Search Results (1,141)

Current research in commercial aviation is exploring numerous propulsion and aircraft technologies to mitigate its environmental impact. While purely hydrogen-powered aircraft face manifold challenges, combining hydrogen and conventional fuel may facilitate the introduction of hydrogen-based flight. This study dives into the conceptual design of a parallel-hybrid dual-fuel regional aircraft retrofit based on the D328eco. The assessed retrofit approach aims to extend airframe service life and reduce emissions by incorporating a novel propulsion system. By integrating high-temperature fuel cells (FCs) to assist conventional turboshaft engines, the powertrain reduces fuel consumption. Utilizing the Bauhaus Luftfahrt Aircraft Design Environment, various aircraft-level sensitivities and hybridization strategies were assessed. The fuel/payload ratio was identified as a key metric, and enabling FC support during diversion climb while minimizing that ratio shifted the corresponding hybridization degree from 20.3% to 37.2%. Retaining the reference turboshaft-engine for reduced retrofit development costs, a hybridization degree of 20.2% was attainable while the minimum allowable payload was carried aboard. Subsequent off-design mission analysis revealed a decrease in transport efficiency for reduced mission ranges, underlining the importance of market-tailored aircraft designs. The main studies were complemented by a higher-level emission and climate impact assessment to set the basis for more generalized retrofit statements. Full article

This study investigates the structural behavior of steel I-beams containing corrosion-induced section loss and web openings, along with the effectiveness of fiber-reinforced polymer (FRP) strengthening as a retrofit strategy. Although previous studies have investigated the effects of corrosion, web openings, and FRP strengthening in steel beams, limited attention has been given to comparing the structural response of slender and deep steel beams under these deterioration scenarios and assessing strengthening strategies according to their distinct failure mechanisms. The analysis considers two structural response regimes: slender beams governed predominantly by flexural behavior and deep beams where shear deformation plays a significant role. Three-dimensional (3D) nonlinear solid finite element (FE) models are developed to evaluate the influence of corrosion location, web opening position, and FRP-strengthening schemes on load-carrying capacity and failure behavior. The results indicate that corrosion-induced flange thinning significantly reduces flexural capacity in slender beams, while web degradation has a comparatively smaller effect. FRP strengthening of the tension flange is found to be the most effective strategy for restoring flexural performance in slender beam configurations. In contrast, deep beams exhibit higher sensitivity to shear-related damage, where web openings located in shear transfer regions lead to substantial reductions in load capacity. Strengthening of the web region using FRP significantly improves shear resistance and overall structural performance. Overall, the study highlights distinct differences in damage sensitivity and strengthening effectiveness between slender and deep beam responses under corrosion and web opening effects, providing practical guidance for condition assessment and retrofit design of deteriorated steel I-beams. Full article

To enhance the seismic performance of existing reinforced concrete (RC) buildings during retrofitting, the study introduces a new type of joint connected by a T-shaped steel plate. Compared with previous similar strengthening methods, this novel structure incorporating a post-installed beam not only effectively improves the mechanical properties of RC columns, but the connectors also further enhance the integrity of the post-installed beam. Low-cycle reversed loading tests on one cast-in-place specimen (RC) and three T-shaped steel plate connection specimens (TRC1–TRC3) were conducted to evaluate failure modes, hysteresis and skeleton curves, and energy dissipation. Results show that the novel joint failure concentrates at beam-end–column steel jacket weld seams and column-side steel plate cracking, while the core-zone concrete remains intact. Compared with RC, the novel joints TRC1–TRC3 exhibit bearing capacity variations of −1.03%~+15.80% and significantly enhanced energy dissipation. The thickness of the beam’s wrapped steel improves the carrying capacity and energy dissipation, whereas the T-shaped connector thickness has limited influence on bearing capacity. ABAQUS parametric analysis indicates that bolt quantity, concrete strength, and connector thickness have limited influence and serve as secondary design factors. These findings provide a theoretical basis for retrofitting existing buildings. Full article

