Search Results (2,849)

This paper presents an analysis of indoor air quality (IAQ) and occupant perception under different mechanical ventilation operational modes in a university amphitheater. Indoor environmental parameters, including air temperature, relative humidity, indoor air velocity, and CO₂ concentration, were measured in accordance with ISO 7726. Ventilation performance and outdoor air supply requirements were evaluated according to BAS EN 16798-1 and ASHRAE 62.1, while thermal comfort interpretation followed ISO 7730. In parallel, a questionnaire survey was conducted to assess occupants’ perceptions of indoor air quality and its influence on concentration under different ventilation operating conditions. The results showed that CO₂ concentrations occasionally exceeded 1000 ppm during extended occupancy periods but remained below 800 ppm for more than 60% of the measurement time. According to BAS EN 16798-1, the indoor environment was predominantly classified as Category I based on the indoor–outdoor CO₂ concentration difference. Survey responses indicated that most students perceived the indoor air as clean, while 67% reported that IAQ influenced their ability to concentrate. The findings highlight the importance of occupancy-related ventilation control strategies in large educational spaces and demonstrate the potential for balancing indoor air quality and energy efficiency through appropriate ventilation system operation. The presented methodology may support future development of data-driven approaches for optimizing mechanical ventilation performance in university buildings. Full article

Central heating systems often rely on uniform regulation, making it difficult to meet the differentiated comfort demands of users and frequently leading to overheating. This paper proposes an end-to-end, data-driven framework that systematically couples density-adaptive clustering with dynamic response modeling for precision heating control. First, an adaptive DBSCAN (Density-Based Spatial Clustering of Applications with Noise) algorithm is developed, which automatically determines its parameters via k-distance graph initialization, differential evolution optimization, and hierarchical clustering post-processing. Without requiring a pre-set cluster number, it consistently identifies four typical daily room temperature fluctuation patterns. Validated on 120-day data from a residential community in Luoyang, the first four clusters cover over 80% of users, and the clustering quality approaches that of manually optimized conventional methods. Second, multi-input ARX (Autoregressive with Exogenous Inputs) models are built for the representative user of each cluster to characterize dynamic responses to supply water temperature, flow rate, and outdoor temperature. Rolling prediction for the entire community achieves an RMSE of 0.24 °C and an R² of 0.93. Finally, a differentiated regulation strategy combining main-cluster supply temperature control and small-cluster flow compensation is designed. Simulation results demonstrate that this strategy drives the room temperatures of all clusters significantly toward the 20 °C comfort target, with a marked reduction in standard deviation. The primary contribution of this study lies in the construction of a reproducible, closed-loop pipeline—from raw room temperature data to demand-based regulation logic—offering a quantitative basis for central heating systems transitioning from passive balancing to data-driven, classified control. Full article

Head-mounted displays (HMDs) create a direct physical interface with the head and face that can constrain comfort during sustained and repeated virtual reality use. This focused narrative review examines three interacting domains of HMD physical comfort: thermal conditions at the headset–skin interface, mechanical loading from head-supported mass and contact forces, and anthropometric compatibility between headset geometry and user anatomy. Exploratory searching was followed during revision by structured searches of Google Scholar, Scopus, and Web of Science, tracker-based screening, source classification, evidence extraction, and evidence-limitation appraisal. The tracker-based review retained 41 sources, including 28 domain-focused and 13 context or framing sources. Two additional contextual references supplied during peer review were incorporated outside the completed tracker-based process, resulting in 43 sources cited in the final manuscript. Thermal comfort was influenced by microclimate conditions, exposure, activity, sealing, and internally generated heat. Mechanical comfort depended on mass, center-of-mass position, pressure, movement, posture, and task demands. Anthropometric evidence demonstrated substantial variation relevant to headset fit and alignment. The heterogeneous evidence does not support universal limits for headset mass, temperature, pressure, cervical angle, or interface geometry. Sustained HMD comfort therefore requires integrated evaluation across devices, users, tasks, and exposure durations. Full article

