnaś

Energies 2025, 18(18), 5020; https://doi.org/10.3390/en18185020 (registering DOI) - 21 Sep 2025

Abstract

Historic buildings make up a significant proportion of the existing building stock. Most are characterised by poor technical condition and high energy demand. In Poland, many historic buildings are still in use today, but it is also common to find these buildings subjected [...] Read more.

Historic buildings make up a significant proportion of the existing building stock. Most are characterised by poor technical condition and high energy demand. In Poland, many historic buildings are still in use today, but it is also common to find these buildings subjected to adaptive reuse. Adaptive reuse, often combined with modernisation, is problematic, especially in terms of finding a use that is optimal in the light of use-specific decision criteria. In previous studies, the authors used and developed the potential for the modelling and structural analysis of decision-making problems for the selection of new uses for historic buildings. In this paper, we present a test of this methodology on a Polish historic building. To further the application of our approach in sustainability-focused contexts, we performed the analysis using criteria focused on environmental and energy performance, in addition to other established criteria. In our study, the highest ranking use was a kindergarten, which scored 18% higher than the second-ranked alternative and over 90% higher than the lowest-ranked alternative. Full article

(This article belongs to the Special Issue Green Innovation and Sustainable Energy Transition: Opportunities and Challenges)

► Show Figures

Figure 1

18 pages, 3792 KB

Open AccessArticle

Achieving Power-Noise Balance in Wind Farms by Fine-Tuning the Layout with Reinforcement Learning

by Guangxing Guo, Weijun Zhu, Ziliang Zhang, Wenzhong Shen and Zhe Chen

Energies 2025, 18(18), 5019; https://doi.org/10.3390/en18185019 (registering DOI) - 21 Sep 2025

Abstract

Wind farms situated in proximity to residential areas present environmental challenges, primarily due to noise emissions. Rectangular and parallelogram layouts are commonly employed in current wind farm designs owing to their simplicity and visual appeal. However, such configurations often experience significant power loss [...] Read more.

Wind farms situated in proximity to residential areas present environmental challenges, primarily due to noise emissions. Rectangular and parallelogram layouts are commonly employed in current wind farm designs owing to their simplicity and visual appeal. However, such configurations often experience significant power loss under certain wind directions because of intense wake interactions. This paper proposes a layout fine-tuning strategy for low-noise wind farm design. Within a reinforcement learning framework integrated with an engineering wake model and a noise propagation model, the positions of two turbines (controlled by two variables) are optimized. The noise propagation model was validated for idealized long-range sound propagation over flat terrain with acoustically soft surfaces. A case study was conducted on a 12-turbine wind farm located on a flat plain in China, with a noise threshold of 45 dB(A) used to assess the noise impact area. Optimization results demonstrate that the proposed method achieves a balance between power output and noise reduction compared to the original regular layout: Annual Energy Production (AEP) increased slightly by 0.16%, while the noise impact area was reduced by 6.0%. Although these improvements appear modest, the potential of the proposed methodology warrants further investigation. Full article

(This article belongs to the Special Issue Advancements in Wind Farm Design and Optimization)

► Show Figures

Figure 1

40 pages, 6823 KB

Open AccessArticle

Strategic Planning for Power System Decarbonization Using Mixed-Integer Linear Programming and the William Newman Model

by Jairo Mateo Valdez Castro and Alexander Aguila Téllez

Energies 2025, 18(18), 5018; https://doi.org/10.3390/en18185018 (registering DOI) - 21 Sep 2025

Abstract

This paper proposes a comprehensive framework for strategic power system decarbonization planning that integrates the William Newman method (diagnosis–options–forecast–decision) with a multi-objective Mixed-Integer Linear Programming (MILP) model. The approach simultaneously minimizes (i) generation cost, (ii) expected cost of energy not supplied (Value of [...] Read more.

This paper proposes a comprehensive framework for strategic power system decarbonization planning that integrates the William Newman method (diagnosis–options–forecast–decision) with a multi-objective Mixed-Integer Linear Programming (MILP) model. The approach simultaneously minimizes (i) generation cost, (ii) expected cost of energy not supplied (Value of Lost Load, VoLL), (iii) demand response cost, and (iv) CO₂ emissions, subject to power balance, technical limits, and binary unit commitment decisions. The methodology is validated on the IEEE RTS 24-bus system with increasing demand profiles and representative cost and emission parameters by technology. Three transition pathways are analyzed: baseline scenario (no environmental restrictions), gradual transition (−50% target in 20 years), and accelerated transition (−75% target in 10 years). In the baseline case, the oil- and coal-dominated mix concentrates emissions (≈14 ktCO₂ and ≈12 ktCO₂, respectively). Under gradual transition, progressive substitution with wind and hydro reduces emissions by 15.38%, falling short of the target, showing that renewable expansion alone is insufficient without storage and demand-side management. In the accelerated transition, the model achieves −75% by year 10 while maintaining supply, with a cost–emissions trade-off highly sensitive to the carbon price. Results demonstrate that decarbonization is technically feasible and economically manageable when three enablers are combined: higher renewable penetration, storage capacity, and policy instruments that both accelerate fossil phase-out and valorize demand-side flexibility. The proposed framework is replicable and valuable for outlining realistic, verifiable transition pathways in power system planning. Full article

