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Reducing energy use within the building sector is vital to create sustainable cities and mitigate global warming. Urban building energy modelling (UBEM) is useful to evaluate energy demand and renovation potential in districts. In this paper, an archetypes-based calibration approach for UBEM is introduced to evaluate the effect of various timescales for energy data and detail of building-related data on the energy performance of multi-residential buildings. A case district in northern Sweden was used to identify the impact of various refurbishment strategies at district-scale.

The applicability of the archetypes-based calibration approach was validated by comparing the district model performance with high-resolution energy data. Calibrating the archetypes-based model with monthly resolution data showed a similar outcome as using higher-resolution data. Further, a district model with less archetypes can reduce modelling time and complexity, while performing similarly as a model consisting of more archetypes with higher detail. The results suggest that simplifications to UBEM can be used without compromising the performance accuracy and might facilitate district modelling in situations with data limitations.

The findings in this study contribute to the knowledge on UBEM of existing districts and energy efficiency measures’ impact on district-level energy performance.

Accurate Cloud Behavior Prediction (CBP), also referred to as forecasting in this context, is essential for Solar Power Prediction (SPP), as well as for weather forecasting, climate analysis, and satellite imaging. However, the nonlinear and dynamic nature of clouds, combined with other limitations, presents significant challenges to advancing CBP. Recent developments, particularly the integration of Machine Learning (ML), Numerical Weather Prediction (NWP), and other innovative approaches, show strong potential for improving CBP and, in turn, enhancing SPP and related applications. This review presents a bibliometric analysis of 467 publications from 1970 to 2024, retrieved from the Scopus database using CBP-related keywords. It identifies trends, influential studies, major subject areas, leading authors, contributing countries, and key publishers. The study further categorizes the essential steps in CBP and provides a detailed review of the most relevant literature on cloud cover, cloud motion (including vector-based methods), and cloud image prediction. Additionally, it examines critical factors affecting model performance and introduces a framework for evaluating predictive methods based on input types, methodologies, prediction horizons, results, and evaluation metrics. Several key challenges are highlighted, including the nonlinearity of cloud behavior, limited data availability, image quality issues, and model accuracy. In response, actionable recommendations are offered, such as expanding data sources, applying hybrid imaging and modeling approaches, managing uncertainty, improving postprocessing techniques, and incorporating cloud content estimation. Given the relatively limited research in this field, this study serves as a valuable benchmark for researchers, engineers, and policymakers engaged in real-time SPP and other cloud-dependent domains.

Polyurethane (PU) as a popular polymer is widely recognized for its exceptional thermal insulation properties, making it a critical material for applications requiring effective heat transfer management. Integrating Phase Change Materials (PCMs) into PU (PU-PCMs) has emerged as a highly effective strategy for enhancing building envelope performance, ensuring greater indoor thermal stability, and mitigating temperature fluctuations. This study introduces an Enhanced Multi-Scale Modeling approach to investigate the thermal conductivity and energy efficiency of PU-PCMs, with a particular focus on their comparative performance in subarctic and tropical climates. By combining Molecular Dynamics (MD) simulations with Finite Element Methods (FEM), the model seamlessly bridges molecular-scale interactions with macroscopic thermal behavior. Using a Representative Volume Element (RVE)-FEM framework, microscopic properties are translated into engineering-scale parameters, enabling accurate and efficient predictions of material performance across diverse climatic conditions. The findings demonstrate the capability of PU-PCMs to significantly enhance energy efficiency and indoor thermal comfort. In a case study of a single-family house, PU-PCMs achieved a 7.376% reduction in energy consumption and increased comfort hours under Stockholm's subarctic climate. Moreover, the adaptability of PU-PCMs was validated in both tropical and subarctic environments, consistently stabilizing indoor temperatures, reducing HVAC energy demands, and improving occupant comfort. These results underscore the potential of PU-PCMs as a passive thermal management solution, advancing sustainable building practices. The proposed multi-scale model offers a computationally efficient and precise tool for optimizing material design in energy-sensitive applications, reinforcing the versatility and significance of PU-PCMs across a range of climatic conditions.