Providing a healthy environment in schools, particularly during a global pandemic, is crucial to saving occupants’ lives and reducing infection rates. This paper proposes a novel desk local exhaust ventilation (DLEV) system that uses a local exhaust diffuser integrated into a classroom desk. The performance of the system in providing a healthy and comfortable indoor thermal environment and reducing the risk of COVID-19 infection was assessed numerically. The assessment combined indoor thermal comfort indices and the bioaerosol dispersion behavior of airborne particles. The study was completed in a typical classroom layout, in which the results show that the DLEV system meets thermal comfort requirements by maintaining the gradients of vertical temperature within an acceptable range. The DLEV system increases the air motion in the breathing zone while keeping it within the recommended range of <0.25 m/s. The PMV and PPD indices are within recommended comfort levels for all but three occupants. Most notably, the DLEV system substantially reduces the concentration of bioaerosols, especially around the occupants’ head. This system works by capturing and removing the virus-rich aerosols exhaled by infected subjects before they disperse in the classroom. This lowers the risk of infection among healthy subjects. These findings confirm the effectiveness of the DLEV system in enhancing both thermal comfort and indoor air quality, making it suitable for environments where specific goals regarding occupants’ health and thermal management are required, such as in a classroom of healthy and infected subjects. Full article

Vanadium dioxide (VO₂), a typical thermochromic material, undergoes a metal–semiconductor transition (MST) near 68 °C, accompanied by lattice distortion and band structure reconstruction, making it an ideal material for smart window applications. However, VO₂ faces several bottlenecks that limit its engineering applications, including a relatively high phase transition temperature, poor color comfort, trade-offs between visible light transmittance and solar modulation efficiency, and inadequate long-term stability. This paper first discusses the structural evolution and mechanisms of the VO₂ phase transition. It then focuses on the three core performance aspects of VO₂-based smart windows: phase transition temperature regulation, color regulation, and optical performance regulation. Furthermore, it systematically reviews the latest research advancements in key technologies, including elemental doping, interfacial strain engineering, micro- and nanostructure engineering, multilayer film design, and inorganic–organic composite modification. Finally, the paper analyzes current challenges in terms of long-term stability, low-temperature flexible fabrication, skin comfort, and environmental friendliness, and discusses optimization pathways and future prospects for the practical application of VO₂-based smart windows. Full article

In the broader context of ecological transition, it is essential to identify solutions that ensure indoor environmental quality encompassing thermal, visual, acoustic, and indoor air quality conditions to safeguard occupant health and well-being. These solutions should also meet the demand for energy-efficient buildings. With specific regard to thermal environments, a distinction must be made between residential and non-residential settings, where comfort conditions can be achieved, and industrial environments, where thermal stress—and consequently health risks—may arise. To evaluate the quality of a thermal environment, key metrics are necessary. These include the Predicted Mean Vote (PMV) and the Predicted Percentage of Dissatisfied (PPD) for global thermal comfort, Predicted Heat Strain (PHS) and the Wet Bulb Globe Temperature (WBGT) for hot environments, and Required Insulation (IREQ) for cold environments, all governed by ISO-EN standards. The use of indices in residential and non-residential buildings outlines two critical challenges. The first relates to the fact that, in certain instances involving non-air-conditioned buildings, conditions can be borderline between comfort and thermal stress, which must be accurately identified. Secondly, the application of indices frequently neglects necessary variables, disregarding the fundamental limitations and operational boundaries inherent to both objective and personal input quantities. Moreover, the use of measurement devices inconsistent with the minimum requirements laid down by the standards in the field results in unwanted biases with unforeseeable consequences. This review explores the formulation, use, and limitations of the four indices mentioned, providing a perspective on their future development. It establishes the criteria for reliable long-term assessments of thermal and energy environments, encompassing the analysis of both heat and cold strain. Full article