(This article belongs to the Special Issue Advances and Optimization of Electric Energy System—2nd Edition)

23 pages, 1062 KB

Open AccessReview

Cybersecurity of Smart Grids: Requirements, Threats, and Countermeasures

by Edyta Karolina Szczepaniuk and Hubert Szczepaniuk

Energies 2025, 18(18), 5017; https://doi.org/10.3390/en18185017 (registering DOI) - 21 Sep 2025

Abstract

Cybersecurity is a key factor influencing the development of the smart grid paradigm. The integration of information and communication technologies into energy networks introduces new cybersecurity requirements, vulnerabilities, and threats. Typical countermeasures and security measures require optimization and customization for implementation in a [...] Read more.

Cybersecurity is a key factor influencing the development of the smart grid paradigm. The integration of information and communication technologies into energy networks introduces new cybersecurity requirements, vulnerabilities, and threats. Typical countermeasures and security measures require optimization and customization for implementation in a distributed and heterogeneous smart grid environment. In this paper, we propose a holistic approach to smart grid cybersecurity by considering information security attributes at the level of requirements, threats, and countermeasures analysis. The results of the conducted review enabled us to develop a holistic cybersecurity framework for smart grids, while also analyzing the challenges and barriers related to security measures, as well as the possibilities for their mitigation. Full article

(This article belongs to the Section A1: Smart Grids and Microgrids)

► Show Figures

Figure 1

28 pages, 1408 KB

Open AccessReview

A Rapid Review of Hygrothermal Performance Metrics for Innovative Materials in Building Envelope Retrofits

by Robin Hilbrecht, Cynthia A. Cruickshank, Christopher Baldwin and Nicholas Scharf

Energies 2025, 18(18), 5016; https://doi.org/10.3390/en18185016 (registering DOI) - 21 Sep 2025

Abstract

With government, industry, and public pressure to decarbonize the building sector through reducing embodied and operational emissions, there have been a wide range of innovative materials used in building envelope retrofits. Although these innovative materials, such as super insulating materials, bio-based insulation, and [...] Read more.

With government, industry, and public pressure to decarbonize the building sector through reducing embodied and operational emissions, there have been a wide range of innovative materials used in building envelope retrofits. Although these innovative materials, such as super insulating materials, bio-based insulation, and many others, are assessed on thermal performance and code requirements before use in retrofits, there is no unified standard assessment metric for hygrothermal performance of innovative materials in building envelope retrofits. This paper performs a rapid review of the available literature from January 2013 to March 2025 on hygrothermal performance assessment metrics used in retrofits. Using rapid review methods to search for records in Scopus, Web of Science, and Google Scholar, fifty-nine publications were selected for bibliometric and qualitative analysis. Most selected publications include discussions and analysis of relative humidity in the wall assembly post retrofit, moisture content, and mould index within the envelope. There is a research gap in publications considering hygrothermal damage functions such as freeze–thaw index, relative humidity and temperature (RHT) index, or condensation prediction. There is also a research gap in country and climate studies and analyses of in situ retrofits with innovative materials, and occupant comfort post retrofit. Full article

(This article belongs to the Special Issue Sustainable Built Environment: Energy Efficiency Technologies, Performance Evaluation and Indoor Environment Quality)

18 pages, 6081 KB

Open AccessArticle

Novel Design of Conical-Shaped Wireless Charger for Unmanned Aerial Vehicles

by Ashraf Ali, Omar Saraereh and Andrew Ware

Energies 2025, 18(18), 5015; https://doi.org/10.3390/en18185015 (registering DOI) - 21 Sep 2025

Abstract

This work presents a novel wireless charging system for unmanned aerial vehicles (UAVs), which employs conical-shaped coils that also function as landing gear. By integrating electromagnetic simulation, circuit modeling, and system-level evaluation, we introduce an innovative coil design that enhances wireless power transfer [...] Read more.

