Search Results (519)

This study addresses the technical, environmental, economic, and systemic role of multi-apartment residential buildings as hydrogen consumption nodes within urban energy systems. A representative five-story building comprising 30 apartments and 2400–2800 m² of heated floor area, located in a cold European climate, was modelled with an annual heat demand of approximately 185,000 kWh. Four heating configurations were assessed: a conventional natural gas/biomethane boiler (baseline), a hydrogen boiler, a hydrogen-fuel-cell combined heat and power (CHP) system, and a hybrid heat-pump–hydrogen solution. Dynamic simulations indicate that all hydrogen-based systems can fully satisfy space heating and domestic hot water demand without modifications to the internal hydronic distribution network. The fuel cell CHP achieved an overall efficiency of 93%. It generated approximately 54,000 kWh/year of on-site electricity, while the hybrid configuration reached a seasonal efficiency of 108% and the highest primary energy reduction (46%). Operational CO₂ emissions decreased from 37,800 kg/year (gas baseline) to 1900 kg/year (green hydrogen boiler), 1200 kg/year (fuel cell CHP), and 900 kg/year (hybrid system), corresponding to reductions of up to 98%. Peak-load analysis demonstrated improved operational stability in CHP and hybrid systems, characterised by reduced cycling frequency and enhanced thermal resilience through hydrogen storage integration. Capital expenditure (CAPEX) ranged from 41,000 EUR (gas baseline) to 101,000 EUR (fuel cell CHP), reflecting additional storage, safety, and control requirements. Over a 20-year lifecycle (5% discount rate), the hybrid system achieved the lowest levelized cost of heat (0.076 EUR/kWh), followed by fuel cell CHP (0.081 EUR/kWh), compared to 0.087 EUR/kWh for gas. Payback periods ranged between 9 and 13 years, depending on configuration and hydrogen pricing assumptions. Sensitivity analysis identified a break-even hydrogen price of approximately 0.085 EUR/kWh, while carbon pricing above 100 EUR/t CO₂ significantly improves economic competitiveness. District-scale aggregation modelling suggests that hydrogen-equipped multi-apartment buildings can reduce grid electricity imports by 30–40% through on-site generation and seasonal storage. The findings confirm that multi-apartment buildings offer structural and economic advantages for early hydrogen deployment compared to dispersed housing typologies. By combining high demand density, centralised infrastructure, and compatibility with sector-coupling strategies, such buildings can function as distributed energy hubs within decarbonized urban systems. Full article

This study evaluates the spatial and seasonal feasibility of residential PV integration across 52 Spanish municipalities representing the country’s main urban areas. The assessment is based on the normalized photovoltaic sizing indicator (A_PV,N), defined as the PV area required to offset electricity demand per square metre of conditioned floor area. Simulations were performed under current climate conditions and future projections for 2050 and 2100 using the RCP4.5 scenario. Results reveal strong climatic and seasonal contrasts. Under current conditions, annual PV generation offsets approximately 17–18% of residential electricity demand. Southern and Mediterranean municipalities show the highest feasibility, with annual A_PV,N values of approximately 2–2.5, whereas northern and inland regions present severe winter limitations, with A_PV,N values frequently exceeding 15–20. Summer is the most favourable season, with PV systems covering more than 50% of seasonal demand in several southern municipalities. Future climate projections indicate a progressive improvement in PV feasibility. Under RCP4.5, annual A_PV,N decreases by approximately 5–10% by 2100, while the production-to-consumption (P/C) ratio improves by about 15–20% relative to present conditions, mainly due to reduced heating demand. The results demonstrate that future climate conditions may improve the viability of residential PV systems in Spain, particularly in southern and coastal urban areas, while northern regions will remain constrained during winter. The study provides quantitative benchmarks for climate-sensitive PV planning and long-term urban energy strategies. Full article

