Thermal Comfort Sensation Research Articles

Evaluating a novel portable semiconductor liquid cooling garment for reducing heat stress of healthcare workers in a hot-humid environment

Limited research focused on exploring personal cooling garments (PCGs) that offer excellent portability, along with a substantial, long-lasting, and consistent cooling effect for healthcare workers exposed to extreme heat while combating the COVID-19 pandemic. To address this gap, a novel, energy-efficient, and portable semiconductor liquid cooling garment (SLCG) was introduced, which incorporates a semiconductor-powered cold source and a cooling vest crafted from a semi-transparent thermoplastic polyurethane (TPU) film that offers extensive body coverage. Its practical cooling efficacy was assessed through a human trial involving ten male participants engaging in two protocols under a hot-humid environment (i.e., 30 ± 0.5 °C, RH = 80 ± 5 %). These protocols included both low-intensity (Prot.1) and moderate-intensity (Prot.2) exercises, mimicking the physical demands faced by healthcare workers. SLCG significantly reduced the mean, torso and local skin temperatures during both Prot.1 and Prot.2 (p < 0.05), also with a notable reduction in heart rate and sweat loss during Prot.1 (p < 0.05). Rating of perceived exertion as well as thermal sensations, wetness sensations and comfort sensations in the whole-body and local-body (i.e., head & neck, trunk, arms and legs) were all remarkably improved using SLCG during Prot.1 (p < 0.05). These perceptual sensations in SLCG were only improved in the whole body during the resting stage, and in the trunk region during Prot.2 (p < 0.05). Furthermore, participants felt no significant added weight or movement restrictions with SLCG in either protocol.

Thermal comfort in open spaces in the arid climate of Kuwait: a study of construction training institute students

This article assesses the students’ sensation of thermal comfort in the open areas of the construction training institute in Kuwait, a hyper arid desert. This is carried out using field measurements from the site, and then handing out in-depth questionnaires to 100 students. The questionnaire provides great insight into the students’ perception of thermal comfort, as well as the constituents that impact it. Moreover, the students’ recommendations to improve thermal comfort in open spaces sheds light on the various methods that should be further researched and quantified. These solutions include adding substantial vegetation and trees for shading and redesigning the inadequate existing shading devices on campus. Overall, the findings indicate that the air temperature and humidity are well below the comfort level. These field measurements are sufficiently validated with the questionnaire results that indicate a substantially negative experience. While outdoor thermal comfort is heavily under researched in Kuwait, there are endless opportunitiesfor improvement and development. Consequently, this paper acts as a catalyst for future endeavors, quantitative analysis, and raised awareness

Field Investigation on Adaptive Thermal Comfort in Rural Dwellings: A Case Study in Linyi (China) during Summer

A large number of people in China still live in rural villages. The indoor environment of these rural dwellings directly affects the quality of life of the occupants. Nevertheless, constrained by the quality of dwelling construction, rural buildings have poorer indoor environments and, at the same time, have a higher operating energy consumption. However, inadequate attention has been given to the summer thermal environment in cold regions. This work has been carried out around the thermal environment of rural residences in cold regions during summer. Field measurements, questionnaires, and data analysis were used in this study. We recorded the indoor and outdoor thermal environment parameters on a typical summer day in the Linyi rural area. Moreover, the subjective sensations and thermal adaptive behaviors of the participants were recorded in detail with a questionnaire. Linear regression showed that the neutral temperature for residents in summer was 27.52 °C, with acceptable temperatures ranging from 25.14 °C to 29.9 °C. Age and gender differences were found to affect the occupants’ sensation of thermal comfort and humidity, as well as their thermal adaptive behavior. In addition, a thermal adaptive model has been constructed in the study, which will further enrich the thermal adaptive investigation and provide a scientifically sound reference for the renovation and development of the local rural areas.