This work presents a novel wireless charging system for unmanned aerial vehicles (UAVs), which employs conical-shaped coils that also function as landing gear. By integrating electromagnetic simulation, circuit modeling, and system-level evaluation, we introduce an innovative coil design that enhances wireless power transfer (WPT) efficiency while reducing misalignment sensitivity. The conical geometry naturally facilitates mechanical alignment upon drone landing, thereby improving inductive coupling. High-frequency simulations were carried out to optimize the coil parameters and evaluate the link efficiency at 6.78 MHz, an ISM-designated frequency. Our experimental testing confirmed that the proposed conical coil achieves high power transfer efficiency (up to 94%) under practical conditions, validating the effectiveness of the geometry. The characteristics of the designed coil make it highly suitable for use with Class EF amplifiers operating in the same frequency range; however, detailed amplifier hardware implementation and efficiency characterization were beyond the scope of this study and are reserved for future work. The results demonstrate the potential of the proposed system for deployment in UAV field applications such as surveillance, delivery, and remote sensing. Full article

(This article belongs to the Special Issue Advances in Design, Operation and Maintenance Technology for Electric Power Equipment)

► Show Figures

Figure 1

14 pages, 4170 KB

Open AccessArticle

Pressure-Dependent Breakdown Voltage in SF6/Epoxy Resin Insulation Systems: Electric Field Enhancement Mechanisms and Interfacial Synergy

by Lin Liu, Qiaogen Zhang, Xiangyang Peng, Xiaoang Li, Zheng Wang and Shihu Yu

Energies 2025, 18(18), 5014; https://doi.org/10.3390/en18185014 (registering DOI) - 21 Sep 2025

Abstract

In SF₆ gas-insulated equipment, solid dielectrics critically degrade insulation performance by reducing the electric field’s ability to withstand gas gaps. To investigate the critical role played by solid dielectric surfaces during the initial phase of gas–solid interface discharge phenomena, this paper experimentally [...] Read more.

In SF₆ gas-insulated equipment, solid dielectrics critically degrade insulation performance by reducing the electric field’s ability to withstand gas gaps. To investigate the critical role played by solid dielectric surfaces during the initial phase of gas–solid interface discharge phenomena, this paper experimentally measures the AC breakdown voltage (U_bd) of both dielectric surface-initiated breakdown (DIBD) and electrode surface-initiated breakdown (EIBD) across eight types of post insulator samples. Tests are conducted in 36 mm SF₆ gas gaps under pressures ranging from 0.1 to 0.4 MPa. Combined with electrostatic field simulations, the results reveal that DIBD requires substantially lower U_bd than EIBD under comparable maximum electric field (E_max) conditions. As gas pressure increases, this difference becomes more pronounced. This phenomenon can be explained by three key mechanisms: First, due to the regulatory effect of dielectric materials and shielding electrodes on the electric field distribution, the high-electric-field zone along the gas–solid interface exhibits a longer effective discharge path compared to that in a pure gas gap. This configuration creates more favorable conditions for discharge initiation and subsequent propagation toward the opposite electrode. Second, microscopic irregularities on the dielectric surface induce stronger local electric field enhancement than comparable features on metallic electrodes. Third, in high-electric-field regions adjacent to the dielectric surface, desorption processes significantly enhance electron multiplication during gas discharge, and this enhancement effect becomes more pronounced as gas pressure increases, further lowering the discharge inception threshold. As a result, discharge initiation at dielectric interfaces requires less stringent electric field conditions compared to breakdown in a gas gap, especially at high gas pressure. This conclusion not only accounts for the saturation behavior in the U_bd-p characteristic of SF₆ gas–solid interface discharges but also explains why surface contaminants/defects disproportionately degrade interfacial insulation performance relative to their impact on gas gaps. Full article

(This article belongs to the Special Issue Recent Progress, Challenges and Outlooks of Insulation System in HVDC: 2nd Edition)

21 pages, 3104 KB

Open AccessArticle

Advanced Structural Assessment of a Bucked-and-Wedged Configuration for the EU DEMO Tokamak Under a 16.5 T Magnetic Field

by Andrea Chiappa and Corrado Groth

Energies 2025, 18(18), 5013; https://doi.org/10.3390/en18185013 (registering DOI) - 21 Sep 2025

Abstract

The pursuit of compact and efficient fusion energy systems necessitates innovative structural concepts capable of withstanding extreme operational conditions. This study presents a preliminary structural evaluation and stress assessment of a bucked-and-wedged configuration for the EU DEMO tokamak, targeting a peak magnetic field [...] Read more.