Fire protection remains one of the key challenges in the field of architectural heritage conservation, particularly for heritage buildings dominated by timber structures, which face greater difficulties in fire prevention and risk assessment. To systematically evaluate the fire safety performance of high-rise timber heritage buildings, this study takes the Shengjin Pagoda, a typical brick–timber pavilion-style ancient tower in Jiangxi Province, China, as the research object. A three-dimensional performance-based fire assessment framework was developed using Fire Dynamics Simulator (FDS) and PyroSim. Based on field survey data and historical documentation, the geometric characteristics, material properties, and vertical circulation system of the pagoda were reconstructed. Three representative fire scenarios, including bottom-floor ignition, simultaneous multi-level ignition, and wind-driven top-floor ignition, were established to investigate smoke propagation, thermal insulation degradation, and the thermal response of critical timber components under different fire conditions. The results show that brick walls provide effective thermal insulation during the early stages of fire, with efficiency exceeding 90%, but this decreases to approximately 55% in upper regions due to chimney-effect-driven smoke accumulation. Under wind-driven top-floor ignition, exposed dougong components can reach temperatures of 782 °C, resulting in a progressive “top-down and outside-in” failure mechanism. The study reveals the dominant smoke-driven heat transfer pathways and the failure sequence of critical load-bearing elements. Based on these findings, a performance-based fire protection strategy incorporating vertical virtual smoke control zoning and fire-resistance enhancement of key structural components is proposed to support the sustainable conservation of historic high-rise timber structures. Full article

The escalating energy consumption in China’s rural residences necessitates the adoption of targeted energy-efficient design strategies. However, existing studies have mainly focused on urban buildings or cold-climate rural residences, and insufficient attention has been given to form-based energy optimization for rural housing in hot summer and cold winter regions. Hangzhou was selected because it is a representative city in this climate zone, where rural residences face both summer cooling and winter heating demands. This study systematically investigates passive design pathways for rural residential buildings by optimizing architectural forms. We conducted in-depth field surveys and data analysis on 76 diverse samples, including both self-built and unified construction types, to establish three representative typical residential models (rectangular, L-shaped, U-shaped) for the Hangzhou region. DesignBuilder was employed to simulate the impacts of eight morphological elements—Shape Coefficient, building area, aspect ratio, orientation, number of floors, floor height, floor height ratio, and roof slope—on building energy consumption. The Gradient Boosting Decision Tree (GBDT) method was then used to quantify the nonlinear effects and relative importance of these elements. The results indicate clear nonlinear relationships between elements and the energy-saving rate. Floor height is identified as the most critical factor affecting energy consumption, followed by roof slope, with building area and other elements also showing significant influence. Based on the quantitative analysis, this study proposes energy-efficient design optimization strategies for rural housing in Hangzhou, offering a validated methodological framework and practical design references for the sustainable development of rural residences in hot summer and cold winter regions. Full article

Cities in climatic transition zones face coupled radiative and evaporative stresses, and their carbon emission mechanisms differ significantly from those in humid regions. Taking Xi’an, a typical megacity in the transition zone, as a case study, this research utilises a 500 m × 500 m grid to integrate multi-source data for carbon emission accounting. By applying spatial autocorrelation and the Multi-scale Geographically Weighted Regression (MGWR) model, this study examines the spatial heterogeneity of carbon emissions and the mechanisms through which urban planning influences them. The results indicate that carbon emissions in Xi’an exhibit a “core–periphery” agglomeration pattern, with commercial land use exhibiting the highest emission intensity. Carbon emissions and land surface temperature are spatially coupled, consistent with a hypothesised positive feedback loop of the “dry heat island” effect. Morphological factors exhibit spatial non-stationarity: floor area ratio is positively associated with emissions in the old city centre, whereas mutual shading among super-high-rise buildings in the High-Tech Zone coincides with a weaker effect. Building density shows a positive association only where ventilation is limited. Land use mix and blue–green spaces show non-linear negative associations with emissions, with higher marginal benefits in arid–hot environments. This study proposes carbon reduction strategies for the renewal of old urban areas, business cores, and new ecological districts, providing empirical evidence and decision-making references for low-carbon spatial planning in cities within the climatic transition zone. Full article

This study investigates the optimization of the building envelope parameters of a duplex residential building in Elazig, Türkiye, in line with nearly-zero energy building (nZEB) requirements. The annual energy performance of the case study building was calculated using national BEP-TR version 2.0 software authorized by the Turkish Ministry of Environment, Urbanization, and Climate Change. Wall, roof, floor, and window overall heat transfer coefficients (U-values) were selected as design parameters, and experiments were conducted using the Taguchi method, a well-known experimental design approach, based on an L9 orthogonal array. The results obtained from the Taguchi design were then evaluated using analysis of variance (ANOVA) and grey relational analysis (GRA) to assess energy savings, total initial investment cost, and payback period simultaneously. In accordance with the Türkiye nZEB regulation, photovoltaic (PV) systems were also incorporated to supply at least 10% of the annual energy demand, and their investment cost was included in the economic analysis. The results showed that the wall U-value was the most influential parameter affecting annual energy savings, with a contribution ratio of 49.98%, whereas the window U-value had the dominant effect on total initial investment cost and payback period, with contribution ratios of 93.30% and 95.44%, respectively. The optimum multi-performance combination obtained by GRA was A3B2C1D1, corresponding to wall, roof, floor, and window U-values of 0.25, 0.19, 0.28, and 1.7 W/m²K. These findings offer a practical framework for balancing energy efficiency, investment costs, and regulatory compliance in the design of residential nZEBs in cold-climate conditions. Full article