Under the carbon neutrality context, underground coal gasification combined cycle (UGCC) power generation with carbon capture and storage (CCS) technology can effectively mitigate climate change and reduce pollutant emissions. However, due to the complexity of the UCG process and significant fluctuations in syngas composition, the overall power generation efficiency of the plant may be affected to some extent. Existing studies have predominantly focused on single-link energy efficiency analysis, with a lack of full life-cycle resource–environment synergistic evaluation based on the extended exergy analysis framework, and comparative sustainability research between UGCC and integrated gasification combined cycle (IGCC) systems remains inadequate. Accordingly, this study establishes an exergy Life-Cycle Assessment model for UGCC power plants based on Aspen Plus, systematically evaluates the resource utilization rate and environmental sustainability index, identifies key influencing factors, and conducts a comparative analysis with IGCC power plants. The results indicate that the comprehensive sustainability performance of UGCC power plants is significantly enhanced after CCS retrofitting, with exergy efficiency reaching 37.56% at an oxygen-to-coal ratio of 0.6 and a water-to-coal ratio of 0.1; compared with IGCC, UGCC demonstrates a superior resource utilization rate but relatively weaker environmental sustainability; and the underground gasification unit is the critical link affecting exergy efficiency. This study offers a new perspective for sustainability assessment of energy systems and provides theoretical support and technical reference for the construction of a low-carbon reliable supply system in the power industry, thereby facilitating the implementation and refinement of a novel sustainable energy system. Full article

Purpose: This study conducts a systematic literature review on the intersection of real estate exposure and geotechnical hazards, focusing specifically on seismic and subsurface risks. The objective is to synthesize key thematic trends, methodologies, and governance frameworks that inform risk-informed planning in seismically vulnerable urban areas. Design/methodology/approach: A Boolean search query was implemented on Lens.org, identifying 55 peer-reviewed articles published between January 2020 and May 2025. Inclusion criteria required explicit focus on property exposure to seismic or ground instability risks. Thematic analysis was conducted based on title and abstract data, supported by a Python (version 3.11)-generated word cloud to inductively identify five core clusters: (1) seismic assessment and earthquake risk, (2) building vulnerability and structural performance, (3) subsurface hazards and ground instability, (4) urban areas, heritage, and social vulnerability, and (5) risk mitigation, planning, and resilience frameworks. Findings: The review reveals a shift from hazard-centric, engineering-based models toward integrated, multi-scalar frameworks that embed risk within socio-economic, spatial, and institutional contexts. While consensus exists on the importance of probabilistic modeling, retrofitting, and GIS-based tools, divergences persist around behavioral valuation, policy uptake, and equity in implementation. Heritage cities and informal settlements emerge as under-addressed but critically vulnerable domains. Originality/value: This study systematically maps interdisciplinary research on real estate exposure to seismic and subsurface risks post-2020. By bridging engineering, planning, behavioral economics, and disaster governance, the review provides a unique synthesis relevant for academics, urban planners, and policymakers seeking to design equitable and resilient urban futures. The five-cluster thematic taxonomy introduced in this review represents an original synthesis that bridges engineering vulnerability assessment, behavioral economics, heritage preservation, and resilience governance. Unlike previous reviews that have typically focused on single disciplinary perspectives, this taxonomy integrates multi-scalar approaches spanning asset-level diagnostics to national exposure modeling, providing a comprehensive framework for understanding real estate exposure to seismic and subsurface risks. Full article

Viscoelastic dampers, leveraging the synergistic mechanism of viscous dissipation and elastic recovery, simultaneously reduce seismic-induced structural displacement and acceleration responses while offering the advantages of simple construction and ease of installation, which hold broad prospects in both the seismic design of new buildings and the retrofitting of existing structures. This work aims to propose a rapid optimization design method for viscoelastic dampers considering torsional effect for three-dimensional solid structures. First, a full-scale prefabricated assembled viscoelastic damper was developed, and mechanical property tests were conducted under a series of loading conditions. Based on the test results, a genetic algorithm is employed to optimize the design scheme of viscoelastic dampers through co-simulation using MATLAB R2022a and OpenSees. The optimization objectives consider both the inter-story drift ratio and acceleration response of the structure, with particular emphasis on the influence of torsional effects. Given that the proposed optimization scheme accounts for structural dynamic characteristics, building functionality, and the universality of seismic excitations, it serves as a design reference for the optimization analysis of other damped structures. Full article