The pursuit of compact and efficient fusion energy systems necessitates innovative structural concepts capable of withstanding extreme operational conditions. This study presents a preliminary structural evaluation and stress assessment of a bucked-and-wedged configuration for the EU DEMO tokamak, targeting a peak magnetic field of 16.5 T. The proposed concept leverages mutual wedging of the Toroidal Field (TF) coils and their interaction with the Central Solenoid (CS) to optimize stress distribution in the inner legs, a critical region in high-field fusion reactors. To address the significant tangential forces arising during plasma operation, the design integrates outer inter-coil structures and shear pins to enhance mechanical stability. A hybrid simulation approach—coupling 3D electromagnetic and structural finite element analyses—is employed to assess stress behavior and structural integrity under both in-plane and out-of-plane loading conditions. The results contribute to the optimization study of high-field fusion reactor components and offer insights into viable mechanical design strategies for next-generation nuclear energy systems. Full article

(This article belongs to the Special Issue Advanced Simulations for Nuclear Fusion Energy Systems)

► Show Figures

Figure 1

26 pages, 547 KB

Open AccessReview

Validation Strategies for District Heating Network Models

by Jakub Kuś, Łukasz Mika and Michał Żurawski

Energies 2025, 18(18), 5012; https://doi.org/10.3390/en18185012 (registering DOI) - 21 Sep 2025

Abstract

Due to the complexity of district heating systems, improved novel methods of district heating network (DHN) simulation are still being introduced in the literature. The subject of validation strategies for DHN simulation models emerges as one that has not been thoroughly analyzed before. [...] Read more.

Due to the complexity of district heating systems, improved novel methods of district heating network (DHN) simulation are still being introduced in the literature. The subject of validation strategies for DHN simulation models emerges as one that has not been thoroughly analyzed before. Based on the considered subset of models reported in the literature, a general classification of the validation strategies of DHN models is proposed in this study. The proposed classification is based on two criteria: data and topology used in the validation case studies. This study provides insights into validation strategies for DHN models, their practical implementation and evaluation criteria, and the approaches used in the validation of these models. The standardization of DHN model validation approaches and the possibility to replicate the validation results seem to be limited. It seems that the dissemination of dedicated benchmarks or commonly accepted methodologies featuring evaluation criteria suitable for models’ intended applications could have a positive impact on the thoroughness of future DHN model validation and the replicability of validation results. To assist in future research, preliminary validation guidelines are proposed that may serve as a starting point in designing validation case studies for DHN models. Full article

(This article belongs to the Section G: Energy and Buildings)

► Show Figures

Figure 1

20 pages, 6872 KB

Open AccessArticle

Machine Learning-Based Prediction of Dye-Sensitized Solar Cell Efficiency for Manufacturing Process Optimization

by Zoltan Varga, Marek Bobcek, Zsolt Conka and Ervin Racz

Energies 2025, 18(18), 5011; https://doi.org/10.3390/en18185011 (registering DOI) - 21 Sep 2025

Abstract

The dye-sensitized solar cell (DSSC) is a promising candidate, offering an attractive substitute for conventional silicon-based photovoltaic technologies. The performance advantages of the DSSC have led to a surge in research activity reflected in the number of publications over the years. To deliver [...] Read more.

The dye-sensitized solar cell (DSSC) is a promising candidate, offering an attractive substitute for conventional silicon-based photovoltaic technologies. The performance advantages of the DSSC have led to a surge in research activity reflected in the number of publications over the years. To deliver data-driven analysis of DSSC performance, machine learning models have been applied. As a first step, a literature-based database has been developed and after the data preprocesses, Decision Tree (DT), Random Forest (RF), K-Nearest Neighbors (KNN), Support Vector Machine (SVM), xgboost (XGB), and Artificial Neural Network (ANN) algorithms were applied with stratified train-test splits. The performance of the models has been assessed via metrics, and the model interpretability relied on SHAP analysis. Based on the employed metrics and the confusion matrix, DT, RF, and KNN are the most accurate models for predicting DSSC efficiency on the developed dataset. Furthermore, it was revealed that synthesis temperature and the thickness of thin film were identified as the dominant drivers, followed by precursor and dye. Mid-tier contributors were morphological structure, electrolyte concentrations, and the absorption maximum. The results suggest that in optimizing the manufacturing process, targeted tuning of the synthesis temperature, the thickness of thin film, the precursor, and the dye are likely to improve the performance of the device. Therefore, experimental effort should concentrate on these factors. Full article

(This article belongs to the Special Issue Advances in Sustainable Power and Energy Systems: 2nd Edition)

► Show Figures

Figure 1

28 pages, 2938 KB

Open AccessArticle

Boiling and Condensing Two-Phase Frictional Pressure Drop Within Minichannel Tubes—Comparison and New Model Development Based on Experimental Measurements

by Calos Martínez-Lara, Alejandro López-Belchí and Francisco Vera-García

Energies 2025, 18(18), 5010; https://doi.org/10.3390/en18185010 (registering DOI) - 20 Sep 2025

Abstract

This study presents a comprehensive experimental investigation into the frictional pressure drop of two-phase flows—boiling and condensation—in horizontal minichannels, emphasizing its impact on the energy efficiency of vapor compression systems. A total of 3553 data points were obtained using six low-GWP refrigerants (R32, [...] Read more.