On the effectiveness of Reynolds-averaged and subgrid scale models in predicting flows inside car cabins

The aim of the present study is to analyze the performances of unsteady Reynolds-averaged Navier–Stokes (URANS) and large eddy simulation (LES) approaches in predicting the airflow patterns inside car cabins and to give insight in the design of computational fluid dynamics simulations of a real car cabin. For this purpose, one eddy viscosity-based turbulence model (shear stress transport k–ω) and two subgrid scale models (wall-adapting local eddy-viscosity and dynamic kinetic energy) were tested, and numerical results were compared with particle image velocimetry measurements carried out on a commercial car. The URANS model exhibited great accuracy in predicting the mean flow behavior and was appreciably outperformed by the LES models only far from the inlet sections. For this reason, it was deemed suitable for conducting further analyses, aimed at characterizing the airflow patterns in winter and summer conditions and performing a thermal comfort analysis. The thermal regime was found to have a very little effect on the air flow patterns, once the quasi-steady state regime is achieved; in fact, both in winter and in summer, the temperature field is fairly uniform within the car cabin, making the contribution of buoyancy negligible and velocity fields to be very similar in the two seasons. Findings also reveal that thermal comfort sensation can be different for passengers sharing the same car but sitting on different seats; this aspect should be considered when designing and operating the ventilation system, since the minimum comfort requirements should be met for all the occupants.

The Effect of Length of Service in a Thermal Environment on Thermal Comfort and Mental Stress

An inappropriate thermal environment negatively impacts workers, causing mental stress and safety accidents. Unskilled workers are more vulnerable to industrial accidents and thermal stress compared with skilled workers due to suboptimal and unfamiliar work. Previous studies have focused on individual characteristics (such as gender, age, and race), with limited emphasis on the thermal comfort sensation. This study identified the preferred thermal environment according to work experience and how mental stress differed between unskilled and skilled workers by examining their thermal comfort sensation. Predicted mean vote (PMV) was used as an indicator of the thermal environment, and five environments were constructed for PMV: −2, −1, 0, 1, and 2. Participants were recruited among current workers and the public. Mental stress and thermal comfort sensation were assessed using heart rate variability and thermal comfort vote, respectively. This study demonstrated that the skilled group experienced higher mental stress and a lower thermal comfort sensation. Contrastingly, in the sensitivity analysis, the unskilled group exhibited greater sensitivity to changes in the thermal environment. Through a comprehensive analysis, this study derived an optimal PMV range for each group. The findings can provide a reference for configuring the optimal thermal environment of the workplace.

Effect of heat mitigation strategies on the thermal environment of hardened pavement and pedestrian thermal comfort in a hot and humid area: A case study of Guangzhou, China.

The synergistic effect of heat waves and urban heat islands (UHI) adversely affect the urban environment, building energy consumption, and human health. The absorption and storage of short-wave radiation by hardened pavement is the primary reason for high-temperature heat waves and the UHI effect. Three mitigation strategies were assessed to alleviate the influence of high-temperature hardened pavement on the thermal environment and thermal comfort of pedestrians, water-spray vehicles (spray) and pavement watering (watering) to take advantage of evaporative cooling, and a fan based on convective heat transfer. In addition, the fan-spray and fan-watering combinations were evaluated to increase the evaporative cooling rate. Field measurements showed that the five heat mitigation strategies improved the thermal environment and reduced environmental thermal stress. The thermal sensation, comfort sensation, and mean skin temperature (MST) were analyzed in thermal perception experiments. The result indicated that the mitigation strategies changed the subjects' thermal perception. Moreover, regression analysis between the universal thermal climate index (UTCI) and the thermal response showed that the neutral temperature and the range of comfort threshold of UTCI and MST increased after implementing the mitigation strategies.

Investigating the effectiveness of the Building’s envelope materials in hot and arid climates to achieve indoor thermal comfort

Envelope Building materials play an important role in architecture by providing protectionnecessities, comfort, and technical performance while promoting an architectural language and an image.The building envelope represents all the surfaces of a space, which consist of opaque parts such as walls,floors and roofs and transparent parts such as windows and openings. The building envelope is thepartition between the external and internal environment of the building which influences the heat transferbetween the two environments so it has a direct impact on the thermal comfort sensation which alsoinfluences the energy consumptions. This research focuses on the opaque building materials of theenvelope and their contribution in the thermal comfort and the energy consumption; an investigation ofthe impact and the thermal behavior of different envelope configuration materials under the climaticconditions of Biskra was carried, Algeria a hot and arid climate. The thermal performance of differentmaterials was compared using in situ measurement using “Testo 480” a hygrothermal scale and byanalyzing the results of a different simulation using “DesignBuilder v5.5” to perform a thermal andenergy analysis. The results show that choosing a multilayered isolated envelope such as double red brickisolated wall will likely affect positively the level of the indoor thermal comfort.

