Search Results (103)

This study presents the design and fabrication of a glass fiber–poplar veneer composite plate, investigating how varying interlayer configurations of glass fiber (single- and double-layer) and the arrangement of poplar veneer layers (odd and even) impact the mechanical and thermal insulation characteristics of these composite plates. Compared to plywood made from natural wood, glass fiber significantly improved the properties of fast-growing poplar plywood. The highest impact strength increased by 3.62 times, while the flexural strength increased by 26.22% and the tensile strength by 29.66%. The thermal diffusion coefficient of the experimental group decreased by 40.74%, indicating better insulation. Interestingly, single-layer glass fiber is superior to a double-layer structure in terms of thermal insulation. An optimal interlayer structure was identified, comprising one veneer layer between two layers of glass fiber cloth, repeated three times. Abaqus 2019 was used for finite element analysis (FEA). The simulation results agree with the experimental data to within 5%. These findings confirm the importance of structural configuration in determining the properties of composite materials, providing a theoretical basis for the structural design of fiber–reinforced composite materials. Full article

Sheep wool is a natural fiber from various sheep breeds, mainly used in clothing for its insulation properties. It makes up a small share of global fiber production, which is declining as synthetic fibers replace wool and meat farming becomes more profitable. Wool from slaughter sheep, often unsuitable for textiles, is treated as biodegradable waste. The aim of the study was to develop a fully biodegradable composite of natural origin from a polylactide (PLA) matrix reinforced with sheep wool and to select the optimal modifications (chemical) of sheep wool fibers to obtain modified properties, including mechanical properties. The behavior of the composites after exposure to aging conditions simulating naturally occurring stimuli causing biodegradation and thus changes in the material’s performance over its lifespan was also examined. Dynamic thermal analysis was used to describe and parameterize the obtained data and their variables, and the mechanical properties were investigated. The research culminated in a microscopic analysis along with changes in surface properties. The study demonstrated that wool-reinforced composites exhibited significantly improved resistance to UV degradation compared to pure PLA, with samples containing 15% unmodified wool showing a 54% increase in storage modulus at 0 °C after aging. Chemical modifications using nitric acid, iron compounds, and tar were successfully implemented to enhance fiber–matrix compatibility, resulting in increased glass transition temperatures and modified mechanical properties. Although wool fiber is not a good choice for modifications to increase mechanical strength, adding wool fiber does not improve mechanical properties but also does not worsen them much. Wool fibers are a good filler that accelerates degradation and are also a waste, which reduces the potential costs of producing such a biocomposite. The research established that these biocomposites maintain sufficient mechanical properties for packaging applications while offering better environmental resistance than pure polylactide, contributing to the development of circular economy solutions for agricultural waste valorization. So far, no studies have been conducted in the literature on the influence of sheep wool and its modified versions on the mechanical properties and the influence of modification on the degradation rate of PLA/sheep wool biocomposites. Full article

Advancements in thermoregulating textiles have been propelled by innovations in nanotechnology, composite materials, and smart fiber engineering. This article reviews recent scholarly papers on experimental passive and active thermoregulating textiles to present the latest advancements in these fabrics, their mechanisms of thermoregulation, and their feasibility for use. The review underscores that phase-change materials enhanced with graphene, boron nitride, and carbon nanofibers offer superior thermal conductivity, phase stability, and flexibility, making them ideal for wearable applications. Shape-stabilized phase-change materials and aerogel-infused fibers have shown promising results in outdoor, industrial, and emergency settings due to their durability and high insulation efficiency. Radiative cooling textiles, engineered with hierarchical nanostructures and Janus wettability, demonstrate passive temperature regulation through selective solar reflection and infrared emission, achieving substantial cooling effects without external energy input. Thermo-responsive, shape-memory materials, and moisture-sensitive polymers enable dynamic insulation and actuation. Liquid-cooling garments and thermoelectric hybrids deliver precise temperature control but face challenges in portability and power consumption. While thermoregulating textiles show promise, the main challenges include achieving scalable manufacturing, ensuring material flexibility, and integrating multiple functions without sacrificing comfort. Future research should focus on hybrid systems combining passive and active mechanisms, user-centric wearability studies, and cost-effective fabrication methods. These innovations hold significant potential for applications in extreme environments, athletic wear, military uniforms, and smart clothing, contributing to energy efficiency, health, and comfort in a warming climate. Full article

Indoor environmental quality profoundly impacts student learning outcomes and teacher effectiveness, particularly in primary education, where children spend most of their developmental years. The study compares the New Zealand Ministry of Education’s Designing Quality Learning Spaces (DQLS) version 2.0 for primary school classrooms with international standards set by OECD countries to develop IAQ and thermal comfort best practices in New Zealand across six climate zones. The research evaluates indoor air quality (IAQ) and thermal comfort factors affecting students’ and teachers’ health and performance. Using Ladybug and Honeybee plugin tools in Grasshopper with Energy Plus, integrated into Rhino 7 software, the study employed advanced building optimisation methods, using multi-criteria optimisation and parametric modelling. This approach enabled a comprehensive analysis of building envelope parameters for historical classroom designs, the Avalon block (constructed between 1955 and 2000). Optimise window-to-wall ratios, ceiling heights, window placement, insulation values (R-values), clothing insulation (Clo), and window opening schedules. Our findings demonstrate that strategic modifications to the building envelope can significantly improve occupant comfort and energy performance. Specifically, increasing ceiling height by 0.8 m, raising windows by 0.3 m vertically, and reducing the window-to-wall ratio to 25% created optimal conditions across multiple performance criteria. These targeted adjustments improved adaptive thermal comfort, ventilation, carbon dioxide, and energy efficiency while maintaining local and international standards. The implications of the findings extend beyond the studied classrooms, offering evidence-based strategies for overall design and building performance guidelines in educational facilities. This research demonstrates the efficacy of applying computational design optimisation during early design phases, providing policymakers and architects with practical solutions that could inform future revisions of New Zealand’s school design standards and align them more closely with international best practices for educational environments. Full article

The climate of the Hungarian lowland (Central European region, Pannonian Plain area) can be characterized by Köppen’s Cfb climate formula (C—warm temperate, f—no seasonality in the annual course of precipitation, b—warm summer). This characterization does not provide information about the human thermal load and thermal perception. The aim of this work is to fill this gap. We focused on the morning, clear-sky periods of the day, when the heat supply provided by the weather is the lowest. The human thermal load of clear-sky mornings was estimated using the new clothing thermal resistance–operative temperature (r_cl–T_o) model. In contrast to IREQ-type (Required Clothing Insulation) models, this model parametrizes the total metabolic heat flux density (M) as a function of anthropometric data (body mass, height, sex, age). In the simulations, the selected persons walk (M values range between 135 and 170 W m⁻²) or stand (M values range between 84 and 96 W m⁻²), while their body mass index (BMI) varies between 25 and 37 kg m⁻². The following main results should be highlighted: (1) Human activity has a significant impact on r_cl; it ranges between 0 and 3.5 clo during walking and between 0 and 6.7 clo during standing. (2) The interpersonal variability of r_cl increases with increasing heat deficit accordingly; in the case of a walking person, it is around 1 clo in the largest heat deficits and around 0 clo in the smallest heat deficits. Since, in general, anticyclones increase the heat deficit while cyclones reduce it, extreme thermal loads are associated with anticyclones. It should be mentioned that the interpersonal variability of the human thermal load cannot be analyzed without databases containing people’s anthropometric data. Full article

Local data about indoor thermal comfort are in short supply, which are always different from the predicted results produced by models shown in previous studies. Shopping malls that consume substantial energy need to save energy, provided that thermal comfort is maintained. Therefore, this research investigated indoor thermal comfort using field measurements and questionnaires in a typical shopping mall in Danyang, China, with a hot summer and cold winter climate in order to explore local demands and energy-saving potential. The findings are as follows: (1) The average air temperature ($T_a$) and operative temperature ($T_{op}$) are 26.7 °C and 26.4 °C, which implies a minor influence from radiation and other factors on $T_a$. Women are more sensitive to changes in outdoor temperature since clothing insulation ($I_{cl}$) varies by gender: 0.31 clo and 0.36 clo for male and female individuals, respectively. (2) The thermal neutral temperature (TNT) derived from the thermal sensation vote (TSV) is 25.26 °C, which is significantly higher than the 21.77 °C obtained from the predicted mean vote (PMV) model. (3) There is a wide range of acceptable temperatures for thermal comfort because the highest temperature was identified by the thermal comfort vote (TCV) at 27.55 °C, followed closely by 27.48 °C, 26.78 °C, and 25.32 °C, which were separately derived from the thermal acceptance vote (TAV), TSV, and predicted percentage of dissatisfied (PPD) people; these were based on an upper limit of the acceptable 80% range. (4) In total, 94.85% of respondents accepted the indoor air quality, although the median concentration of CO₂ was 772 ppm, and the neutral relative humidity level was 70.60%. Meanwhile, there is an important relationship between air quality satisfaction and operative temperature; thus, the temperature (26.93 °C) with peak satisfaction can enhance air quality perception and thermal comfort. (5) The energy savings that can be achieved are 25.77% and 9.12% at most based on acceptable thermal comfort compared with baseline energy consumption at 23 °C and 26 °C, respectively. Full article

Thermal insulation is a basic property for describing a set of clothing and consists of the thermal resistance of the individual layers of clothing (which depends on the material used and its structure) and also takes into account the air gaps between the layers. Here, the total thermal insulation was measured in a climatic chamber with a thermal manikin. The air gaps were measured using a 3D scanning technique and calculated using the Blender 3D graphics program. Our study shows the effect of size (fit) on the size of the air gaps, as well as the influence of the air gap size on the thermal insulation value (both for static and dynamic conditions with 45 double steps and 45 double arm movements per minute) for workwear. The relationship of the total thermal insulation value on the volume and size of the air gap was described as a second-order polynomial (R2 > 0.8). It was observed that for workwear, thermal insulation did not increase when the air gaps exceeded approximately 30 mm or when the air gap volume reached 50–55 dm³. The highest total thermal insulation (~0.23 m²°C/W) was achieved when the garment closely fitted the wearer’s body (or in this case, the thermal manikin) without excessive tightness. Full article

As global climate change intensifies, the frequency and severity of extreme weather events continue to rise. However, research on semi-outdoor and transitional spaces remains limited, and transportation stations are typically not fully enclosed. Therefore, it is crucial to gain a deeper understanding of the environmental needs of users in these spaces. This study employs machine learning (ML) algorithms and the SHAP (SHapley Additive exPlanations) methodology to identify and rank the critical factors influencing outdoor thermal comfort at tram stations. We collected microclimatic data from tram stations in Guangzhou, along with passenger comfort feedback, to construct a comprehensive dataset encompassing environmental parameters, individual perceptions, and design characteristics. A variety of ML models, including Extreme Gradient Boosting (XGB), Light Gradient Boosting Machine (LightGBM), Categorical Boosting (CatBoost), Random Forest (RF), and K-Nearest Neighbors (KNNs), were trained and validated, with SHAP analysis facilitating the ranking of significant factors. The results indicate that the LightGBM and CatBoost models performed exceptionally well, identifying key determinants such as relative humidity (RH), outdoor air temperature (Ta), mean radiant temperature (Tmrt), clothing insulation (Clo), gender, age, body mass index (BMI), and the location of the space occupied in the past 20 min prior to waiting (SOP20). Notably, the significance of physical parameters surpassed that of physiological and behavioral factors. This research provides clear strategic guidance for urban planners, public transport managers, and designers to enhance thermal comfort at tram stations while offering a data-driven approach to optimizing outdoor spaces and promoting sustainable urban development. Full article

This study conducted a within-subject study to assess sleeping environmental comfort, acceptance, and self-reported sleep quality in air-conditioned and mixed-mode ventilated bedrooms in a subtropical region during the summer. A wide thermal comfort temperature range of 22.2 °C to 28.2 °C was observed, with slightly warmer thermal sensation at higher temperatures but no significant differences in sleep quality or environmental comfort acceptance within this range. Subjects adapted to warmer sleeping conditions by choosing lighter clothing and bedding insulation. Energy simulations indicated a reduction in the percentage of nights requiring cooling from 65% to 23% by increasing the set-point temperature from 22 °C to 28 °C, resulting in a potential 95% savings in cooling energy. This study advocates for an economical and energy-efficient approach to enhance sleeping thermal comfort while reducing cooling energy usage. These findings offer valuable insights for improved residential building design and optimized cooling energy management practices, especially in light of intensified climate change and the imperative for behavioral changes to promote building sustainability. Full article

Due to constantly shifting environmental and personal circumstances, humans have a wide range of thermal comfort needs. Cold intolerance (CI) is a personalized thermoregulation disorder characterized by a persistently cold-feeling problem, regardless of weather conditions. Improvements in clothing thermal comfort can help maintain proper insulation levels, hence reducing excess heat loss brought on by thermoregulation disorders since the wearer’s thermal comfort is impacted by controllable environmental and personal factors. Despite extensive research on cold-proof clothing, no studies have examined the current status of cold protective clothing systems when taking individual considerations into account, particularly those who use them and have cold sensitivity. There is a significant study gap in research on cold intolerance discomfort and advancements in appropriate cold protection apparel applied to individuals with thermoregulation disorders. Accordingly, this paper reviews the occurrence and severity of cold intolerance and its comfort challenges. It also addresses recent developments in cold protective clothing design, aimed at opening pathways for further investigation into adopting this cutting-edge technology for cold intolerance wear design. This review also aims to clarify the existing opportunities for enhancing the thermal insulation capabilities and other comfort factors of cold protection apparel, which are conducted during the stages of garment design and clothing material/textile manufacture. A thorough assessment of the research on introducing novel surface finishing methods in the pretreatment section and modifying the structural properties of garment materials at the fiber/yarn or weaving stage is conducted. Furthermore, we systematically discuss the potential design solutions regarding fit and size as well as stitching technologies during garment development for thermal insulation enhancement of cold protective clothing design. Full article

Thermal comfort in buildings is essential for occupant well-being and energy efficiency, particularly in naturally ventilated environments where indoor conditions are closely influenced by outdoor climates. Current studies have not fully explored how thermal comfort varies across regions with similar climatic classifications but distinct geographic and cultural contexts. Addressing this gap, we analyzed and compared the adaptive thermal comfort responses in different naturally ventilated buildings located in temperate oceanic regions arising due to the high latitude in Europe and the elevated Himalayan region of Darjeeling, India. A mixed-methods approach was used with data from classrooms, offices, and residential buildings with adaptive thermal comfort modeling. The results show that European buildings exhibit narrower thermal comfort ranges compared to Darjeeling, for example, 21.2~24.8 °C versus 16.0~21.6 °C for 80% comfortability in classroom settings, respectively. Statistical analysis revealed significant differences in clothing insulation levels, with occupants in Darjeeling buildings demonstrating higher variability (mean rank 2103.31) compared to their European counterparts (mean rank 1207.30, p < 0.001). Additionally, a stronger correlation between indoor and outdoor air temperature was observed in Darjeeling (R: 0.785, p < 0.001), reflecting limited thermal buffering compared to European buildings (R: 0.372, p < 0.001). The paper advances adaptive thermal comfort models that account for regional differences and links these finding to sustainable building practices. The findings provide actionable insights for energy-efficient, climate-responsive building practices while supporting global sustainable development goals. Full article

The escalating environmental threat of indoor overheating, exacerbated by global climate change, urbanisation, and population growth, poses a severe risk to public health worldwide, specifically to those regions which are exposed to extreme heat events, such as Australia. This study delves into the critical issue of overheating within residential buildings, examining the existing state of knowledge on overheating criteria and reviewing overheating guidelines embedded in (a) international standards and (b) national building codes. Each regulatory document is analysed based on its underlying thermal comfort model, metric, and indices. The advantages and limitations of each document are practically discussed and for each legislative document and standard, and the quantitative measures have been reviewed, analysed, and summarised. The findings illuminate a global reliance on simplistic indices, such as indoor air temperature and operative temperature, in the existing regulatory documents. However, other critical environmental parameters, such as relative humidity, indoor air velocity, and physiological parameters including metabolic heat production and clothing insulation, are often not included. The absence of mandatory regulations for overheating criteria in residential buildings in some countries, such as in Australian homes, prompts the call for a holistic approach based on a thermal index inclusive of relevant environmental and physiological parameters to quantify heat stress exposure based on human thermal regulation. Gaps and limitations within existing guidelines are identified, and recommendations are proposed to strengthen the regulatory framework for overheating risk assessment in residential buildings. The findings hold significance for policymakers, building energy assessors, architects, and public health professionals, providing direction for the improvement of existing, and development of new, guidelines that aim to enhance indoor thermal condition and population health while ensuring energy efficiency and sustainability in the building stock. Full article

Current thermal comfort constructs are perceptional, and their relationships to the physiological responses are not fully understood. The latter are very important, not only to indicate personal comfort perception but also to protect personal health against cold and heat stresses. This paper combined a two-node bioheat model with the metabolic-based predicted mean vote index (MPMV) to uncover the relationships between the physiological responses and perceptional thermal sensation at steady-state conditions. The MPMV index accounts for sweating and non-shivering thermogenesis (NST) at the neutral comfort state and handles both core and skin cooling cases. Simulations were conducted for adults in typical indoor environment conditions. The physiological responses investigated included the body, core and mean skin temperatures, skin evaporative heat flux, shivering metabolic rate, and skin blood flow. The study revealed that only the mean skin temperature and skin blood flow can discriminate between comfort perception levels and can therefore be used alone or combined with other variables as alternative physiological indicators. The comfort range (MPMV within ±1) in terms of the mean skin temperature is maintained by regulatory sweating and/or NST and gets wider with increasing activity levels. The study also offered important insights for practical applications and future research. Full article

This study proposes an occupant-centric control strategy for residential heating systems, aiming to enhance thermal comfort and reduce energy consumption. A sensor station utilizing a frequency-modulated continuous wave radar sensor was developed to detect occupancy and infer activities within residential spaces. By analyzing field measurement data, schedules for occupancy and activities were established. These schedules were then used to implement a variable control strategy for the hydronic radiant heating system, adjusting its operating characteristics based on the identified activities. The proposed control strategy, which includes resetting the indoor set temperature during unoccupied periods and adjusting it during sleep to account for changes in metabolic rate and clothing insulation, resulted in significant energy savings. Compared to continuous operation, the hydronic radiant heating system’s energy consumption was reduced by approximately 21% on peak load days and up to 34% over three winter months. This study demonstrates the potential of occupant-centric control for achieving substantial energy savings in residential buildings while maintaining occupant thermal comfort. Full article