This study presents a comprehensive experimental investigation into the frictional pressure drop of two-phase flows—boiling and condensation—in horizontal minichannels, emphasizing its impact on the energy efficiency of vapor compression systems. A total of 3553 data points were obtained using six low-GWP refrigerants (R32, R134a, R290, R410A, R513A, and R1234yf) across a wide range of operating conditions in multiport aluminum tubes with hydraulic diameters of 0.715 mm and 1.16 mm. The dataset covers mass fluxes from 200 to 1230

kg m^{- 2} s^{- 1}

, saturation temperatures between 5 °C and 55 °C, and vapor qualities from 0.05 to 0.95. Results showed a strong dependence of frictional pressure gradient on vapor quality, mass flux, and channel size. Boiling flows generated higher frictional losses than condensation, and high-density refrigerants such as R32 exhibited the largest pressure penalties, which can directly translate into increased compressor power demand. Conversely, higher saturation temperatures were associated with lower frictional losses, highlighting the role of thermophysical properties in improving energy performance. Additionally, an inverse correlation between saturation temperature and frictional pressure gradient was observed, attributed to variations in thermophysical properties such as viscosity and surface tension. Existing correlations from the literature were assessed against the experimental dataset, with notable deviations observed in several cases, particularly for R134a under high-quality conditions. Consequently, a new empirical correlation was developed for predicting the frictional pressure drop in two-phase flow through minichannels. The proposed model, formulated using a power-law regression approach and incorporating dimensionless parameters, achieved better agreement with the experimental data, reducing prediction error to within ±20%, improving the accuracy for the majority of cases. This work provides a robust and validated dataset for the development and benchmarking of predictive models in compact heat exchanger design. By enabling the more precise estimation of two-phase pressure drops in compact heat exchangers, the findings support the design of refrigeration, air-conditioning, and heat pump systems with minimized flow resistance and reduced auxiliary energy consumption. This contributes to lowering compressor workload, improving coefficient of performance (COP), and it ultimately advances the development of next-generation cooling technologies with enhanced energy efficiency. Full article

(This article belongs to the Special Issue Advances in Numerical and Experimental Heat Transfer)

► Show Figures

Figure 1

19 pages, 3138 KB

Open AccessArticle

Solar-Pumped Ce:Nd:YAG Laser Amplifier Design

by Joana Almeida, Bruno D. Tibúrcio, Hugo Costa, Cláudia R. Vistas and Dawei Liang

Energies 2025, 18(18), 5009; https://doi.org/10.3390/en18185009 (registering DOI) - 20 Sep 2025

Abstract

A solar-pumped Ce:Nd:YAG laser amplifier design is proposed to address the challenge of scaling output power in solar-pumped laser oscillators while maintaining high beam quality. The design employs a 1.33 m² flat Fresnel lens with a 2 m focal length as a [...] Read more.

A solar-pumped Ce:Nd:YAG laser amplifier design is proposed to address the challenge of scaling output power in solar-pumped laser oscillators while maintaining high beam quality. The design employs a 1.33 m² flat Fresnel lens with a 2 m focal length as a primary concentrator, which is combined with a secondary homogenizing concentrator, featuring 40 mm × 40 mm input aperture, 200 mm length, and 11.3 mm × 26 mm output aperture, to provide efficient coupling and uniform distribution of solar radiation onto a 2.9 mm thick Ce:Nd:YAG slab with 11.3 mm × 26 mm surface area and two beveled corners. This geometry enables multiple total internal reflections of a 1064 nm TEM₀₀ mode seed laser beam inside the slab, ensuring efficient interaction with the active Ce³⁺ and Nd³⁺ ions in the gain medium. Performed numerical analysis shows that the present approach can deliver a uniform solar pump power density of 2.5 W/mm² to the slab amplifier. This value is 2.05-times higher than the numerically calculated power density incident on the Nd:YAG slab of the previous solar-pumped amplifier that achieved the highest continuous-wave laser gain of 1.64. Furthermore, the optimized slab geometry with 0.44 width-to-height ratio allows the seed laser to undergo 32 internal reflections, extending its optical path length by a factor of 1.45 compared to the earlier design. These numerical achievements, combined with the Ce:Nd:YAG medium’s capacity to deliver nearly 1.57-times more laser power than Nd:YAG, reveal the potential of proposed design to yield a gain enhancement factor of 4.16, making the first solar-pumped Ce:Nd:YAG amplifier a promising solution toward energy-efficient, sustainable solutions for terrestrial and space applications. Full article