Implementing Historic Building Information Modelling (HBIM) for heritage structures is challenged by incomplete knowledge of hidden or inaccessible elements, as well as limited information on construction history, original design, and structural details, making geometric definition inherently uncertain. Simultaneously, applications such as structural analysis often require the same missing information. This study proposes an adaptive parametric Scan-to-BIM-to-FEM workflow that explicitly incorporates geometric uncertainty by generating multiple plausible and complete reconstructions from survey data and typological inference, enabling their use in parametric structural analysis. Starting from TLS survey, adaptive families were used to link measured and inferred dimensions through geometric constraints. The methodology is applied to the 19th-century masonry arch bridge of Montoggio (Genoa, Italy), currently characterized by a hybrid structural system resulting from subsequent retrofitting. Eight geometrical configurations were tested by varying uncertain parameters, including vault thickness and backing height, and were analyzed through modal and static finite element simulations. The results show a limited but non-negligible sensitivity of the structural response to these parameters, highlighting the influence of geometric uncertainties on analysis outcomes. In this light, the proposed framework provides a bridge between survey, modelling, and structural analysis, enabling HBIM to support interpretative and predictive structural assessment. Full article

Simulation-dependent energy analysis has long dominated building retrofit research, yet this paradigm presents substantial barriers for non-expert building owners who lack technical software proficiency and detailed building documentation-a challenge compounded by the “curse of dimensionality” when multivariate analysis requires thousands of samples beyond available empirical records. Leveraging retrofit data accumulated through Korea’s Green Remodeling programs since 2017, this study proposes a Copula-Genetic Algorithm (Copula-GA) integrated framework that enables rational retrofit decision-making with minimal user inputs (construction year, floor area, structural type). From 178 documented retrofit cases, Gaussian copula-based multivariate sampling generated 10,000 synthetic records while preserving inter-variable dependency structures. Building physics constraints addressing vintage-thermal performance and capacity-efficiency relationships filtered implausible combinations, yielding 9898 valid cases with correlation matrix fidelity confirmed by a Frobenius norm deviation of 0.043. Evolutionary clustering employing a composite fitness function of Silhouette coefficient (0.68) and Davies-Bouldin Index (0.52) identified K = 16 as the optimal partition, categorizing outcomes into four reference model archetypes: Lightweight Structure (Type A, 27.0% reduction, 15.7-year payback), Masonry Structure (Type B, 29.0%, 14.8 years), RC Structure (Type C, 30.7%, 13.4 years), and Mixed Structure (Type D, 30.9%, 13.1 years). The proposed Copula-GA framework bridges the gap between advanced energy optimization methodologies and practical accessibility for non-expert building owners. By transforming limited empirical samples into reliable reference models, this research supports building-sector decarbonization. Using three minimal inputs, a building can be matched to one of the 16 standard models to obtain its expected saving rate, payback period, and recommended measures without detailed simulation. Full article

Residential buildings are central to decarbonisation because existing dwellings combine long service lives, high heating demand and heterogeneous constraints for retrofitting. This study investigates some retrofit strategies for a terraced house in Oxford, UK, to achieve the winter indoor air temperature set-point while reducing energy use, costs and CO₂ emissions. A calibrated dynamic simulation model was developed from on-site inspections, monitored temperatures, occupant schedules and energy-bill data. The analysis compares baseline configuration with scenarios including radiator power upgrading, envelope insulation, increased internal thermal mass and replacement of the condensing boiler with a high-temperature ground-source heat pump (GSHP). The results show that radiator upgrading enables the most critical rooms to reach the 20 °C set-point, while envelope insulation reduces heating energy and costs. Increased thermal mass improves night-time temperature stability, although its effect on annual energy demand is limited. The GSHP provides the largest primary energy reduction, lowering operational primary energy by 66.3% compared to the reference case and by 70.4% when combined with envelope and thermal-mass measures. Operational CO₂ emissions are reduced by 35.0–84.3%. The study highlights the need to evaluate the capacity of heat emitters, building envelope performance, thermal inertia and heat generator efficiency within a dynamic framework. Full article