SENSATION ON FEET COOLING WITH THERMAL COMFORT IN A PORUS WALLED ROOM

Comfort for users is the goal of a arsitectural design. This study aims to propose a new innovations in the meeting room consept design with cases in the Faculty of Engineering meeting room, Udayana University in Jimbaran – Bali. Innovation which provides a sensation of thermal comfort, through the position of the wind speed/air movement. This meeting room is made porous on the underside of the wall. The study was conducted using the Ecotect-Winair(cfd) software to evaluate wind speed/air movement in the meeting room. Then use the CBE Thermal Comfort Tool to reveal the sensation that occurs. The direction of the wind that changes periodically and the sensation of thermal comfort based on different regions/tribes or individuals provide the limitations of this research. Thermal comfort as a bioclimatic approach in the context of green buildings. Green building design is a popular design today as a form of responsibility to the world. A novelty was found in the form of a cooling bioclimatic sensation by the wind speed on the feet which is felt on the skin around the footbridge with a new design concept in the meeting room.

Adaptive thermal comfort of residential buildings in the composite climatic region of India: a field study

ABSTRACT This paper presents the results of an adaptive thermal comfort field study conducted in the naturally ventilated residential buildings in the composite climate type of India over three main seasons i.e. monsoon, winter, and summer using ASHRAE’s class II field measurements protocols. 768 measurements were collated wherein subjective thermal comfort sensation, preference, and acceptance for indoor environment variables were thoroughly explored along with the adaptive actions of the users for four different times during a day. Correlation analysis helped decipher the relationship between subjective votes and thermal comfort evaluation parameters. Thermal environment acceptance during monsoon season and morning time was highest however the same was found lower during summers and afternoons. The middle age group had the lowest acceptance and well-acclimatized non-native participants had a good thermal acceptance. Education also affects thermal acceptance and it decreases with increasing education level. The comfort temperature and adaptive comfort equation were also studied and results were compared with national and international thermal comfort standards. This study predicted a wider thermal comfort range of 12.23–34.45°C and indicated revising TSI, the first thermal comfort index for Indian Subjects.

Improving Electric Vehicle Range and Thermal Comfort through an Innovative Seat Heating System

In the last decade, car manufactures invested a lot of effort to align their products to the latest energy directives which encourage the production and usage of electrified vehicles to reduce the greenhouse gases production. This resulted in several important developments, which enhanced the advantages of electric vehicles in terms of local emissions (zero tailpipe emissions), efficiency, convenience in urban areas and others and ultimately led to their ever-increasing adoption. However, there are still some challenges that need to be addressed. One example is the negative influence of low (winter) and high (summer) atmospheric temperatures on electric vehicle range due to the cabin temperature heating and cooling. This requires more efficient ways of using energy to avoid sacrificing the passenger thermal comfort for an increased vehicle range. The present study proposes a new strategy for heating the seats in electrically powered vehicles using an uneven distribution of the heating elements. The uneven positioning of the heating elements is based on the thermal sensitivity of the human skin measured data and scientific literature. For this, a thermal sensitivity test device was developed to map the human skin thermal sensitivity. To test the new solution, a vehicle seat was equipped with heating pads (arranged according to the position of the relevant human skin thermal sensitivity points). For the next step, comparative measurements (power consumption, temperature distribution—with an IR camera—and human subjectivity test) were carried out between a classical vehicle seat heating system and the newly proposed heating solution. The outcome of the study revealed that the proposed heating system will supply at least the same thermal comfort sensation as the standard vehicle seat but using only half of the energy consumption, which translates in an increase of the electrically powered vehicle range between 1.2% and 1.5%, depending on the climate and driving conditions (over the WLTC). For example, a vehicle with a 16 kWh battery driving over the WLTC in Frankfurt climate conditions can gain in 1 year between 139.6 and 164.5 km.