(This article belongs to the Special Issue Advances in Photovoltaic/Solar Collectors and Their Potential for an Industrial Decarbonization: 2nd Edition)

23 pages, 2077 KB

Open AccessArticle

Long-Term Performance of Thermal Insulating Composite Systems Based on Water Resistance and Surface Multifunctionality

by Giovanni Borsoi, João L. Parracha, Jéssica D. Bersch, Ana R. Garcia, Amélia Dionísio, Paulina Faria, Rosário Veiga and Inês Flores-Colen

Energies 2025, 18(18), 5008; https://doi.org/10.3390/en18185008 (registering DOI) - 20 Sep 2025

Abstract

External Thermal Insulation Composite Systems (ETICSs) are increasingly applied in both new construction and energy retrofitting, where long-term durability under environmental exposure is critical to preserving thermal efficiency. Moisture ingress represents a key degradation factor, reducing insulation performance and undermining energy savings promoted [...] Read more.

External Thermal Insulation Composite Systems (ETICSs) are increasingly applied in both new construction and energy retrofitting, where long-term durability under environmental exposure is critical to preserving thermal efficiency. Moisture ingress represents a key degradation factor, reducing insulation performance and undermining energy savings promoted by the ETICS. The effectiveness of these systems is strongly influenced by surface protection, which also reflects aesthetic and biological resistance. This study investigates the influence of three commercial protective surface coatings, characterized by hydrophobicity, photocatalytic activity, and resistance to biological growth, on ETICS finishes based on acrylic, natural hydraulic lime (NHL), and silicate binders. An artificial aging protocol was employed to evaluate coating stability and compatibility with the finishing layers. Results show that acrylic-based finishes provided superior durability and protection, while coatings on NHL and silicate substrates exhibited lower performance. Notably, a TiO₂ enriched photocatalytic coating, despite improved self-cleaning potential, demonstrated the least durability. The findings highlight that optimal ETICS protection requires coatings that combine low water absorption, effective drying, and biological resistance, thereby ensuring sustained thermal and energy performance over time. Full article

(This article belongs to the Special Issue Thermal Behaviour, Energy Efficiency in Buildings and Sustainable Construction: 4th Edition)

► Show Figures

Figure 1

52 pages, 1374 KB

Open AccessReview

A Review of Methodologies for Photovoltaic Energy Generation Forecasting in the Building Sector

by Omid Pedram, Ana Soares and Pedro Moura

Energies 2025, 18(18), 5007; https://doi.org/10.3390/en18185007 (registering DOI) - 20 Sep 2025

Abstract

Photovoltaic (PV) systems are swiftly expanding within the building sector, offering significant benefits such as renewable energy integration, yet introducing challenges due to mismatches between local generation and demand. With the increasing availability of data and advanced modeling tools, stakeholders are increasingly motivated [...] Read more.

Photovoltaic (PV) systems are swiftly expanding within the building sector, offering significant benefits such as renewable energy integration, yet introducing challenges due to mismatches between local generation and demand. With the increasing availability of data and advanced modeling tools, stakeholders are increasingly motivated to adopt energy management and optimization techniques, where accurate forecasting of PV generation is essential. While the existing literature provides valuable insights, a comprehensive review of methodologies specifically tailored for the forecast of PV generation in buildings remains scarce. This study aims to address this gap by analyzing the forecasting methods, data requirements, and performance metrics employed, with the primary objective of providing an in-depth review of previous research. The findings highlight the critical role of improving PV energy generation forecasting accuracy in enhancing energy management and optimization for individual buildings. Additionally, the study identifies key challenges and opportunities for future research, such as the limited exploration of localized environmental and operational factors (such as partial shading, dust, and dirt); insufficient data on building-specific PV output patterns; and the need to account for variability in PV generation. By clarifying the current state of PV energy forecasting methodologies, this research lays essential groundwork for future advancements in the field. Full article

(This article belongs to the Special Issue Optimal Planning, Integration and Control of Smart Microgrid Systems with Renewable Energy: 2nd Edition)

16 pages, 3843 KB

Open AccessArticle

Electro-Thermal Analysis of Lithium-Ion Battery Modules Equipped with Thermal Barrier Pad for Urban Air Mobility During Flight Scenarios

by Geesoo Lee

Energies 2025, 18(18), 5006; https://doi.org/10.3390/en18185006 (registering DOI) - 20 Sep 2025

Abstract

This study presents an electro-thermal analysis of high-power lithium-ion battery modules for urban air mobility (UAM) applications, focusing on assessing the operational impact of installing a thermal barrier pad (TBP)—designed for thermal runaway delay—to ensure that the module maintains acceptable performance during normal [...] Read more.

