Search Results (181)

Developing durable multifunctional clothing with enhanced mechanical and comfort properties utilizing eco-friendly, cost-effective hybrid nano finishes is highly challenging. The reason behind the nondurable functionality is the lack of bonding ability of nanoparticles (NPs) with cotton fabric, and this additional coating has a great impact on the mechanical, thermo-physiological, and sensorial comfort properties of cotton fabric. Focusing on these issues, this paper attempts to develop biogenic chitosan-loaded CuO-SiO₂ hybrid nano finishes with three distinct formulations, namely Chi-CuO-SiO_2(5g/L), Chi-CuO-SiO_2(10g/L), and Chi-CuO-SiO_2(20g/L) hybrid nanofluids, to incorporate on cotton fabric by pad-dry-cure method. These hybrid nanofluids from biogenic Chi-CuO and rice husk SiO₂ NPs have been newly introduced for textile application. The NPs CuO and SiO₂ are synthesized from lemon peel zest extract and rice husk, respectively. Characterization of CuO NPs by Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDX), and X-ray diffractometers (XRD) evidences that spherical-shaped, amorphous, and 60–80 nm sized NPs are synthesized. The hydrodynamic performance of hybrid nanofluids measured by Zeta Sizer shows that the chitosan-loaded CuO-SiO_2(5g/L) hybrid nanofluid is the most stable among the three, and the value is +29.4 mV. The presence of CuO NPs, SiO₂ NPs, and chitosan on cotton fabric was confirmed by FTIR, FESEM, and EDX spectra of the hybrid nanofluid-deposited fabric. The cotton fabric coated with chitosan-loaded CuO-SiO₂ hybrid nanofluids exhibits better durable antimicrobial efficacy, UV-protective properties, and thermo-physiological comfort properties than that of the uncoated fabric. More specifically, CuO-SiO_2(20g/L)-coated fabric demonstrates approximately 99.99% bacterial efficacy against both gram-positive and gram-negative bacteria even after 15 washing cycles, and excellent UV-protective properties. In addition, CuO-SiO_2(5g/L)-coated fabric displays around 75% enhancement of overall moisture management properties and 1.22% and 0.53% enhancement of tensile strength in warp and weft directions with excellent elongation compared to the pristine one. Moreover, assessment of the mechanical sensorial comfort properties of this fabric depicts that it is smoother, and has better thermal conductivity than that of the control one. In addition, CuO-SiO_2(5g/L) hybrid nanofluid-treated cotton fabric exhibited cell viability above 95%, which confirms its non-cytotoxicity. The outcomes of this study suggest that chitosan-loaded CuO-SiO_2(5g/L) hybrid nanofluid-treated cotton fabric can be considered as optimum and employed as biomedical textiles with better mechanical and comfort properties. Full article

Thermal comfort shapes occupant health, well-being, and productivity and influences the sustainability and energy efficiency of the built environment. The Predicted Mean Vote (PMV) is the most widely used thermal comfort index, yet four of its six input parameters—globe temperature, clothing insulation, metabolic rate, and air velocity—require specialized, costly equipment or occupant self-reporting, which has long limited its practical large-scale application. This study introduces a machine learning (ML) framework aimed at estimating these four parameters using indoor and outdoor air temperature and relative humidity as its only sensor inputs, complemented by readily available contextual information and individual activity profiles. It exploits the climatic coupling of globe temperature and air velocity to the indoor–outdoor environment and the temperature- and activity-driven behavioral patterns that govern clothing insulation and metabolic rate. The proposed framework achieved strong predictive performance, explaining 85% of the variance in actual PMV values (R² = 0.85), with a near-zero mean residual (−0.041) and a residual standard deviation of 0.286. Approximately 91% of absolute errors fell below 0.5 PMV units—a deviation unlikely to shift the assigned thermal comfort category. Mapped to thermal comfort categories, predictions reached 80% accuracy, with a macro-averaged precision of 0.81 and recall of 0.80, exhibiting the highest performance for neutral and warm conditions while performing less accurately for cool discomfort. These results suggest that standard temperature and humidity sensors, combined with basic contextual information and individual activity profiles, could support reliable PMV-based thermal comfort assessment, advancing scalable, sensor-light comfort monitoring for energy-efficient, sustainable buildings. Full article