The advancement of artificial intelligence (AI) in material design and engineering has led to significant improvements in predictive modeling of material properties. However, the lack of interpretability in machine learning (ML)-based material informatics presents a major barrier to its practical adoption. This study proposes a novel quantitative computational framework that integrates ML models with explainable artificial intelligence (XAI) techniques to enhance both predictive accuracy and interpretability in material property prediction. The framework systematically incorporates a structured pipeline, including data processing, feature selection, model training, performance evaluation, explainability analysis, and real-world deployment. It is validated through a representative case study on the prediction of high-performance concrete (HPC) compressive strength, utilizing a comparative analysis of ML models such as Random Forest, XGBoost, Support Vector Regression (SVR), and Deep Neural Networks (DNNs). The results demonstrate that XGBoost achieves the highest predictive performance ((Formula presented.)), while SHAP (Shapley Additive Explanations) and LIME (Local Interpretable Model-Agnostic Explanations) provide detailed insights into feature importance and material interactions. Additionally, the deployment of the trained model as a cloud-based Flask-Gunicorn API enables real-time inference, ensuring its scalability and accessibility for industrial and research applications. The proposed framework addresses key limitations of existing ML approaches by integrating advanced explainability techniques, systematically handling nonlinear feature interactions, and providing a scalable deployment strategy. This study contributes to the development of interpretable and deployable AI-driven material informatics, bridging the gap between data-driven predictions and fundamental material science principles.

Graphene-based polymer nanocomposites show great potential for thermal management, but accurately predicting their thermal conductivity remains challenging due to multiscale structural complexity and parameter uncertainty. We propose an innovative approach integrating interpretable stochastic machine learning with multiscale analysis to predict the macroscopic thermal conductivity of graphene-based polymer nanocomposites. Our bottom-up framework addresses uncertainties in meso- and macro-scale input parameters. Using Representative Volume Elements (RVEs) and Finite Element Modeling (FEM), we compute effective thermal conductivity through homogenization. Predictive modeling is powered by the XGBoost regression tree-based algorithm. To elucidate the influence of input parameters on predictions, we employ SHapley Additive exPlanations (SHAP) and Local Interpretable Model-agnostic Explanations (LIME), providing insights into feature interactions and interpretability. Sensitivity analyses further quantify the impact of design parameters on material properties. This integrated method enhances prediction accuracy, reduces computational costs, and bridges data-driven and physical modeling, offering a scalable solution for designing advanced composite materials for thermal management applications.

Characterizing the energy performance of building components and locating anomalies is necessary for effectively refurbishing existing buildings. It is often challenging because defects in building envelopes deteriorate without being visible. Passive infrared thermography (PIRT) is a powerful tool used in building inspection. However, thermal image interpretation requires significant domain knowledge and is prone to artifacts arising from a complex interplay of factors. As a result, PIRT-based inspections require skilled professionals, and are labor-intensive and time-consuming. Artificial intelligence (AI) holds great promise to automate building inspection, but its application remains challenging because common approaches rely on extensive labeling and supervised modeling. It is recognized that there is a need for a more applicable and flexible approach to leverage AI to assist PIRT in realistic building inspections. In this study, we present a label-free method for detecting anomalies during thermographic inspection of building envelopes. It is based on the AI-driven prediction of thermal distributions from color images. Effectively the method performs as a one-class classifier of the thermal image regions with a high mismatch between the predicted and actual thermal distributions. The algorithm can learn to identify certain features as normal or anomalous by selecting the target sample used for training. The proposed method has unsupervised modeling capabilities, greater applicability and flexibility, and can be widely implemented to assist human professionals in routine building inspections or combined with mobile platforms to automate the inspection of large areas.