Electrochromic devices (ECDs) in smart buildings have been advanced as a potential solution for improving energy savings and visual and thermal comfort. The current paper is a review of advanced control strategies for ECDs with respect to predictive, environmental, and adaptive strategies for improving building performance. One of the most frequently employed methods is rule-based control (RBC). RBC is being complemented by more sophisticated model predictive control (MPC) and machine learning (ML) procedures. By adjusting ECD behaviour in dynamic response to changing external circumstances, like daylight, glare, temperature, and solar radiation, these improved techniques ensure a major improvement in real-time adaptivity, energy savings, and occupant comfort. The paper systematically examines ECD control techniques available in the literature, detailing performance indicators, energy conservation, and comfort enhancement for various climatic conditions. It also examines hybrid techniques based on MPC and ML models that tackle the obstacles faced by conventional control systems. Furthermore, their compatibility with renewable energy sources such as PV and thermochromic systems is outlined in relation to net-zero energy buildings. The paper ends with a review of future directions that could lead towards standardization in the form of models, sensor networks and AI-based adaptive frameworks to increase the scale as well as the real-world relevance of ECDs in varying building contexts. Full article

As rapid population aging coincides with intensifying urban heat island (UHI) effects, ensuring the outdoor thermal comfort of the elderly in hot–humid regions has become a critical challenge. This study investigates the influence of residential spatial morphology and wind environment on elderly thermal comfort in Fuzhou, China, by integrating PHOENICS and RayMan numerical simulations with a multivariate statistical framework. The Physiological Equivalent Temperature (PET) was calculated across three metabolic intensities (sedentary, walking, and exercising), while the LMG algorithm was used in R to identify the driving mechanisms. Residential layouts are stratified into High-Performance (Group A) and High-Risk (Group B) categories based on their thermal risk. In Group A, the microclimate is convective-dominant wind speed and air changes per hour are the primary determinants of thermal comfort. Conversely, Group B exhibits a radiation-dominant mechanism, with the sky view factor acting as the primary driver of heat stress in confined environments. Furthermore, metabolic intensity emerges as a decisive factor, as physical exercise frequently pushes PET beyond the 37.1 °C threshold even in high-performance layouts. Accordingly, this study proposes differentiated strategies: prioritizing ventilation-led optimization for Group A and radiation-shielding interventions for Group B, while advocating for supplementary active cooling in high-intensity activity zones to safeguard the geriatric population during peak summer heat. Full article

The extensive use of high-resolution digital elevation data, along with continuous improvements in computing power and geographic information system (GIS) tools. Has driven the development of spatial data processing, management, and spatial interpolation methods. This study aims to construct a high-quality spatial distribution map of thermal comfort in densely populated areas of northwestern Jordan using climate data collected from six meteorological stations between 1991 and 2024, based on the indoor temperature index (IAT). To analyze the spatial variability of climate elements, a digital elevation model (DEM) with a spatial resolution of 30 m was used and resampled to a 0.5-km grid. Spatial interpolation employed inverse distance weighting (IDW), with each grid cell using data from the three nearest meteorological stations. The results showed that areas with higher temperatures inside the villas were clearly concentrated in the summer, especially in the lowlands near the Jordan Valley. Indicating that these areas are more susceptible to thermal stress. The model results also show that it performs well in predicting thermal comfort, with a coefficient of determination (R²) between 0.95 and 0.98 and mean squared error (MSE) between 0.35 and 0.50. which reflects the ability of these models to represent the relationship between climate variables and predict thermal comfort levels with a high degree of accuracy. The results indicate significant spatiotemporal differences in thermal comfort within the study area, with longer durations of heat stress in summer. This highlights the importance of combining geospatial methods with numerical simulations in studying the impacts of climate change and supporting urban planning and climate adaptation strategies. Full article

Courtyard-cluster layouts are common in rural public buildings in hot-humid regions, but their open-space types remain poorly quantified. We assessed a completed elderly-care center in Shaoguan, South China, using steady-state RANS CFD (simpleFoam, standard k–ε, OpenFOAM 8), porous-media vegetation, Solar Cal-based mean radiant temperature (MRT), and pedestrian-level Universal Thermal Climate Index (UTCI). Published component-level validation was used to assess toolchain reliability. Simulations represented peak heat stress at noon on 24 July (air temperature 30.3 °C, relative humidity 69%, southwesterly wind 2.9 m/s). Relative to an unobstructed reference (MRT 60.1 °C; UTCI 40.0 °C), architectural open spaces reduced mean MRT by 21.2 °C (35%) and UTCI by 5.3 °C (13%). Covered, laterally open grey spaces were coolest (mean MRT 34.63 °C; UTCI 33.61 °C), whereas open courtyards were warmer (41.79 °C; 35.34 °C) but 18% better ventilated (0.87 versus 0.74 m/s) and served as ventilation nodes. With uniform air temperature and humidity, UTCI variation was strongly associated with MRT (R = 0.989) and weakly with wind speed (R = −0.182). These scenario-bounded results support a shade-first strategy in which courtyards supply ventilation to adjacent covered spaces. Full article