Improving HVAC energy efficiency while maintaining collective thermal comfort remains challenging in multi-occupant shared indoor environments, where occupants differ in thermal sensation, activity level, clothing condition, and spatial distribution. This study develops and field-validates an integrated edge-cloud IoT framework that connects non-invasive occupant-state sensing, INT8 edge thermal-sensation inference, and group-comfort-oriented HVAC setpoint optimization for classroom-based shared spaces. The proposed system integrates localized temperature–humidity sensing, vision-derived occupancy, posture, and clothing estimation, cloud-based thermal sensation model training, and edge-deployed real-time control on a HUB 8735 ULTRA device. A 4-day model-training data collection campaign with structured questionnaires was first conducted to obtain occupants’ Thermal Sensation Votes (TSVs) as ground-truth labels. The trained model was compressed from Float32 to INT8 through post-training quantization and deployed on the edge device for real-time inference. Predicted individual TSV values were then transformed into a PPD-inspired TSV-derived dissatisfaction index and used to determine the HVAC setpoint through rolling-horizon group comfort optimization. A separate eight-school-day single-blind daily-block A/B field validation was conducted, with four validation days assigned to the proposed smart control strategy and four days assigned to a fixed 25 °C baseline. The validation dataset included 2194 valid TSV questionnaire responses, which were aggregated into 116 valid 30 min classroom sessions for statistical comparison. The proposed control achieved a session-level mean TSV of −0.13, compared with −0.66 under the baseline, with Welch’s t(100) = 11.2, p < 0.001 and Cohen’s d = 2.11. Daily HVAC energy use decreased from 2.61 to 2.32 kWh/day, corresponding to a cumulative reduction of 1.16 kWh, or 11.1%, over the validation period. These results support the short-term feasibility of the proposed classroom-level human-centric HVAC control framework. However, because the validation was limited to a short-term classroom setting without full weather/load normalization, longer multi-season and multi-room studies are required to further evaluate generalizability and long-term energy performance. Full article

Winter underuse of urban parks in severe-cold cities limits year-round outdoor activity, especially for cold-sensitive users. This study developed a comfort–risk–adaptation framework integrating thermal perception, model-estimated cold-stress risk, and behavioral responses. Field microclimate measurements and synchronous questionnaires were conducted in Nanhu Park, Changchun, China, under clear winter conditions, yielding 386 paired human–environment samples. The Universal Thermal Climate Index (UTCI), Required Clothing Insulation (IREQ), wind chill temperature (WCT), and contact cooling indicators were used to quantify thermal exposure and cold-stress risk. Results showed significant spatial differences in wind speed, solar radiation, mean radiant temperature, and UTCI, while air temperature and humidity varied little. The neutral UTCI was 3.14 °C (unweighted) and 3.70 °C (weighted), and the 80% thermal acceptability threshold was −15.24 °C (95% CI: −16.14 to −14.22 °C). Despite acceptable thermal perception, physiological cold-stress risks remained under certain conditions. The findings highlight the need to integrate solar access, wind mitigation, low-conductivity materials, and moderate activity routes to improve winter usability in severe-cold urban parks. Results are condition-specific and reflect observed users under clear to partly cloudy winter daytime conditions rather than universal thresholds. Full article