Both developed and developing countries are striving to reduce building energy consumption. Heating still accounts for an important share of the total energy used in buildings. Many studies compare different heating modes, but few take into account that, first of all, in heated rooms, similar operative temperatures should be provided. In this study, operative temperatures in different locations of a heated room have been analysed, assuming two different heating systems. In addition, the operative temperature distribution can be further disturbed by the room geometry (one or more external walls, or family house) and the room’s position in the building (ground floor, intermediate floor, or top floor). The operative temperature distribution was analysed at nine locations across 525 different room models for radiator and floor heating. The conducted research proved that, at the p = 0.05 significance level, the differences in operative temperatures across locations in a radiator-heated room are significant. Differences in operative temperatures across locations in a floor-heated room are significant and the number of external walls (one, two, or three) also have a significant effect on operative temperatures in a heated room. The differences in operative temperatures at the same location in a heated room with different dimensions can be significant. The differences between the mean operative temperatures in a room (radiator-heated or floor-heated) are not significant if the room has different positions in a multilevel building (ground floor, intermediate level, or top level). To compare two heating systems energetically, a complex analysis should be conducted, and efforts should be made to ensure similar operative temperatures at the most critical locations. Full article

Great Britain has a temperate climate, but like other countries, its weather patterns have already been profoundly affected by climate change, and the changes are very likely to continue for decades. It also has an older building stock than most other countries, which may mean it is more difficult to adapt the built environment to reduce vulnerability to climate hazards. However, Great Britain has excellent mapping and buildings data. The built environment is better described than most other countries, and the authors’ work on the National Buildings Database for Great Britain, which draws together the most reliable sources of data covering non-domestic buildings in England, Scotland and Wales, provides an unparalleled opportunity to evaluate how many people will be affected by climate hazards. There has been considerable research effort assessing how housing will be affected by climate change, but so far much less systematic assessment of impacts on non-domestic buildings. Here, the authors examine three aspects of climate hazard affecting people in non-domestic buildings in Great Britain: (1) Overheating—How many and what types of non-domestic buildings are vulnerable to overheating risks in a heat wave? What total floor area is affected, and how many people typically occupy these buildings? (2) Flooding—How many and what types of non-domestic buildings are threatened by flooding now and in 2080? How much floorspace is threatened, and how many people typically occupy these buildings? (3) Safe space—How much air-conditioned ‘safe space’ is available where people vulnerable to overheating risks could retreat to in an emergency overheating event (e.g., schools or hospitals)? How many people could be accommodated, and what fraction of the total GB working population does this represent? We propose five new metrics to assess two of the immediate hazards posed by climate change (overheating and flooding) and to begin to assess to what extent Great Britain could find temporary accommodation for people displaced by these hazards. Full article

Establishing a reliable heating energy benchmark for urban buildings is essential for effective energy management, yet benchmark accuracy is often constrained by multiple building characteristics and uncertainty in energy prediction. This study investigated the influence of scale heterogeneity on the heating energy use intensity (EUI) of office buildings. A Bayesian surrogate model was developed, trained, and validated, yielding acceptable accuracy, with a CVRMSE of 12.37% and an NMBE of −1.02%, both within the limits recommended by ASHRAE Guideline 14-2023. The validated model was then used to simulate the heating EUI of office buildings with floor areas from 100 to 100,000 ${\mathrm{m}}^2$ under climatic conditions ranging from 3250 to 9698 HDD65. The results showed a clear inverse relationship between building scale and heating EUI. Smaller buildings were more sensitive to scale variation, with pronounced declines around 1000 and 3000 ${\mathrm{m}}^2$, while the decline rate weakened beyond 5000 ${\mathrm{m}}^2$. Climatic severity remained the dominant factor controlling the absolute level of heating demand, but the climatic differences in heating EUI gradually narrowed as building scale increased. Moreover, the scale effect persisted longer under colder climatic conditions. These findings provide a reference for establishing scale-sensitive heating energy benchmarks in urban public buildings. Full article