The rapid expansion of high-speed railway networks has increased the operational energy demand and indoor overheating risk of large-scale, high-volume railway station buildings. Natural ventilation is a climate-responsive passive strategy that can improve indoor environmental quality and reduce reliance on mechanical cooling. However, its contribution to the operational sustainability of large transportation buildings remains insufficiently quantified, particularly in hot-summer and cold-winter regions. This study investigates a seasonally adaptive window-opening strategy for Chengdu Station, with particular attention to major functional spaces such as waiting halls and commercial areas. A DesignBuilder model was used to simulate six ventilation scenarios, ranging from doors-only operation to fully open doors and windows. The effects of different window-opening ratios on hourly indoor temperature, relative humidity, adaptive thermal comfort, and annual building energy use were systematically evaluated. The simulation approach was further assessed against field measurements obtained from a comparable large railway station. The results reveal a pronounced nonlinear and seasonal response to the window-opening ratio. In winter, maintaining a very low opening ratio or keeping only the entrance doors open limits unnecessary heat loss. During the transitional seasons, opening ratios of 40–60% are sufficient to remove residual indoor heat while maintaining acceptable thermal conditions. In summer, the marginal improvement in ventilation performance becomes limited when the side-window opening ratio exceeds approximately 80%; therefore, an opening ratio of 80% was selected as a practical operating threshold rather than an absolute thermal optimum. Based on these seasonal characteristics, a month-by-month window-opening strategy was developed. Compared with the doors-only baseline, the proposed strategy reduced the annual high-temperature-hour ratio from 33.4% to 16.36%, corresponding to a decrease of 17.04 percentage points and a relative reduction of approximately 51.0%. Total annual building energy use decreased from 32,238.8 MWh to 25,923.8 MWh, representing an energy saving of 19.6%. These findings demonstrate that seasonally adaptive natural ventilation can simultaneously reduce overheating risk and operational energy demand while maintaining acceptable indoor thermal conditions. The proposed strategy provides a quantitative basis for the sustainable, energy-efficient, and intelligently managed operation of large-space railway stations in hot-summer and cold-winter regions. Full article

Background: Many studies have been carried out using scientific approaches, but the targets are uncertain due to variable environmental and human factors. Therefore, these two factors need to be integrated into modes, which represent combinations of devices in specific statuses. These modes should be changed in response to environmental conditions. To maximize the effectiveness of elemental technologies for environmental consideration, buildings must be designed alongside an operational method based on this mode changing, and the way of describing these operations must also be developed. In this paper, a logic of mode changing is established. The proposed design and operational method can be applied broadly to building design while being adaptable to individual cases. Methods: The design of a house based on the mode-changing theory is presented along with a provisional operational flow as a case study. To support the theory, CFD simulations of each mode’s configuration were conducted for comparison under the representative conditions. These conditions, which represent each mode, can be continuously changed to the other mode by occupants based on their personal comfort. After the house was built, mode-changing operations by the occupants themselves were monitored for a year for the purpose of an operational record. Results: The record of the modes manually selected by occupants, measurements of outdoor/indoor temperatures, and indoor illuminance are superimposed into an integrated graph. According to these records, an actual operational flow was extracted as a method for environmental adjustment. There are notable deviations between the provisional operational flow and the actual record. Based on the actual operational flow, the deviated behaviors are described in the flow, and reasons for the deviation are examined as conscious factors. Conclusions: The deviations from the provisional operational flow demonstrate the flexibility of the mode-changing design, which ultimately enhances occupant satisfaction. Further research is expected to develop a wider variety of modes. The cost analysis of the environmental adjustment devices, human contribution to mode changing, and energy saving ratio are verified as a case study providing a valuable reference for future projects. Full article