Driven by the demand for high-quality housing, fourth-generation residential buildings—known internationally as “Vertical Forest” and in China as “Urban Forest Garden”—have developed rapidly. Initially built in mild southern regions, they have recently expanded to colder northern areas, with over 50 projects underway in provinces such as Shanxi, Hebei, Shaanxi, and Gansu. Several cities have introduced design standards and incentives, and the China Association for Standardization of Engineering Construction has issued the “Design Standards for Urban Forest Garden Housing.” However, in cold regions, where winters are long and cold and summers are short and hot, there is a lack of systematic quantitative research on how balcony design affects building carbon reduction, energy efficiency, and indoor thermal comfort. To address this research gap, this paper poses the following research questions: (1) In fourth-generation residential buildings in cold regions, how do different combinations of balcony orientations affect annual energy consumption and indoor thermal comfort? (2) Which balcony configurations offer the best balance between carbon reduction, energy efficiency, and thermal comfort? Based on statistical analysis of terrace configurations from more than 40 projects, 12 typical configuration models were identified. Using Ladybug and Honeybee tools on the Grasshopper platform, building energy consumption and indoor thermal comfort were simulated. Multi-objective trade-off analysis was performed using the Pareto front method. In this study, indoor thermal comfort was evaluated using the PMV (Predicted Mean Vote) index. PMV is an index proposed by Professor Fanger that comprehensively reflects human thermal sensation, taking into account air temperature, humidity, wind speed, mean radiant temperature, human metabolic rate, and clothing thermal resistance. Its typical range is −3 (cold) to +3 (hot); in this study, the comfort zone was defined as −1 ≤ PMV ≤ 1. Key findings: (1) The southwest + south terrace configuration shows the highest annual energy consumption, exceeding the lowest (northwest + west) by 2.7%, indicating that south-facing terraces are less favorable for carbon reduction. (2) The best thermal comfort is achieved with east, west, and south orientations. Compared to the least comfortable combination (southwest + northwest), the difference in PMV comfort percentage reaches 2.4%. (3) The Pareto front reveals that beyond a certain comfort level, energy consumption increases sharply. The west + south and east + south combinations yield the highest thermal comfort (49.4%) while maintaining relatively low energy consumption (17.98 kWh/m²). Therefore, in cold regions, fourth-generation residential designs should prioritize terrace combinations integrating south-facing and side-facing orientations and avoid pure corner configurations to balance winter solar gain and summer shading. Full article

Balancing energy efficiency and wearer thermal comfort in cold environments remains a critical challenge for wearable heating systems. Commercial graphene-film heating pads, consisting of a graphene film sandwiched between cotton-gauze layers, provide a flexible heating platform; however, the effects of temporal power-modulation strategies on physiological responses, subjective thermal perception, and energy use remain insufficiently understood. Using identical heating elements and fixed heating locations, this study evaluated three intermittent heating strategies for electrically heated garments: (i) a descending-step protocol (IP-1), (ii) alternating dual-power heating (IP-2), and (iii) periodic ON/OFF cycling (IP-3). Ten healthy male participants completed five randomized experimental conditions, including continuous heating (CP) and no heating (NH), during 60 min of exposure at −5 °C. Mean skin and torso temperatures, together with subjective thermal sensation, comfort, and preference, were assessed. Compared with IP-3, IP-1 and IP-2 maintained significantly higher mean skin temperatures from 15 to 60 min (p < 0.05), while their subjective responses remained closer to thermal neutrality. CP produced the strongest local warming but resulted in excessive warmth in the directly heated torso regions, whereas IP-3 provided insufficient thermal compensation. IP-1 achieved the most favorable comfort–efficiency balance, maintaining torso warmth and acceptable subjective responses while reducing energy use by approximately 46% relative to CP. These findings indicate that the transition characteristics and continuity of power delivery, rather than heating duration alone, are critical for optimizing thermal comfort and energy efficiency in wearable heating systems. Full article

It is well-known that high-performance thermal protective clothing is crucial for personnel working in high-temperature environments, such as firefighters. Thermal protective clothing design usually integrates textile materials’ type, thickness, physical and chemical properties (such as thermal conductivity), ergonomics, and environmental adaptability. In this study, the heat transfer process and the optimal thickness are mainly discussed for providing some references on the design of this clothing. The thickness design of thermal protective clothing fabrics is carried out via numerical heat transfer simulations based on experimental data obtained from manikin tests. Firstly, one heat transfer model for thermal protective clothing, including three textile materials’ layers and one air layer, is constructed according to Fourier’s law of heat conduction, Newton’s law of cooling, and the Stefan–Boltzmann law, with appropriate boundary conditions assigned. Secondly, the finite volume element method, which has the important advantage of preserving conservation properties for physical quantities, is employed to discretize the heat transfer model. Thirdly, the convective heat transfer coefficient, which characterizes heat exchange between fluid and solid surfaces, is determined approximately by the least-squares method based on the given data, while the heat transfer process is simultaneously simulated. Fourthly, the thicknesses of the second and fourth layers are critical to the performance of thermal protective clothing. Two optimization algorithms are proposed to determine the optimal thickness configuration that effectively balances thermal insulation and wearing comfort. From the above results, it is recommended to use multilayer textile composite materials incorporating aerogel insulation layers and phase-change material interlayers. Full article

The South-to-North Water Diversion Project (SNWDP) in China involves a vast number of resettlers with far-reaching impacts. As a crucial carrier of resettlers’ daily lives, the indoor thermal comfort of resettlement housing directly affects their physical and mental health. However, existing empirical and field studies have paid limited attention to the thermal comfort and thermal adaptation of the resettlers. This study focuses on resettlers of the SNWDP, employing a combination of questionnaires and on-site measurements to analyze thermal benchmarks and thermal adaptation behavior data. The study introduces the concept of relative deprivation theory from social psychology, compares the correlations between vertical and horizontal deprivation and thermal perception across different relocation modes, and validates the predictive performance of commonly used thermal comfort models. The results show that as the relocation distance increases, the summer indoor thermal neutral temperature rises sequentially, and both the sensitivity to temperature changes and the width of the comfort zone also increase. Regarding thermal adaptation behaviors, the short-distance group primarily relies on passive adjustments such as using electric fans and reducing clothing, while the long-distance group significantly shifts toward active mechanical cooling like air conditioning. The sense of relative deprivation has a significant impact on the thermal comfort of medium- and long-distance resettlers, and its correlation even exceeds that of physical factors such as air temperature and black globe temperature. Among all groups, the ePMV and ePTS models modified by the expectancy factor exhibit the best predictive performance, with the smallest average deviation from the actual Thermal Sensation Vote (TSV), making them the optimal evaluation models for indoor thermal comfort of resettlers in the SNWDP. The findings provide theoretical guidance for creating healthy and comfortable indoor thermal environments in resettlement areas and for the sustainable development of subsequent phases of the SNWDP. Full article

Outdoor thermal comfort models are generally developed for healthy populations and may not be directly applicable to patients with altered thermoregulatory capacity. This study examined summer outdoor thermal responses of lung cancer patients in Shenyang, China, focusing on differences by treatment modality and disease stage. Field microclimatic measurements and questionnaire surveys were conducted in four typical outdoor microenvironments: waterfront place, tree-shaded space, open square, and enclosed porch. A total of 706 lung cancer patients were surveyed and stratified by treatment modality and disease stage. Physiologically equivalent temperature (PET) was calculated using RayMan Pro based on measured air temperature, mean radiant temperature, air velocity, relative humidity, clothing insulation, and activity-based metabolic rate. Subgroup differences were observed in neutral PET and thermal comfort ranges. Chemotherapy patients had the highest neutral PET at 26.0 °C, while immunotherapy patients had the lowest at 22.6 °C. Radiotherapy, surgery, and targeted therapy groups showed neutral PET values of 23.3 °C, 23.7 °C, and 24.5 °C, respectively. Early-stage patients had a neutral PET of 23.8 °C, whereas late-stage patients showed a higher value of 25.8 °C and a narrower neutral range of 23.1–28.5 °C. The surgery group had a broad acceptable PET range of 20.5–28.6 °C, while the late-stage group had a narrower range of 24.7–26.8 °C. Preferred temperature was also higher in the chemotherapy and late-stage groups. These findings indicate heterogeneous summer outdoor thermal responses among lung cancer patients and provide empirical evidence for subgroup-sensitive thermal assessment and outdoor space design near healthcare facilities. Full article

Elderly individuals in rural China are highly vulnerable to extreme weather events and temperature fluctuations due to inadequate infrastructure in the built environment and constrained economic conditions, thereby increasing their health risks. Outdoor spaces represent one of the primary daily activity settings for rural older adults. However, existing research rarely links spatiotemporal patterns of outdoor activities to evidence-based thermal environment optimization, leaving a critical knowledge gap for age-friendly and sustainable rural design. This study focuses on the spatiotemporal differentiation patterns of daily outdoor activities among elderly people aged 60 years and above in rural Xi’an, as well as the optimization of spatial variations in thermal environments. Using on-site interviews, thermal environment measurements, thermal comfort questionnaires, continuous thermal environment monitoring, and machine learning based on random forest, this study drew the following conclusions: (1) outdoor activities in winter were concentrated between 9:00–11:00 and 13:00–17:00, while in summer, they shifted to the morning and evening periods, namely 6:00–9:00 and 17:00–21:00. (2) Models for outdoor clothing adjustment, thermal sensation, and thermal acceptability among elderly residents were established. The calculated neutral temperature was 10.19 °C, with a 90% outdoor thermal acceptability range of 9.6–27.2 °C and an 80% outdoor thermal acceptability range of 6.2–30.6 °C. These findings differ from those documented in regions with distinct climate zones and geographical settings. This discrepancy stems from regional climatic features, lifestyle variations between urban and rural older adults, and differences in the thermal environment quality of elderly-oriented outdoor activity spaces. (3) In winter, the acceptable period of the Universal Thermal Climate Index (UTCI) at south-facing entrances (10:30–16:30) was significantly longer than that in the courtyard (13:30–14:00). In summer, the comfortable period in the courtyard (before 10:00 and after 20:00) was longer than that at north-facing entrances (before 09:00). A random forest model for thermal sensation was established, and the relative importance of each parameter influencing thermal sensation was analyzed. On this basis, priority improvement pathways and strategies for the thermal environment, as well as suggestions for the subjective adaptive behaviors of elderly residents, were proposed. The research results of this study can provide technical solutions for age-friendly thermal environment design in rural areas, thereby safeguarding the comfort, health, and social well-being of the elderly population in rural areas. Full article

Bird feathers possess functions such as water resistance, thermal insulation, and air permeability, providing inspiration for the design of functional fabrics. Based on the functional differentiation of different feather regions and the structural constraints associated with these functions, this study selected down feathers, feather vanes, hooklets, and fluffy feather filament node structures as biomimetic prototypes. Four biomimetic knitted structures were designed for outdoor environments with significant temperature fluctuations and for the thermo-moisture comfort needs of older adults. Through macro- and micro-structural feature extraction, three-dimensional modeling, and experimental testing, a multi-parameter evaluation system covering water resistance, thermal resistance, thermal insulation rate, air permeability, moisture vapor transmission, and moisture management was established to systematically evaluate the thermo-moisture regulation performance of the fabrics. The results showed that each structure exhibited distinct performance advantages: Structure 1 demonstrated the best thermal insulation performance; Structure 2 showed relatively superior water resistance and outstanding air permeability; Structure 4 exhibited relatively superior moisture vapor transmission and moisture management performance; and Structure 3 achieved the highest gray relational optimality value, indicating a relatively balanced thermo-moisture regulation capability. Among all performance indicators, air permeability showed the highest correlation with the knitted structures. Based on these results, and considering regional differences in heat generation and sweating across different body parts of older adults, this study further explored zonal application strategies for elderly outdoor clothing to improve wearing comfort and functionality under environments with fluctuating thermal conditions. Full article

Thermal comfort in operating rooms is critical for staff performance and safety, but conflicting requirements among professional groups create complex challenges. In a real operating room with a unidirectional airflow system, air velocity and temperature were measured, and predicted thermal sensation as well as the proportion of dissatisfied staff were calculated according to international standards. Analyses included surgeons, technical assistants, and anesthesiologists, considering clothing insulation, task-specific activity, gender, body mass index, and the use of lead aprons of different weights. Gender, body mass index, and temperature strongly influenced thermal comfort, whereas variation in air velocity had only minor effects. Thermal comfort targets diverged markedly between professional groups. Under identical conditions in our operating room, up to 75% of male surgeons wearing lead aprons experienced pronounced heat stress, whereas approximately 22% of female anesthesiologists experienced predominantly cold discomfort. Female surgeons would require temperatures as low as 16 °C to achieve thermal comfort, while nearly 50% of male surgeons perceived even this temperature as uncomfortably warm. Removing lead aprons reduced heat stress in surgeons but increased cold stress in anesthesiologists. Higher body-mass index improved heat dissipation in surgeons but aggravated cold stress in anesthesiologists. These findings demonstrate that uniform temperature settings cannot ensure thermal comfort for all professional groups. Practical implications include the need for role-specific strategies, such as targeted personal cooling or warming measures and differentiated clothing systems, to improve working conditions and maintain patient safety in operating rooms. Full article

In order to design suitable heat-dissipating clothing for people engaged in high-temperature conditions, the vapor-dominated moisture transfer and heat dissipation properties of polyester fabric (Coolmax) with irregular cross-section in sweat-wicking protective clothing were analyzed by establishing a three-dimensional thermal–moisture coupled numerical model. In this study, moisture transport was mainly considered as water vapor transport within the porous fabric domain under a prescribed vapor-input boundary condition, rather than as a complete liquid-sweat-wicking, condensation, and re-evaporation process. The effects of convective heat transfer coefficient, ambient temperature, fabric thickness, and porosity on the thermal and moisture regulation behavior of the fabric were analyzed. The results show that Coolmax fabric can realize more efficient vapor transfer and heat diffusion under different ambient conditions due to its irregular grooved fiber structure, and its skin-side temperature is lower, and the relative-humidity distribution is more uniform than that of cotton material. Through the comparative analysis of temperature and relative humidity under different parameter combinations, the reasonable structural parameter range considering heat dissipation efficiency and perspiration ability is determined as follows: a fabric thickness of 0.8–1.2 mm and a porosity of 0.70–0.80, which can effectively improve the heat and moisture regulation performance of fabrics. This study provides a theoretical basis and numerical simulation reference for material selection and structure design of sweat-protective clothing and functional sportswear, which is helpful to improve wearing comfort and reduce thermal stress. Full article

Heating, ventilation, and air conditioning (HVAC) systems struggle to maintain optimal thermal comfort because perception is subjective and varies significantly across individuals. Traditional uniform cooling strategies often overlook demographic diversity, leading to inequitable comfort outcomes and inefficient building operations. To address this limitation, this study analyzed a web-based survey of 366 university occupants using a partial proportional odds model with multiple imputation and inverse-frequency weighting. Interaction terms, specifically Age–Activity, Gender–Clothing, and Age–Clothing, were included to assess combined effects that reflect demographic disparities in adaptive capacity. The results show that clothing insulation, activity, age, gender, race/ethnicity, and space type significantly influence thermal responses. Notably, male occupants were more than three times as likely to report feeling too warm (odds ratio [OR] = 3.24), whereas older adults exhibited significantly lower odds of reporting feeling too warm (OR = 0.42). Substantial variation was observed across racial and ethnic groups (ORs ranging from 2.4 to 6.5). These findings highlight the limitations of traditional population-average comfort approaches and provide valuable scientific insights for demand-response-ready HVAC strategies that adjust temperature setpoints dynamically without sacrificing comfort. By offering accurate, real-time estimates across diverse thermal ranges, these occupant-centric models reduce HVAC energy use and associated emissions at the building scale while supporting ancillary services for flexible load shifting and smarter coordination within low-carbon electric grids. Ultimately, incorporating demographic and contextual diversity into building controls reduces unnecessary cooling waste while promoting thermal equity, establishing a human-centric foundation for sustainable built environments. Full article

This study examines the gap concerning occupants’ perceived thermal comfort and objectively measured indoor conditions in a green university building in Riyadh. The purpose is to assess occupant satisfaction with thermal conditions, compare subjective responses with physical measurements, and derive design and operational implications for educational buildings in hot-arid climates. The primary aim was to assess occupant satisfaction with indoor thermal conditions and to measure key environmental parameters to provide a thorough assessment of thermal comfort. A cross-sectional approach was used, combining subjective data from the Center for the Built Environment (CBE) Occupant Indoor Environmental Quality (IEQ) survey with objective measurements of air temperature, relative humidity, mean radiant temperature, and air velocity, which were documented over five consecutive working days during the mid-winter period in Riyadh. These parameters were explored using the CBE Thermal Comfort Tool to calculate Predicted Mean Vote (PMV) and Predicted Percentage Dissatisfied (PPD) indices. Statistical analyses examined the relationship between occupant-reported comfort and measured environmental conditions. Results showed that only 36% of occupants reported satisfaction with thermal comfort, while 48% expressed dissatisfaction. In contrast, objective measurements indicated stable indoor conditions within recommended comfort ranges (average temperature 23 °C, humidity 30–34%, MRT 24 °C, air velocity 0.5–1.0 m/s), with PMV values near neutral (−0.2 to 0.0) and PPD below 6%. The observed discrepancy highlights the influence of regional climate, individual adaptability, and perceived control. These findings emphasize the need to integrate both subjective feedback and objective measurements to develop occupant-centered strategies that enhance comfort and well-being in sustainable educational buildings in hot-arid climates. Full article