Analysis of Estates Return Information Collection (ERIC) 2018/19–2024/25 data for 1104 acute NHS hospital sites in England found persistently high energy use intensity (EUI), averaging 211 kWh/m² in 2024/25, with total acute-sector energy use of 9.99 billion kWh, with approximately 75% derived from gas. Longitudinal trends indicated relatively stable EUI despite portfolio growth. Cross-sectional exploratory analyses for 2024/25 showed that clinical floor area share (mean 59%) exhibited the strongest observed association with EUI (r = 0.52, R² = 0.27), followed by gross internal area (r = 0.39, R² = 0.15) and backlog intensity (r = 0.23). Associations between building age cohorts and EUI were generally weak or negligible, except for a weak positive association for 1985–94 buildings (r = 0.064) and a moderate negative association for 2005–14 buildings (r = −0.126). Among the decarbonization and operational indicators examined, renewable electricity fraction showed the strongest bivariate association with EUI (R² = 0.224), followed by water intensity (R² = 0.101), gas share (R² = 0.085), LED coverage (R² = 0.027), climate incidents (R² = 0.020), and waste intensity (R² = 0.004). Sites with heat decarbonization plans, high LED coverage, or heat pump installations tended to exhibit higher EUI values alongside differing renewable electricity uptake patterns, potentially reflecting the prioritization of interventions at more energy-intensive facilities. Overall, the findings suggest that hospital energy intensity is associated with functional mix, estate characteristics, and decarbonization-related indicators, although these relationships should be interpreted as exploratory associations rather than independent causal effects. The study provides a national-scale exploratory benchmarking assessment intended to inform future multivariable and longitudinal research on NHS estate decarbonization strategies. Full article

Dry rooms used in battery and semiconductor research facilities require ultra-low dew-point environments, which demand significant thermal energy for desiccant rotor regeneration. In steam-regenerated systems, condensate discharged through steam traps partially evaporates due to pressure reduction, generating flash steam that is typically released into the atmosphere, resulting in substantial energy losses. This study investigates the generation and recovery potential of flash steam in dry room HVAC systems. Field measurements were conducted for 18 steam-regenerated desiccant air handling units installed in a medium-scale research facility (total floor area: 43,000 m²) in southern Gyeonggi Province, Korea. Boiler operation data—including feedwater flow rate, pressure, and operating time—were analyzed over a six-month period from March to August 2025. The results showed that the average flash steam generation rate was approximately 1.16 ton/h, corresponding to 8.56% of the average feedwater flow rate. Two recovery methods were evaluated: a steam jet thermocompressor (SJT) and an exhaust vapor condenser (EVC). The analysis revealed that the EVC system provides a more practical solution for medium-scale dry rooms because it does not require high-pressure primary steam. By recovering flash steam using three EVC units, an average heat recovery of 724 kW was achieved. The recovered heat can produce 86 °C hot water, which can be utilized as a driving heat source for an absorption chiller, generating approximately 507 kW of cooling capacity. This configuration partially offsets the cooling load of existing centrifugal chillers, thereby reducing electrical energy consumption. In addition, the proposed system eliminates atmospheric discharge of flash steam, mitigating the visible white plume phenomenon commonly observed in industrial facilities. The results demonstrate the technical feasibility of integrating flash steam recovery with absorption cooling to enhance energy efficiency in medium-scale dry room HVAC systems. Full article

Fixed external louvers are widely used to improve the environmental performance of glass curtain wall office buildings, yet existing studies more often report preferred solutions than transferable decision ranges for early-stage design. This study develops interval-based design rules for a standard-floor prototype of a point-supported glass curtain wall office building in Tianjin, a representative cold-climate city in China. A seven-variable design space integrating spatial-scale and shading variables was evaluated for 3000 Latin hypercube samples in a Rhino–Grasshopper–Honeybee workflow linked to Radiance and EnergyPlus, using Tianjin’s typical meteorological year data and GB 55015—2021-based office schedules, including an occupant density of 10 m²/person and occupied heating/cooling setpoints of 20/26 °C. Raw-sample statistics, Bootstrap-based stability testing, and surrogate-model-assisted continuous-response analysis were used to identify dominant variables, single-objective preferred intervals, and a neutral equal-weight baseline compromise zone. Under a neutral equal-weight baseline adopted for early-stage comparison, the compromise interval is concentrated around 20–25°, with 15–30° as a practical starting range, while alternative weighting scenarios show directional shifts toward the prioritized objective. Full article