Climate change is intensifying heat-related risks in Mediterranean urban environments, increasing the need for pedestrian-scale approaches that combine spatial diagnostics with lived thermal experience. The pilot study develops a three-layer diagnostic framework for assessing outdoor thermal comfort in the central neighbourhoods of Urla, İzmir, Türkiye. The framework integrates UMEP-SOLWEIG microclimatic modelling, citizen science field measurements and structured thermal perception diaries. First, Physiological Equivalent Temperature (PET) and mean radiant temperature (Tmrt) were modelled for 24 November 2023 and used as spatial diagnostic layers to identify three pilot areas with distinct urban morphologies. Second, an independent citizen science thermal walk campaign was conducted on 5 November 2025, during which 12 volunteers recorded in situ air temperature and relative humidity at predefined measurement points. Third, participants completed thermal diaries based on ASHRAE Standard 55 to document thermal sensation, comfort, preference, acceptability and adaptive responses. The modelling and fieldwork components were not designed as same-day validation datasets but as complementary layers for interpreting spatial thermal patterns and perceived thermal conditions. The results show that modelled PET values were relatively homogeneous across the three areas, while field-measured air temperature and subjective thermal responses varied more clearly at the pedestrian scale. These differences suggest that surface conditions, shading, spatial openness and user perception may jointly shape outdoor thermal experience, although the findings should be interpreted as descriptive tendencies due to the single autumn fieldwork session and small sample size. The study contributes a cautious, repeatable pilot framework for linking spatial screening, citizen-generated microclimatic data and structured perception evidence in climate-responsive urban design and local climate governance. Full article

This study quantifies five decades (1975–2025) of residential architectural transformation in Delhi (Tier-I) and Patna (Tier-II), India, among middle-income-group households, and evaluates its implications for passive design loss and mechanical cooling dependence. A stratified survey of 1080 middle-income-group (MIG-I and MIG-II) households across six construction decades documents the systematic elimination of passive features: courtyard presence collapsed from 54.44% (Cohort A, 1975–1985) to 1.39% (Cohort C, 2015–2025); load-bearing masonry declined from 47.78% to 7.78%; and houses lacking passive cooling features quadrupled from 10.83% to 40.83%. Correspondingly, households with three or more air conditioning (AC) units rose from 12.78% (Cohort A) to 33.06% (Cohort C). However, 30–35% of households across all cohorts stated that the ‘indoor temperature remains comfortable without AC’, challenging deterministic AC-dependence assumptions. Regional divergence in drivers is evident: globalization dominates in Delhi (59.24%), while lack of traditional awareness dominates in Patna (39.29%), suggesting hierarchical diffusion and indicating a need for differentiated policy responses. Architectural homogenization shows a consistent association with higher AC ownership and electricity consumption, raising concerns about energy insecurity and climate vulnerability. Hybrid design, integrating traditional passive strategies with contemporary spatial needs, offers a pathway toward climate-resilient urban futures. Full article

Institutional and commercial cooks may experience sustained heat exposure from combustion-based cooking, yet field evidence on thermal conditions following the introduction of electric cooking remains limited. This exploratory before-and-after case study examined three purposively selected kitchens in Kampala, Uganda, combining five-minute temperature and relative humidity monitoring at three spatial positions with cooking diaries, repeated thermal comfort and sensation votes, and enumerator observations. Heat Index (HI) was used as a temperature–humidity screening proxy, and Kampala weather data were used to calculate weather-adjusted differences. On documented active e-cooking days, mean hourly near-stove HI fell from 33.26 °C to 26.00 °C at Site A, 31.35 °C to 29.55 °C at Site B, and 31.71 °C to 27.50 °C at Site C. Time in the Safe HI category increased from 23.5% to 67.8%, 17.0% to 33.3%, and 25.4% to 53.0%, respectively. Day-level tests and a sensitivity analysis using all weather-matched intervention period logger days showed the same overall direction. Raw cooking durations declined for several meals, although, after normalisation by the number of people served, the reductions remained statistically detectable only for Site B breakfast and lunch. The results provide exploratory evidence of lower environmental thermal exposure under documented active e-cooking conditions. Sequential timing, purposive sampling, workload differences, incomplete intervention records and the absence of radiant, air speed and physiological measurements prevent causal interpretation as reduced occupational heat strain. Full article