This study presents an electro-thermal analysis of high-power lithium-ion battery modules for urban air mobility (UAM) applications, focusing on assessing the operational impact of installing a thermal barrier pad (TBP)—designed for thermal runaway delay—to ensure that the module maintains acceptable performance during normal operations. An integrated electro-thermal simulation model was developed and validated through single-cell experiments under step-load conditions, showing good agreement with measured voltage and temperature. In the baseline module without a TBP, higher discharge rates resulted in increased heat generation and cell temperatures, with approximately 42.5% of the electrical output dissipated as heat under the 5C condition. When the TBP was applied, the cooling performance of the heat sink decreased, leading to higher module temperatures and increased temperature differences between the cell and the heat sink, particularly as the TBP thickness increased. A simplified UAM flight scenario was simulated to evaluate temperature behavior throughout various operating phases. For the 1.5 mm TBP model, the maximum temperature (75.7 °C) remained within the design limit (80 °C). However, increasing the maximum take-off discharge rate to 6C or higher caused the module to reach its thermal limit or cut-off voltage before mission completion. These results indicate that TBP installation can be applied without unacceptable performance degradation under normal operation, provided that its thickness is optimized by considering cooling performance, thermal safety, and weight/volume constraints in UAM applications. Full article

► Show Figures

Figure 1

21 pages, 3844 KB

Open AccessArticle

Modelling Water Hammer Effects in Rising Pipeline Systems Using the PKP Method and the MOC

by Waldemar Sradomski, Aneta Nycz and Marek Skowroński

Energies 2025, 18(18), 5005; https://doi.org/10.3390/en18185005 (registering DOI) - 20 Sep 2025

Abstract

Water hammer is a critical transient phenomenon in pumping systems, occurring when a sudden change in flow velocity generates pressure waves propagating along the pipeline. This study focuses on the dynamic response of a long rising pipeline subjected to an emergency pump shutdown, [...] Read more.

Water hammer is a critical transient phenomenon in pumping systems, occurring when a sudden change in flow velocity generates pressure waves propagating along the pipeline. This study focuses on the dynamic response of a long rising pipeline subjected to an emergency pump shutdown, with particular emphasis on the sudden release and propagation of hydraulic energy in the form of pressure waves. Such scenarios are typical for mine dewatering and water supply systems with high elevation differences. Two numerical approaches were investigated: the Method of Characteristics (MOC) implemented in TSNet as a reference model, and the Train Analogy Method (PKP) implemented in MATLAB R2024b/Simulink, where the fluid is represented as discrete masses connected by elastic links, enabling the inclusion of pump and motor dynamics. Simulations were performed for two configurations: first–with a check valve installed only at the pump discharge and second–with a check valve at the pump discharge and in the middle of the pipeline. The results demonstrate that both models capture the essential features of water hammer: a sharp initial pressure drop, the formation of transient waves, and pressure oscillations with decreasing amplitude. These oscillations reflect the propagation and gradual dissipation of hydraulic energy stored in the moving fluid, primarily due to frictional and elastic effects within the pipeline. The presence of a check valve accelerates the attenuation of oscillations, effectively reducing the impact of returning waves on the downstream pipeline. The novelty of this study lies in the use of the PKP method to simulate transient flow and energy exchange in long rising pipelines with dynamic pump behavior. The method offers a physically intuitive and modular approach that enables the modelling of local flow phenomena, pressure wave propagation, and system components such as pump–motor inertia and check valves. This makes PKP a valuable tool for investigating complex water hammer scenarios, as it enables the analysis of pressure wave propagation and damping, providing insight into the scale and evolution of energy released during sudden operational incidents, such as an emergency pump shutdown. The close agreement between the PKP and MOC results confirms that the PKP method implemented in Simulink is a reliable tool for predicting transient pressure behavior in hydraulic installations and supports its use for further validation and dynamic system analysis. Full article

(This article belongs to the Section B: Energy and Environment)

► Show Figures

Figure 1

20 pages, 3844 KB

Open AccessArticle

Open-Circuit Fault Detection in a 5-Level Cascaded H-Bridge Inverter Using 1D CNN and LSTM

by Chouaib Djaghloul, Kambiz Tehrani and François Vurpillot

Energies 2025, 18(18), 5004; https://doi.org/10.3390/en18185004 (registering DOI) - 20 Sep 2025

Abstract

It is well known that power converters have the highest failure rate in the energy conversion chain in different industrial applications. This could definitely affect the reliability of the system. The reliability of converters in power conversion systems is crucial, as failures can [...] Read more.