With global warming and accelerated urbanization, building air-conditioning (AC) releases more heat into the environment, exacerbating the urban heat island (UHI) effects and increasing building cooling energy consumption. Existing research has limited quantification of the impact of air-conditioning anthropogenic heat (ACAH) on the cooling energy consumption of different types. This study aims to explore the distribution characteristics of ACAH and its impact on residential building energy consumption. Firstly, typical residential buildings in the Pearl River Delta region were selected as a case study. Field experiments were conducted to measure temperature and humidity at 0.5 m, 1 m, 2 m, and 3 m from the outdoor unit, alongside ambient temperature and wind speed. Three grid densities were applied to verify the CFD model, with a prediction error of less than 0.3 °C at 0.5 m under a medium grid. The simulated temperature at 1 m from the outdoor unit under calm wind conditions was compared with field measurements to reveal the horizontal and vertical distribution characteristics of ACAH. Secondly, the effects of different building shapes, ambient temperatures, and wind speeds on the spatial distribution of ACAH were investigated. Finally, EnergyPlus (V23.1.0) was employed as the building energy simulation software, with its microclimate coupling interface implemented via Python scripts to quantify cooling energy consumption variations across different building floors under ACAH influence. Results indicated that ACAH exhibits significant horizontal non-uniformity, exerting the greatest impact within a 0.5 m radius (affected air temperature 4.3 °C higher than ambient). Vertically, localized heat accumulation occurs in the building’s central area, with air temperature 3.5 °C higher than at the bottom. Furthermore, compared to fixed meteorological conditions, the cooling energy consumption difference across floors considering ACAH reaches approximately 7.8%. This study provides accurate meteorological boundary conditions for building energy assessment and supports microclimate management in residential areas. Full article

A three-dimensional steady-state thermomechanical contact formulation based on the Boundary Element Method is presented for the analysis of systems involving internal linear heat sources. The formulation consistently couples thermal conduction and thermoelastic contact effects within a boundary integral framework and is suitable for layered configurations governed by interface interactions. The approach is first validated through benchmark problems and subsequently applied to the analysis of a radiant floor system composed of a self-levelling compound and a surface floor covering supported by an elastic foundation. Linear heat sources representative of heating pipes are embedded within the compound layer, and the influence of their vertical position on the thermal and mechanical response of the system is investigated. The results show that the mean surface temperature exhibits an approximately linear dependence on the depth of the heat sources, indicating a high sensitivity of the thermal response to installation parameters. An extended scenario accounting for constrained displacements at the upper edge is also analysed in order to represent more realistic boundary conditions. Under these conditions, partial interface separation induced by thermal expansion leads to a reduction in the heat transferred towards the surface and to lower surface temperature levels. The proposed formulation provides a physically consistent and efficient framework for the analysis of thermomechanical contact problems with localized heat sources, offering an alternative tool for the investigation of layered floor systems and related engineering applications. Full article

Controlling operation-stage carbon emissions (CE) from transport buildings is crucial for China’s dual-carbon goals and the ecological security of the Qinghai–Tibet Plateau (QTP), and the sustainable development of plateau transport infrastructure. For plateau railway passenger stations (RPS), limited monitoring and distinctive high-altitude, cold-climate operations make daily CE prediction difficult with conventional measurement- or simulation-based methods. This study develops a machine-learning approach based on a Monte Carlo synthetic database and derives engineering-standard formulas for direct use. Building scale, meteorology and passenger flow volume (PFV) were compiled for 12 representative RPS, and a large synthetic database of daily carbon emission was generated under multiple distribution constraints. With daily mean temperature, heating degree days, altitude, station floor area and PFV as inputs, four models were trained and assessed using mean absolute error, root mean square error, mean absolute percentage error (MAPE) and R². The results show that random forest (RF) performed best, achieving ~6% MAPE and R² > 0.99 on the test set, and markedly lower errors than multivariable linear regression. Interpretation of RF via feature importance and partial dependence shows that floor area, altitude and PFV dominate emissions and exhibit nonlinear response patterns. To improve transparency and transferability, ridge regression was used to fit a linear surrogate to RF predictions, producing engineering-standard formulas for daily and annual operation-stage CE. The formulas retain most predictive accuracy while requiring only readily obtainable variables, enabling rapid estimation and scenario analysis for cold, high-altitude RPS. The proposed workflow provides a replicable pathway for operational CE assessment in data-scarce regions and supports low-carbon planning, design and operation of RPS on the QTP, thereby contributing to more sustainable infrastructure development in high-altitude regions. Full article