Ground fault relays (GFRs) in resonant-grounded medium voltage distribution networks shall not operate during phase-to-ground (Ph-G) fault inception, allowing the Petersen coil to suppress self-extinguishing faults, but the designated GFR must operate during permanent faults. In order to enhance the performance of GFRs, particularly during high-impedance faults, the scope of this paper is to propose a straightforward, machine-learning-based protection framework. The enhanced GFR is modeled as a classification task. Depending on the GFR's position and the Ph-G fault location in the network, fault samples are labeled as “no operation,” “primary,” “backup,” or “backup of backup,” forming two-class, three-class, and four-class GFR setups, respectively. This assures selective operation across three protection zones and improves the reliability of all GFRs. The proposed protection scheme employs backward optimal feature selection to identify the most relevant discrete features obtained from measured zero-sequence current and voltage waveforms. An ensemble of k-nearest neighbor classifiers is utilized for accurate classification, simulating the GFR operating conditions, with measurement errors and sensitivity incorporated in the preprocessing. A 20 kV case study network validates the proposed framework, achieving F1-scores exceeding 96 %. The maximum operation delay of the protection scheme for an enhanced GFR is 225 ms, accommodating the required time window (200 ms), prediction time (5 ms), and change detection time (20 ms), thus assuring safe operation. Compared to other machine-learning-based methods used for Ph-G fault protection in resonant-grounded radial networks, this framework is high-performing, fast, and easy to implement, utilizing a simpler structure than neural networks.

We've devised an interpretable stochastic integrated machine learning method for predicting thermal conductivity in Polymeric Graphene-Enhanced Composites (PGECs) across different scales. Our approach, integrating techniques like Regression Trees methods (Gradient Boosting machine), handles uncertain parameters via a bottom-up multi-scale framework using Representative Volume Elements in Finite Element Modeling (RVE-FEM). To understand factors affecting predictions, we use the SHapley Additive exPlanations (SHAP) algorithm. This method aligns well with training data, offering promise for efficiently designing new composite materials for thermal management.

The growth of computing power in data centers (DCs) leads to an increase in energy consumption and noise pollution of air cooling systems. Chip-level cooling with high-efficiency coolant is one of the promising methods to address the cooling challenge for high-power devices in DCs. Hybrid nanofluid (HNF) has the advantages of high thermal conductivity and good rheological properties. This study summarizes the numerical investigations of HNFs in mini/micro heat sinks, including the numerical methods, hydrothermal characteristics, and enhanced heat transfer technologies. The innovations of this paper include: (1) the characteristics, applicable conditions, and scenarios of each theoretical method and numerical method are clarified; (2) the molecular dynamics (MD) simulation can reveal the synergy effect, micro motion, and agglomeration morphology of different nanoparticles. Machine learning (ML) presents a feasible method for parameter prediction, which provides the opportunity for the intelligent regulation of the thermal performance of HNFs; (3) the HNFs flow boiling and the synergy of passive and active technologies may further improve the overall efficiency of liquid cooling systems in DCs. This review provides valuable insights and references for exploring the multi-phase flow and heat transport mechanisms of HNFs, and promoting the practical application of HNFs in chip-level liquid cooling in DCs.

Polyurethane (PU) is an excellent thermal insulator, and incorporating Phase Change Material (PCM) capsules into PU significantly enhances building envelope performance by improving indoor thermal stability and reducing temperature fluctuations. We propose a hierarchical multi-scale model using Physics-Informed Neural Networks (PINNs) to accurately predict and analyze the thermal conductivity of PU-PCM composites at both micro and macro scales. This approach effectively addresses complex inverse problems and multi-scale phenomena, offering insights that optimize material design. A case study further demonstrates the model's potential in improving thermal comfort and reducing energy consumption in buildings. The successful development of this PINNs-based model holds great promise for advancing PU-PCM applications in thermal energy storage and innovative building insulation design.