The adoption of pressure independent control valves (PICVs) for the simultaneous optimization of energy consumption and comfort in buildings

The optimization of energy consumption in buildings’ HVAC systems plays a crucial role in reducing greenhouse gas emissions worldwide. In new and deeply-renovated buildings, characterized by modulating terminal units and aiming at the maximum exploitation of renewables, an accurate hydraulic balance of the distribution network may become critical, resulting in a significant increase of pumping energy consumptions and a deterioration of indoor thermal comfort conditions. In the present paper, we compare the performance of traditional manual balancing valves and new pressure independent control valves (PICVs), used to balance the hydronic loop of HVAC systems. To perform this analysis, a new MATLAB-Simulink model has been specifically developed to simulate the behavior of PICVs and has been used in an application case study. The efficiency of manual and pressure independent control valves is evaluated numerically by simulating a multi-zone distribution network under variable operating conditions and considering different control strategies of the circulating pump. Results show that in off-design conditions, when some of the branches of the hydraulic network are closed, traditional manual balancing valves are not able to guarantee the nominal mass flow rate in the remaining loops. On the contrary, no significant variations of water mass flow rate are observed when PICVs are adopted, even in partial load conditions. Despite their additional cost, PICVs allow to ensure better indoor thermal comfort sensations for individuals, avoiding under/over-heating of rooms and, moreover, yield a decrease of the pump electric consumption with respect to traditional manual balancing valves. In addition, based on the obtained results, general rules concerning the adoption of PICVs are provided, depending on the extension of the hydraulic loop and the adopted pump control logic. The reported results highlight the role that PICVs can play to ensure energy savings in HVAC systems without penalizing users’ indoor comfort conditions.

A thermal comfort evaluation on vehicular environments based on local human body thermal sensations

With the rapid development of the automobile industry and increasing demand for automobiles, consumers also have more and more car requirements. They do not only consider energy, safety and price but also expect a good indoor environment and improved thermal comfort. In order to construct and apply a thermal comfort evaluation method suitable for Chinese consumers, a relationship between the equivalent space temperature and the thermal sensation was obtained by collecting characteristic thermal sensation data of the human body in different environments. An evaluation method based on whole-body and local thermal comfort sensation characteristics for adult Chinese males and females was designed, At the same time, the study found that women's tolerance for thermal sensation is lower and the thermal comfort zone is relatively smaller. In order to explore the accuracy of the evaluation method and a typical non-uniform vehicular environment was selected to verify the findings. The local and whole-body equivalent space temperature of the co-driver seat in the vehicle was tested with a warm dummy, through which whole-body and local thermal sensation values were predicted. The local and whole-body thermal sensation was tested with subjects' subjective experience under the same conditions. The predicted thermal sensation obtained through the equivalent space temperature was compared to the subjective experience results, and the correlation reached up to 0.911, while significance (two-tailed) only reached 0.002, it was possible to predict the thermal sensation vote within an accuracy level of 0.3 point, further proving the accuracy of the whole-body and local thermal comfort evaluation method for adult Chinese male thermal sensation characteristics as proposed in this paper. The results obtained in this study can be used to predict environmental thermal comfort.

The Impact of the Urban Heat Island on the Sensation of Thermal Comfort and Electricity Consumption in Sfax in Central-Eastern Tunisia during the Hot Season

This study follows on from the work on the urban climate of Sfax and its energy repercussions. The spatial configuration of the urban heat island (UHI) and the spatial distribution of the thermal comfort indices, the heat index (HI), the universal thermal climate index (UTCI) and the temperature humidity wind index (THW), resulting from the car survey method, essentially show the impact of land use and the distance from the coastline on the spatial distribution of air temperatures. A maximum difference of 7 °C between the city centre and the countryside is measured in very hot summer weather. During the night phase, the apparent temperatures are oppressive, particularly in the city centre, where HI and THW comfort indices exceeding 40 °C were calculated. Compared to the HI and UTCI, the THW demonstrates a much stronger variation due to the influence of wind between open areas and the downtown area. The intensity of thermal discomfort decreases as one moves towards the rural area (−15 °C compared to the centre), hence the impact on the consumption of electrical energy dedicated to air conditioning. The central part is the most energy-intensive area compared to the peripheral areas, especially during hot days when the use of air conditioners becomes constant, day and night.

The effectiveness of e-textiles in providing thermal comfort: A systematic review and meta-analysis

Thermal electronic textiles (e-textiles) are increasingly common in the market and aim to provide thermal comfort in cold environments. Currently, however, there is a paucity of information on the relative effectiveness of the different types of thermal e-textile. This study sets out to compare the effectiveness of a range of such textiles reported in the relevant literature. The study addresses the issue of heating effectiveness in terms of gender and particular body regions. Among the results reported, three primary categories emerged for investigation: (a) metabolic response, comprising metabolic rate and heart rate; (b) respiratory response i.e. mean skin temperature; and (c) perceptual response, including thermal sensation and comfort sensation. Eight eligible studies with a total of 83 subjects aged 23.4 ± 1.49 years, 40.96% male and 37.35% female and 21.69% in which gender was not reported, were investigated for the meta-analysis. Results show a significant improvement in changes in mean skin temperature and thermal sensation between the control and experimental groups via heating intervention ( p &lt; 0.05), but results were not significant for changes in metabolic rate, heart rate, and comfort sensation ( p &gt; 0.05). Regarding gender, thermal e-textiles significantly enhanced the changes in mean skin temperature in males and thermal sensation in both males and females ( p &lt; 0.05). With regard to different body regions being heated, there were significant effects on changes in mean skin temperature, thermal sensation, and comfort sensation in heating the upper torso ( p &lt; 0.05) and on changes in thermal sensation in heating the feet and toes ( p &lt; 0.05). The results reported here may serve as reference points for the further development of smart heating textile technology.

Trombe walls with porous medium insertion and their influence on thermal comfort in flats in Cusco, Peru

The Trombe wall is a passive indirect heating system which should be used in Cusco, Peru to improve thermal conditions against the typical frosts and low temperatures during winter in the high Andean regions. Due to this problem, the use of a modified Trombe wall with insertion of porous medium is proposed to improve thermal comfort in flat buildings in Cusco. This research aims to analyse and compare the performance of dwellings without Trombe wall, with traditional Trombe wall, and with Trombe wall with glass and plastic pellets insertion in thermal comfort improvement. Autodesk® CFD was used to simulate and analyse the system. The simulation was performed with three prototype flats (55 m2, 75 m2 and 95 m2) for six months of the year. From the results obtained, the level of thermal comfort in the traditional scenarios is low with an average PMV of -1.86, in the scenarios with Trombe wall is good and in the scenarios with Trombe wall with insertion of porous medium is slightly better than the previous one, reaching an average PMV of +0.10 and a temperature of 21.90°C. The study carried out is important because it represents an efficient eco-sustainable heating alternative that improves the thermal comfort sensation in houses during the coldest months of the year.

The Thermal Comfort Problem in Public Space during the Climate Change Era Based on the Case Study of Selected Area in Lublin City in Poland

Noticeable climate change in recent years is reducing the comfort of public spaces in the urban environment, and is becoming an element of urban policies. The adaptation to climate change requires the development of new design guidelines for the development of public spaces. The appropriate definition of development density, choice of building materials, technologies, planting species, and the used directions is a challenge that depends on local conditions. A representative public space located in the area of a multi-family housing estate built in the second half of the 20th century in Lublin (Poland) was selected for the study. The space has undergone redevelopment twice in the last 10 years. The aim of the study was to determine to what extent the executed and designed changes actually improve the thermal comfort of users. Quantitative and qualitative indicators of the successive phases of the investment were analyzed in the context of projected climate change. The simulation was developed using the ENVI-met version 5.0 software. As a result of the changes made, there has been an improvement in usability and comfort. Five simulations were carried out for the warmest day of the year for one of the public spaces in the city of Lublin. The sensation of PET thermal comfort was investigated for people aged 35 and 75, as a particularly sensitive group. The obtained result proved that the elderly feel higher temperature rates than younger people. In one of the simulations, new plantings were proposed to improve the local microclimate. The material temperatures of paved surfaces were also investigated. The article shows how the local microclimate and people’s desire to stay in a given space can be improved with new tree planting.

Post-Occupancy Evaluation of Thermal Comfort Sensation of Pupils in School Establishments under Hot Arid Climate Conditions

School establishments have been considered the foundation of various civilizations, due to the importance of the educational process in producing future generations and shaping healthy societies. This paper aims to evaluate the thermal comfort sensation of pupils in school buildings under hostile climatic conditions in hot arid regions. The study employed the use of the post-occupancy approach with subjective assessments through questionnaires and physical measurements of the environmental physical parameters of thermal comfort: temperature, relative humidity, and air velocity as objective assessments. These measurements were in parallel with survey questionnaires that were undertaken during regular class sessions covering the hot and cold conditions of a school year, polling responses from 281 participants on their perception of the indoor climate. Finger's comfort indicators are calculated (PMV, predicted mean vote; and PPD, predicted percentage of dissatisfied people); and the actual people's clothing and metabolic rate are estimated in order to conclude the prevailing indoor thermal conditions. The investigations were carried out on three samples of school buildings in Biskra (Algeria) of different architectural styles. The study’s results revealed that the levels of temperature were the most crucial parameter that influenced the thermal sensation with an average of 35C° with a PMV of 2.48, and 15C° in winter with a PMV of -2.56, indicating more than 90% dissatisfaction. Therefore, a well-thought bioclimatic school design is needed to ensure acceptable indoors, and promote healthy and safe learning spaces, by adopting sustainable design principles and low-energy-consuming techniques.

Study on thermal comfort of low-sweat and high-sweat young men based on heart rate variability analysis under different clothing

Thermal comfort is one of the most important factors affecting human performance. In recent years, the Low Frequency to High Frequency Ratio (LF/HF) index, which is obtained from the frequency analysis of heart rate variability, has been proposed as an accurate method for evaluating thermal comfort in different conditions. In this study, using LF/HF, the effect of sweating amount on thermal comfort under the influence of clothing characteristics was investigated. After a moderately heavy physical activity in the indoor situation and without good ventilation, skin temperature, electrocardiogram signal and a qualitative assessment of their thermal comfort were recorded in participants divided into two groups: low sweat and high sweat. The results of qualitative measurement and frequency analysis of thermal comfort were then discovered to have a significant correlation. According to findings, the low sweat group had less thermal comfort than the high sweat group ( p &lt; 0.05). The type of clothing was also found to have a significant effect on the thermal comfort sensation. Although the amount of sweating is an inherent feature of an individual, the feeling of thermal comfort can be improved ( p &lt; 0.05) by optimizing clothing characteristics for each group without spending more energy on cooling.

Analyzing Thermal Comfort Sensations in Semi-Outdoor Space on a University Campus: On-Site Measurements in Tehran’s Hot and Cold Seasons

Outdoor and semi-outdoor thermal comfort on the university campus is essential for encouraging students’ outdoor activities and interactions and reducing energy consumption in occupied buildings. For this reason, the current study presents on-site measurements and questionnaire surveys on a university campus in Tehran, Iran. It aims to investigate the most applicable thermal indices in Tehran’s cold and hot seasons. Measurements were conducted over winter and summer days; in addition, the survey collected 384 responses. The results confirm that the Predicted Mean Vote (PMV) and Physiological Equivalent Temperature (PET) indices are better predictors of semi-outdoor thermal comfort in summer and winter than Universal Thermal Climate Index (UTCI) and New Standard Effective Temperature (SET*), respectively, highlighting the importance of considering accurate thermal indices in different seasons. Finally, all analyses were gathered in a predictive empirical model, knowledge of which may be helpful in the planning and design of outdoor and semi-outdoor environments in Tehran and similar climates.

Experimental assessment of thermal comfort and indoor air quality in worship places: The influence of occupancy level and period

Worship places represent a unique type of buildings due to their functionality, dense occupancy, intermittent use, roof geometry, large inner space, and consumed energy of cooling/heating systems. In addition, thermal comfort and indoor air quality are decisive keys that affect the psychological and physiological conditions of occupants as well as their activity level and working efficiency. Though, a scarce number of studies focused on investigating the indoor conditions of worship places. Thus, a mosque located in Bahrain was selected to examine the influence of the occupancy level and period on thermal comfort sensation and indoor air quality. The readings of air temperature, humidity, air velocity, and CO2 concentration were recorded during real several occupancy levels and periods during the summer season. The measured findings of PMV and PPD metrics indicated that the social distancing between worshippers, during the SARS-CoV-2 pandemic, causes a feeling of coolness under the existing cooling system. Meanwhile, the 2-h occupancy period produced a 75% increment of CO2 concentration, 55% during 1-h occupancy, and 20% during half an hour occupancy. Therefore, the air-conditioning systems of worship places should be reconsidered in terms of ventilation rates and partial operating to provide comfortable conditions that accommodate different occupancy levels and periods.