It is well known that power converters have the highest failure rate in the energy conversion chain in different industrial applications. This could definitely affect the reliability of the system. The reliability of converters in power conversion systems is crucial, as failures can lead to critical consequences and damage other system components. Therefore, it is important to predict and detect failures and take corrective actions to prevent them. One of the most common types of failure in power converters is semiconductor failure, which can manifest as an open circuit or a short circuit. This paper focuses on single and double open-circuit switch failures in a 5-level cascaded H-bridge inverter, for which a fast, precise method is required. A data-driven approach is employed here, using the output voltage and voltages across each H-bridge as diagnostic signals. A 1D-CNN LSTM neural network is trained to accurately detect and localize open-circuit faults, providing a reliable, practical solution. Full article

(This article belongs to the Special Issue Advances in Control System for Power Electronics, Microgrids, and Smart Grids)

► Show Figures

Figure 1

14 pages, 1918 KB

Open AccessArticle

An Electrothermal Model of a Heatsink-Less Thermoelectric Generator in a Thermalization State

by Piotr Dziurdzia, Piotr Bratek, Ireneusz Brzozowski and Michał Markiewicz

Energies 2025, 18(18), 5003; https://doi.org/10.3390/en18185003 (registering DOI) - 20 Sep 2025

Abstract

The paper presents the development and experimental verification of an electrothermal model of a heatsink-less thermoelectric generator (TEG) implemented in the LTspice simulator. The model incorporates key physical phenomena, including the Seebeck effect, the Peltier effect, and Joule heating. It also takes into [...] Read more.

The paper presents the development and experimental verification of an electrothermal model of a heatsink-less thermoelectric generator (TEG) implemented in the LTspice simulator. The model incorporates key physical phenomena, including the Seebeck effect, the Peltier effect, and Joule heating. It also takes into account a variable convective thermal resistance to the environment that depends on the temperature of the thermoelectric module’s cold side. The model was calibrated using experimental measurements of the open-circuit Seebeck voltage and the output voltage under resistive load connected to the TEC1-12706-SR thermoelectric module (TEM), under controlled temperature gradients. The model’s accuracy was validated by comparing simulation results with measured output voltages and power generated by the TEG for various load resistances and ambient temperatures. The simulations showed good agreement with the experimental data. The analysis and tests also confirmed the existence of an optimal load resistance that maximizes power transfer from the module, which is consistent with the principle of matching the load to the TEG’s internal resistance. We present the comparison between the theoretical model of a TEG and its physical properties. We used the results of the measurements to tailor the model, so finally we were able to achieve consistency of measurements with experiment within 10–17%. The developed model is a useful tool for rapid design and optimization of energy-harvesting systems using TEGs, enabling the integration of these generators into autonomous IoT systems and wearable electronics, without the need for a traditional heatsink. Full article

► Show Figures

Figure 1

41 pages, 2987 KB

Open AccessReview

Coordinated Optimization of Building Morphological Parameters Under Urban Wind Energy Targets: A Review

by Yingwen Qin and Biao Wang

Energies 2025, 18(18), 5002; https://doi.org/10.3390/en18185002 (registering DOI) - 20 Sep 2025

Abstract

Against the backdrop of global energy crises and accelerated urbanization, urban wind energy has garnered increasing attention through its integration with building environments. This study investigates the synergistic optimization of architectural parameters (including floor layouts, three-dimensional forms, and roof configurations) with wind capture [...] Read more.

Against the backdrop of global energy crises and accelerated urbanization, urban wind energy has garnered increasing attention through its integration with building environments. This study investigates the synergistic optimization of architectural parameters (including floor layouts, three-dimensional forms, and roof configurations) with wind capture efficiency. By employing parameterized design and multi-scale flow field analysis, we systematically examine how architectural morphology modulates wind fields and enhances energy performance. Our key findings reveal the following: spatially arranged floor plans significantly influence wind speed distribution; three-dimensional form openings effectively enhance wind velocity while reducing wind-induced vibration responses; and roof configurations and floor layouts demonstrate the highest contribution to wind energy efficiency, with curved roofs showing particularly notable power generation improvements in low-wind environments. The building “density + layout angle + roof form” collaborative strategy has been validated for practical implementation. Current limitations include simulation errors in complex geometries, efficiency bottlenecks in vertical axis turbines, and inadequate lifecycle assessments. Future efforts should focus on multi-field coupled simulations, integrated turbine–architecture design, and enhanced low-carbon evaluation systems to facilitate the transformation of buildings into distributed energy production entities. Full article

(This article belongs to the Section G: Energy and Buildings)

► Show Figures

Figure 1

Journal Description

Energies

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI