Thermal Comfort Characteristics Research Articles

Energy efficiency and thermal comfort characteristics of convection–radiation combined cooling system in office buildings

Energy efficiency and thermal comfort characteristics of convection–radiation combined cooling system in office buildings

Research on Automotive Seat Heating Strategy Based on Objective Thermal Comfort Evaluation

Abstract Seat heating is an essential means to improve cabin occupant thermal comfort. How to set a reasonable seat heating strategy is very important to improve occupant thermal comfort and reduce vehicle energy consumption. Based on objective thermal comfort evaluation criteria, this paper analyzes three strategies: fixed heating power, fixed seat surface temperature, and intermittent seat heating. It explores the occupant thermal comfort characteristics under different strategies. It is found that the optimum heating power or optimum seat surface temperature to maintain occupant thermal comfort varies with the initial seat temperature. Compared with the two strategies of fixed heating power and fixed seat surface temperature, the intermittent seat heating proposed in this paper can make the human body reach the optimal state of comfort in a shorter period, and the power consumption is less as the seat heating is opened for a longer time. This intermittent seat heating strategy not only adapts to different low-temperature environments outside but also provides sufficient safety guarantees while improving human thermal comfort. It can provide some references for the design of car seat heating and research on passenger cabin thermal comfort.

Thermal comfort characteristics of a catalytic combustion heater under wind-chilled exposure

Heating in wind-chilled environments is a serious task. The catalytic combustion heater (CCH) provides more efficient and cleaner in combustion compared to conventional heaters with high pollutant emission and low energy utilization. In this paper, the heating ability of CCH on human body in a wind-chilled environment (apparent temperatures between −14.8 °C and 12.4 °C) was investigated by collecting skin temperature and subjective thermal evaluation data from 23 subjects. The impact of cold air on localized heating of body parts by CCH was clarified using decision trees and dimensionless correlation coefficients. A human-computer interaction regulation strategy was proposed to simultaneously satisfy the requirements of effective heating, low energy consumption, and low pollution. Finally, CCH and a commercial heater were compared in terms of heating effectiveness and energy consumption in a real outdoor environment. The results showed that CCH effectively solved the problem of excessive cold extremities, and the temperature difference between thoracoabdominal area and extremities was reduced by 57.5–87.9% to within 2 °C. In a strong convective environment, wind speed was the decisive factor (coefficient of 0.95), inducing 46% radiant heat loss. Inputting personnel subjective perception, dynamic environmental parameters, and pollutant thresholds to adjust the injected gas flow enabled intelligent control. In a real cold scenario, the CCH saved 65.9% of energy compared to a commercial heater when achieving the same heating effect. This study provides a reference for the application of catalytic combustion technology in cold outdoor heating and also provides an important theoretical basis for the construction of heating strategies for CCH.

Seasonal characteristics of outdoor thermal comfort and residential electricity consumption: A Snapshot in Bangkok Metropolitan Area

Outdoor thermal comfort negatively influences urban residents’ health and increases residential electricity consumption (REC) for cooling demand. This study adopted the remote sensing-based modified temperature-humidity index (MTHI) to monitor and assess seasonal and spatial characteristics of urban thermal comfort and its association with REC. Thermal comfort and REC have a strong correlation (p < 0.05) and the same seasonal patterns as regional climate patterns. Thermal comfort is mainly controlled by land use, land cover (LULC), and physical characteristics of the built environments. Among the physical features, the building height is the most prominent element stimulating thermal discomfort as it regulates other elements linking to urban microclimates, such as sky view factor and ventilation. The thermal comfort in a particular region will be remarkably improved when urban density and building height remain under 65.43% and 17.88 meters, respectively. A green space proportion above 18.9% is also a reference value to optimize thermal comfort in built environments. The most vulnerable regions because of thermal discomfort in the Bangkok Metropolitan Area (BMA) account for 21.4% of the dense urban centers, with a building density of 72.5% and a population density of 17,173 persons/km2. The research findings enrich the current knowledge of thermal comfort characteristics and REC, which are significantly helpful for regional planning to mitigate thermal discomfort in this megacity.

Evaluation of the Moisture Management, Air and Water Vapour Permeabilities of Knitted Fabrics for Garments

The market today offers a variety of fabrics that may be utilised to create any style of clothing. Fabrics are periodically altered as a result of technology’s continual growth, to the point that it became difficult for clothes makers to assess the fabric characteristics related to thermal comfort. This paper reports some investigations on the moisture management and permeability properties of several commercial knitted fabrics intended for garment application. The fabric’s ability to manage moisture as well as its air and water vapour permeability were assessed. A fabric rating index was used to combine the results from each test to determine the fabric’s thermal comfort characteristics. Among the five knitted fabrics, the fabric comprised of nylon &amp; polyester with jersey structure gave the highest assessment rating which is 5. The study serves as a future reference for future textile and garment industry, that implement the laboratory method used in this paper i.e moisture management, water vapour and air permeability in choosing the better thermal comfort qualities for general wear.

Optimal Selection of Cotton Fabrics: A WASPAS Method Approach

Always used for cotton-rich materials. WASPAS Cotton Fabric Selection in this paper, “the WASPAS method, a relatively fresh and computationally powerful MCDM (Multi-Criteria Decision Making) tool”, is suggested to rank ten candidate cotton fabrics according to four cloth properties such as: “cover, thickness, area density, and permeability”. The suggested fabrics are evaluated and chosen in order to achieve the best thermal comfort characteristics. “Sample Number 3 ranks first (best option) with the highest evaluation score of 0.95281, while Sample Number 6 ranks tenth with the lowest evaluation score of 0.50685.” The proposed method's ranking results demonstrate a substantial agreement in ranking with previous approaches, as evidenced by the extremely high standard coefficients of correlation. With rank coefficients of correlation higher than 0.90, the ranking methods provided by the four hypothetical weight sets have the highest degree of agreement. Furthermore, even if the original making choices team is changed, that will be no rank reversal. As a result, sensitivity analyses based on altering criterion weights and the impact of dynamic matrices improve the proposed approach's stability and robustness in terms of ranking success.

Investigation on Thermal Comfort Characteristics of Newly Engineered Yarn Umorfil® Knitted Fabrics

This study investigated the thermal comfort properties of knitted fabrics produced from newly engineered Umorfil® yarns and their blends with Tencel®, wool, acrylic and polyester yarns. Single jersey-knitted fabrics were produced with 50/50% blended yarns (Umorfil®/Tencel®, Umorfil®/wool, Umorfil®/acrylic, and Umorfil®/polyester) and with 100% Umorfil® yarn for comparison. In this regard, the thermal comfort properties (thermal conductivity, thermal resistance, thermal absorptivity), air permeability, relative water vapour permeability, water absorbency, and wicking characteristics of these fabrics were measured and evaluated statistically. The results revealed that, 100% Umorfil® and 50/50% Umorfil®/Tencel® fabrics provided better characteristics in terms of thermal conductivity, air permeability, water absorbency, wicking behaviours, and colder feelings for the use of fabrics in hot climate products. It is also suggested that owing to the synergistic effect of these two materials, the blend of Umorfil® with Tencel® enhanced the thermal comfort and liquid moisture transmission capacities of the fabrics.

Indoor thermal comfort evaluation of traditional dwellings in cold region of China: A case study in Guangfu Ancient City

Global climate change has led to increased differences in the indoor thermal environment of traditional dwellings and residents' thermal adaptability, but quantitative research in this area needs to be updated and improved. In this paper, taking the old and new types of traditional dwellings of Guangfu Ancient City in Hebei province, China as the example, we first investigated the current situation of indoor thermal environment and thermal comfort characteristics of residents by means of subjective questionnaire survey and objective data measurement. The measured data showed that the average indoor temperature of old-type traditional dwellings in winter was far lower than the thermal comfort range of human body, and it was also higher than the relevant standard in summer. Secondly, we established a new thermal comfort evaluation model of traditional dwellings and proposed a new thermal neutral temperature of residents: old-type traditional dwellings (18.1 °C in winter and 27.1 °C in summer), new-type traditional dwellings (19.8 °C in winter and 25.7 °C in summer). Although the measured data showed that the thermal environment quality of the old-type traditional dwellings was poor, the residents had strong thermal adaptability. Finally, we put forward the different living performance improvement strategies of old and new types of traditional dwellings: The old-type traditional dwellings should focus on strengthening the thermal performance of the envelope structure, while the new-type traditional dwellings should solve the problem of low indoor humidity in winter. This research improves the evaluation system of human thermal comfort of dwellings in cold region of China, and provides a good case reference.

The effect of weft yarn type and elastomer yarn threading on the properties of elastic warp knitted fabrics. Part II: Thermal comfort properties

The aim of this study is to determine the performance properties of elastic warp-knitted fabrics used for medical purposes. The samples were knitted using different weft yarn material and changing the threading order of elastomer yarn. The detailed results of the dimensional and elasticity performance of elastic warp-knitted fabrics had been reported in Part I of this series. In this part, the effects of weft yarn material and the threading order of elastomer yarn on the thermal comfort characteristics were investigated. It has been seen that the type and linear density of the transverse weft yarns and the number of elastomer yarns in the fabric structure affected significantly the thermal comfort and permeability characteristics of the developed elastic warp-knitted fabrics. According to the results, using polyester yarns as weft and reducing the number of elastomer yarns led to an increase in air permeability. Additionally, the thermal conductivity characteristics of the fabrics increased as the number of elastomer yarns in the structure increased. It has been seen that from the results, the water vapour resistance coefficient of the samples is appropriate for the usage of these fabrics in medical products.

Iot application for energy poverty detection based on thermal comfort monitoring

The development of a datalogger for identifying Energy Poverty (EP) using thermal comfort monitoring is described in this work. There is not a uniform definition of EP, and no global recommendations indicating the thermal comfort characteristics that should be utilized to identify EP. Most Internet of Things (IoT)-based systems designed for EP identification measure energy consumptions (electricity and gas). There is a lack of works that use IoT-based systems to identify EP through the monitoring of thermal comfort parameters. To address the deficiencies discovered in the identification of EP from the perspective of thermal efficiency, an IoT-based monitoring system was designed, developed, and tested. A first pilot was installed in a household in Getafe. A full month of temperature, relative humidity, and CO2 concentration measurements were utilized to evaluate the system, which was then compared to a commercial system. The results revealed that the new IoT-based approach was very dependable and may be used to accurately monitor EP-related parameters.

In vitro experimental study on effect of fiber denier, yarn doubling, and specialty treatments on physical and thermal behaviors of knitted sports socks

Knitted sports socks remain in continuous scuff with wearers’ feet and shoes during activities. Such continuous physical contact governs severe pills on socks surface, which is unpleasant for both the wearer and the working life of socks. Hence it becomes necessary to take measures for controlling fabric deterioration, that is, anti-pilling treatments. Though pilling performance is enhanced; however, thermal comfort characteristics are compromised through the treatments. Simultaneous acquirement of both pilling and thermal characteristics is an area of interest. Fiber denier and yarn doubling techniques are among the influential factors in the solution to the problem. Specimens have been developed using four different fiber deniers, two yarn doubling conditions, and two specialty wet treatments under a full factorial experimental design. Results showed a significant variation in pilling behaviors and thermal characteristics before and after treatments in the statistical analysis, predicting the possible stages, that is, a combination of experimental factors for desired characteristics attainment.

여름철 계룡산국립공원 탐방로의 열쾌적성 및 어메니티 관리 연구

This study was conducted to understand the weather characteristics of the mountain environment and the thermal comfort of Gyeryongsan National Park trail and to provide information on activity time, activity space, and activity amount. For the analysis of the thermal comfort of the trail, the temperature of the city center in summer, the average temperature of the National Park Disaster Prevention Weather System (AWS), and the trail. Also, Microclimate elements and canopy closure were also measured in four major trails in Gyeryongsan National Park. After investigating a total of 240 points, thermal comfort was identified. When comparing the average temperature of the city center, National Park AWS, and trail, the average temperature was higher in the order of the city center, Gabsa AWS, Donghaksa AWS, Gabsa Trail, and Donghaksa Trail. As a result, it means that the thermal pleasure experienced by visitors should be considered. According to a survey of four major trails, the average canopy closure is Donghaksa~nammaetop route was high in the order of Donghaksa~Gwaneumbong route, Gabsa~Yeoncheonbong route and Gabsa~Geumjandigogae route. When PMV(Predicted Mean Vote) is 2.8MET, The PMV was highter in the order of Gabsa~Geumjandigogae route, Gabsa~ Yeoncheonbong route, Donghaksa~nammaetop route, Donghaksa~Gwaneumbong route. Through the survey, time information, spatial information, and activity information with high thermal comfort could be presented. By grasping the thermal comfort characteristics of the trail, we intend to lay the foundation for forest trail management measures that can increase the amenity of the trail.

Thermal comfort characteristics and heating demand of people with different activity status during extremely cold exposure

Extremely cold weather frequently occurs worldwide, increasing the risk of exposure to extremely cold environments, particularly for outdoor workers. Cold stress can significantly reduce work performance and impair workers’ health and safety. However, few studies have focused on the thermal comfort characteristics and heating demands of people involved in different activities during extremely cold exposure. Herein, 18 male subjects were recruited to perform different activities in a cryogenic chamber with an ambient temperature of −14.0 °C. They underwent 15 min of standing adaptation, 40 min of heating and 15 min of standing recovery. During the heating phase, they experienced four activity status with adjustable heated garments switched on: standing, continuous 4 km/h and 6 km/h walking, and intermittent 4 km/h walking. Variations in subjective perception, physiological responses and heating parameters over time were recorded throughout the experiments. The thermal sensation zone corresponding to thermal comfort shifted and expanded towards the warm side, which may be attributed to local cold exposure. Subjective feedback and self-adjustment were combined to quantify heating demands. Thermal comfort and energy savings were simultaneously considered when determining the heating demand. The comfortable temperature inside the clothes for standing was 23.5–32.9 °C, and active heating was not required for walking at 6 km/h. The actual heating demand decreased with increasing activity intensity and was much lower than the commercially heated garments provided. Heating strategies for different activity status were recommended to guide the design of personal comfort systems.

Adaptive thermal comfort model based on field studies in five climate zones across India

Indian residences are vulnerable to heat-driven discomfort amid the mounting prevalence of weather extremes, residential design and construction practices, and densifying urbanscapes. Therefore, it is vital to understand the thermal comfort characteristics of nationwide residences. This study proposes an adaptive thermal comfort model based on yearlong field surveys in eight cities located across five climate zones of India – the India Model for Adaptive Comfort - Residential (IMAC-R). The model prescribes the operative temperature bands for 80% and 90% thermal acceptability in correlation with the outdoor reference temperature, applicable to mixed-mode (MM) and naturally ventilated (NV) residences.More than 80% of the Indian residential occupants experienced a neutral thermal sensation in the indoor operative range of 16.3–35 °C in response to a 5.5–33 °C variation in the 30-day outdoor running mean temperature. Comparing the proposed model with the PMV model revealed that the latter underpredicts the thermal adaptivity of Indian occupants. The model was also compared against its predecessor – India Model for Adaptive Comfort for Commercial Buildings (IMAC MM and NV), along with relevant global and regional thermal comfort models. On average, the neutral temperature prescribed by IMAC-R was warmer than the temperatures prescribed by IMAC MM and NV by 2.9 °C and 2.1 °C, respectively; it was also warmer than the temperature prescribed by the recent ASHRAE-55 and EN 16798-1 models by 2 °C and 0.3 °C, respectively. IMAC-R reserves the prospect of addressing the thermal comfort needs of the national population while paving the way for long-term energy savings and climate action.

The Comfort Map—A Possible Tool for Increasing Personal Comfort in Office Workplaces

Previous studies have shown that indoor environmental quality (IEQ) parameters may have a considerable effect on office employees’ comfort, health and performance. Therefore, we initiated a research program to help occupants identify IEQ parameters they perceive as risk factors for their health in an office and enhance their comfort levels in an office environment. Since we assumed that office employees might have different indoor environmental quality expectations related to their work area and that these differences could be measured, our objective was to develop an office ‘comfort map’ based on occupants’ individual IEQ preferences. Thus, the goal of the comfort map would be to help tailor office spaces to their occupants’ health and comfort expectations. The comfort survey was developed to assess the comfort-related opinions of the occupants, based on IEQ parameters (visual comfort, acoustic comfort, air quality and thermal comfort) of a chosen open-plan office building. The survey also assessed the degree to which the given IEQ parameter was considered a health risk factor by occupants or caused a negative comfort sensation for them. The survey was filled in by 216 occupants. The answers were then analyzed with the help of a frequency table depicting relative frequency. The measurements of IEQ parameters took place in an open-plan office in the chosen office building (a Hungarian subsidiary’s office building belonging to an international company in Budapest). The occupants had different opinions regarding the perceived effects of the IEQ parameters on their health and comfort. Almost two-thirds of the respondents (64.8%) were dissatisfied with the adjustability of the noises and sounds IEQ parameter at their workstation. Furthermore, half of the respondents (50.1%) were dissatisfied with the adjustability of ventilation. Most of the occupants (45.8%) considered noises and sounds as the IEQ parameter that had a negative effect on their health. There were also IEQ differences between different areas of the office space. Based on these results, a comfort map was developed for the office. The comfort map contains information about the IEQ characteristics of each workstation by depicting the thermal comfort, carbon dioxide, visual comfort and acoustic comfort characteristics of a given workstation on a relative scale. Based on the thermal, air, acoustic, and lighting differences between the workstations, occupants can select their preferred workstations when a desk-sharing system works. Although still in its pilot phase, the comfort map could increase the chances for office employees to find the workstation best suited to their IEQ expectations. This could improve occupants’ overall comfort level, which could in turn enhance occupants’ productivity and mental as well as physical health.

Climatic zoning for the building thermal design in China's rural areas

Building climatic zoning is a prerequisite for implementing building energy efficiency technology, which can help code makers and architects have an accurate understanding of the local climatic conditions. It takes the extreme monthly average temperature as the zoning index in the existing climatic zoning of rural areas in China. There will be unreasonable design phenomena of insufficient or excessive thermal insulation for a building envelope in rural areas. Aiming at the above problems, this paper modifies the current zoning. This research established the cooling and heating degree-day indexes HDD14 and CDD30 based on the thermal comfort characteristics of rural occupants and used the threshold method to subdivide rural areas into eight sub-zones. The results show that the problem of insufficient or excessive thermal insulation in rural areas can be effectively solved by replacing the extreme monthly average temperature index with the degree day index and the annual cumulative building load can be reduced by 6.4% on average without increasing the insulation cost. After more detailed zoning, the variance within the group is reduced and it accurately describes climate diversity, which is conducive to implementing climate-responsive energy-saving design in each subzone. Practical application: The major purpose of this paper is to solve the problem of unreasonable climate zone boundaries specified in the existing Design Standard for Energy Efficiency of Rural Residential Buildings. The existing zoning has led to conflicts between the actual heating demand and the building envelope thermal parameter limits specified in the standard. This work redefines the boundaries of the existing map using more up-to-date weather data to provide the right guidance for architectural designers.

Effects of hip protective clothing on thermal wear comfort of clothing ensembles

PurposeThis paper aims to examine the influence of hip protective clothing on ensemble performance attributes related to thermal comfort. It also explores the effect on protective pads of various materials and the arrangements of material. The thermal comfort characteristics are thermal insulation and moisture vapour resistance.Design/methodology/approachFor this research, four ensembles of clothing were used: one ensemble without hip protective clothing and three ensembles with hip protective clothing. A thermal manikin was used to test the thermal insulation and moisture vapour resistance of the ensembles.FindingsThe findings revealed that incorporating hip protective clothing into the clothing ensembles influenced the thermal resistance and moisture vapour resistance of the ensemble. In the “all zones group,” the influence of the hip protective clothing depended on clothing style, with hipster-style clothing producing insignificant changes. In the “hip zones group” and “stomach and hip zones group,” hip protective clothing strongly influenced the thermal comfort attributes of ensembles. Pad material and volume play important roles in these changes in thermal comfort attributes.Originality/valueThese outcomes are useful for the design and engineering of hip protective clothing, where maximizing protection while minimizing thermal and moisture vapour resistance is critical for wear comfort and adherence in warm or hot conditions. The designer should consider that material, volume and thickness of protective pad affect the overall thermal comfort attributes of the hip protective clothing.

Thermal comfort analysis of radiant cooling panels with dedicated fresh-air system

Radiant system has been increasingly applied in buildings due to its good thermal comfort and energy-saving potential. In this research, a simplified predicted mean vote (PMV) model and sensible cooling load equation were proposed based on human thermal comfort. Simulations were carried out using Airpak to explore relationships among thermal comfort characteristics, design and operation parameters. Results show that radiant surface temperature, fresh-air supply temperature and the area ratio are correlated approximately linearly with the indoor air temperature, while the relative humidity has little effect on the indoor air temperature. The indoor air velocity in the simulated environment was no more than 0.15 m/s, satisfying the requirements of limit values in the occupied zone. The results indicate that the optimum radiant surface temperature ( tc) is 19°C to 23°C when fresh-air supply temperature ( ts) is 26°C. The relative humidity ( φ) should be maintained at 50% to 70%, and the area ratio of radiant panels to total surfaces ( k1) should be kept within 0.15 to 0.38 when the radiant surface temperature is 20°C and the fresh-air supply temperature is 26°C. The simplified PMV model and the sensible load equation can provide reference for panel design based on characteristics of radiant cooling panels with a dedicated fresh-air system.

Energy saving potentials of integrating personal thermal comfort models for control of building systems: Comprehensive quantification through combinatorial consideration of influential parameters

Research studies provided evidence on the energy efficiency of integrating personal thermal comfort profiles into the control loop of Heating, Ventilation, and Air-Conditioning (HVAC) systems (i.e., comfort-driven control). However, some conflicting cases with increased energy consumption were also reported. Addressing the limited and focused nature of those demonstrations, in this study, we have presented a comprehensive assessment of the energy efficiency implications of comfort-driven control to (i) understand the impact of a wide range of contextual factors and their combinatorial effect and (ii) identify the operational conditions that benefit from personal comfort integration. In doing so, we have proposed an agent-based modeling framework, coupled with EnergyPlus simulations. We considered five potentially influential parameters and their combinatorial arrangements including occupants’ thermal comfort characteristics, diverse multi-occupancy scenarios, number of occupants in thermal zones, control strategies, and climate. We identified the most influencing factor to be the variations across occupants’ thermal comfort characteristics - reflected in probabilistic models of personal thermal comfort - followed by the number of occupants that share a thermal zone, and the control strategy in driving the collective setpoint in a zone. In thermal zones, shared by fewer than six occupants, we observed potentials for average energy efficiency gain in a range between −3.5% and 21.4% from comfort-driven control. Accounting for a wide range of personal comfort profiles and number of occupants, the average (±standard deviation) energy savings for a single zone and multiple zones were in ranges of [−3.7 ± 4.8%, 5.3 ± 5.6%] and [−3.1 ± 4.9%, 9.1 ± 5.1%], respectively. Across all multi-occupancy scenarios, a range between 0.0% and 96.0% of combinations resulted in energy savings.

Effect of Blend Ratio on the Thermal Comfort Characteristics of Cotton/Bamboo Blended Fabrics

ABSTRACT The present work explains the thermal comfort properties of cotton (100:0), bamboo (0:100), and cotton:bamboo (70:30, 50:50, 30:70) blended yarns/fabrics. The physical characteristics of cotton:bamboo (50:50) blended fabrics show the very closest properties of pure cotton yarn fabrics for the count of 30 tex. The proportion of bamboo fiber in the fabrics influenced the physical properties of the yarn such as areal density, fiber fineness, and other structural parameters. The plain-woven fabric generally aligned as 30 tex in warp direction for pure cotton yarn and 30 tex in weft direction for pure bamboo yarn. Similarly, the experiment is conducted for various proportions and noted that cotton in warp and bamboo in weft direction depicts higher air permeability and water vapor permeability (WVP) compared to all the other fabrics. From the comfort properties of fabrics, the thermal conductivity and the thermal resistance of the blended fabrics were found to be decreased with a gradual increase in the ratio of bamboo fiber. The reduction in inter-yarn space and higher yarn hairiness leads to reduction in air and water permeability values with an increase in cotton proportion. The enhanced WVP and air permeability of the prepared fabrics were observed with an increase in bamboo content.