Three-dimensional concrete printing (3DCP) enables the fabrication of wall sections with internal cavities that are impractical to form with conventional methods. Although individual studies demonstrate that cavity geometry influences thermal resistance, the magnitude of this effect has not been quantified on a common basis across the literature. This paper introduces the Thermal Effectiveness Index (TEI), defined as the ratio of the theoretical U-value of a solid concrete wall (calculated using the material’s actual thermal conductivity) to the reported U-value, in order to isolate the purely geometric contribution to thermal performance. A structured extraction from 24 Scopus-indexed articles yielded an analysis dataset of 255 variants from 23 articles (after the exclusion of one study whose composite mix made the geometric effect inseparable from material substitution), spanning 17 typology categories. Results show that standard rectangular air cavities perform worse than solid printed counterparts of the same material (median TEI $=0.56$ versus $1.00$ for solid walls) due to internal convection and thermal bridging, whereas sinusoidal infills with post-printed insulation reach a median TEI of 8.9 (18 variants from a single study, so the magnitude requires independent replication). These patterns are descriptive; an article-level sensitivity check indicates that the number of independent studies per wall-type group is not yet sufficient for confirmatory statistical inference. A compliance analysis against five building energy codes showed that only 22% of variants meet the $0.30$ $\mathrm{W}$/($\mathrm{m}$² $\mathrm{K}$) threshold, in line with the component-based U-value criteria specified in the Passive House Institute’s EnerPHit Standard for building retrofits and warm-climate classifications, as opposed to the more stringent $\le 0.15 \mathrm{W}/({\mathrm{m}}^2 \mathrm{K})$ requirement applicable to new construction in temperate climates. Full article

Public building retrofit is an important pathway for reducing operational carbon emissions, but evidence-based technology prioritisation remains limited under real-world multi-technology retrofit conditions. This study develops an interpretable data-driven framework to identify priority technologies and technology co-adoption patterns for public buildings in China’s Hot Summer and Cold Winter (HSCW) region. Based on 218 completed retrofit projects, the carbon reduction rate (CRR) was used as the performance indicator, and 15 retrofit technologies were analysed using FDR-adjusted Mann–Whitney U tests, repeated-validation XGBoost–SHAP analysis, and Apriori association-rule mining. The projects showed substantial variation in CRR, with a mean of 24.98% and a median of 21.70%. Across five repeated 5-fold cross-validations, the predictive XGBoost model achieved a mean R² of 0.417 and a mean RMSE of 0.127. Roof insulation, external wall insulation, and ventilation system retrofit showed the strongest combined evidence and were classified as core technologies. Apriori analysis further revealed three empirical co-adoption patterns: integrated passive-envelope retrofit, solar-control and renewable-energy integration, and operational-management improvement. The findings suggest that retrofit planning in the HSCW region should prioritise envelope insulation and ventilation performance, while selecting shading, system, renewable-energy, and operational-control measures according to project-specific conditions. Full article

The Net Zero debate is getting more contested as 25% of the UK emissions are directly attributable to the built environment, and 80% of it is expected to come from the existing building stock. Hence, decarbonising the existing building stock is significant, as the domestic housing sector dominates. There is a strong connection between the UK government policies and the progression of housing retrofit. However, limited studies have reviewed this interdependency. The Stern Review validated the importance of early action on climate change two decades ago. Ever since the UK adopted a strong climate change agenda when developing policies. This study aimed to analyse the housing retrofit policy actions over the last two decades and their influence on improving the performance of the housing stock. The study is limited to analysing policy actions relevant to England, which maintains the largest residential housing stock in the UK, with 26 million homes compared with Scotland’s 2.5 million, Wales’s 1.5 million and Northern Ireland’s 0.8 million, while keeping the narrative in the UK context. The detailed policy review, along with political party manifesto analysis, was undertaken as the main data collection strategy. The data was analysed chronologically to explain the patterns and underline narratives. Findings reveal that the existing retrofit policies are not always in favour of the broader sustainability requirements of the country. Governments have changed their direction quite often and focused on short-term priorities for long-term gains. There is a critical need for robust, consistent and transparent policies (interconnected with other policies) as a long-term strategy for achieving sustainable goals. Full article

Historic buildings represent a substantial share of the European building stock. However, their energy retrofit is heavily restricted by conservation principles that often exclude conventional insulation systems. In this context, phase change materials (PCMs) incorporated into lime-based mortars have emerged as a potentially compatible solution, combining latent heat storage capacity with the compatibility traditionally associated with aerial lime, the binder of reference in conservation practice. In some cases, natural hydraulic lime and hydrated lime are also used in heritage conservation applications. The aim of this study, therefore, is to provide a systematic review of peer-reviewed articles published between 2010 and 2026 that illustrate the use of PCM-containing lime mortars applied in historic buildings. The analysis examines PCM types, incorporation methods, thermal and mechanical behavior, durability, and compatibility with conservation requirements. The reviewed studies demonstrate that the incorporation of PCM generally reduces internal thermal fluctuations in buildings along with capillary water absorption. Durability investigations indicate improved resistance to freeze–thaw cycles and salt crystallization of mortars containing such PCMs. However, durability was investigated in less than 20% of the studies reviewed. Lime mortars show a consistent reduction in compressive strength as the PCM content increases; on the other hand, hydrated lime mortars can also offer increases in strength. Although the reviewed studies focused on applications in historic buildings, the reversibility of the intervention and its compatibility with historic substrates was not assessed according to the standards required for the conservation of cultural heritage. This gap represents the main limitation of the research conducted. Full article

Green remodeling projects for public buildings in South Korea aim to improve the energy performance of aging facilities, with a policy target of achieving at least 30% energy savings. Because the 30% saving rate functions as a key policy benchmark, it is necessary to identify why some projects achieve higher savings while others remain below the target. This requires a comparative analysis of energy-saving levels in relation to baseline energy-use composition and retrofit measure applications. This study analyzes the 1954 preliminary investigation and ECO2-OD-based assessment cases of public building green remodeling projects to examine energy-saving levels, baseline energy-use composition, end-use contributions, and retrofit measure applications. Pre- and post-retrofit primary energy demand for heating, cooling, domestic hot water, and lighting were used to calculate energy-saving rates. Based on the 30% policy target, the cases were classified into Low-saving, Target-achieving, High-saving, and Very-high-saving levels. The average energy-saving rate was 36.02%, but 39.61% of cases remained below the 30% target. Higher-saving groups showed greater baseline heating energy shares, increasing from 53.38% in the Low-saving group to 66.18% in the Very-high-saving group, suggesting an association between pre-retrofit energy-use structure and predicted retrofit potential under the ECO2-OD assessment framework. Heating was also the dominant contributor to total savings, with its contribution rising from 17.07 to 44.94 percentage points. Higher-saving cases tended to involve more comprehensive retrofit packages combining envelope, system, and lighting improvements. These findings suggest that energy-saving targets and retrofit strategies should consider baseline end-use energy composition and establish differentiated saving targets according to building characteristics, rather than relying only on uniform policy targets and average project performance. Full article

Urban Building Energy Modelling (UBEM) is increasingly recognised as a key tool for bridging building-scale analysis and city-level planning, supporting the decarbonisation of urban areas. It enables the assessment of building performance and the exploration of retrofit strategies, policy scenarios, and renewable integration. Over the past decade, UBEM has continuously evolved, encompassing physics-based, data-driven, and hybrid approaches, often supported by archetype generation and GIS workflows. Recent research also integrates microclimate, mobility, and green infrastructure. While this enriches analysis outcomes, it also leads to fragmentation, limiting tools’ comparability, transparency, and practical use by policymakers. This perspective paper provides a critical interpretation of the recent evolution in UBEM and proposes a goal-oriented classification of modelling approaches based on their final objectives rather than on calculation methodology. The paper also identifies three key gaps: the lack of scalable and consistent data frameworks, the absence of a shared terminology, and the need for criteria to assess whether models are “fit for purpose.” Addressing these issues through improved data infrastructures, conceptual clarity, and reliability assessment can support convergence without limiting innovation, fostering more robust and decision-relevant UBEM applications to support the energy transition. Full article