Evaluation Of Thermal Sensation Research Articles

A method for setting room temperature of district heating in northern China based on local thermal comfort

A method for setting room temperature of district heating in northern China based on local thermal comfort

Effects of thermal environment on body temperature rhythm and thermal sensation before and after getting into bed: A laboratory study in Shanghai, China

Body temperature rhythm serves as a crucial bridge connecting thermal environment and sleep rhythm. While previous studies have extensively confirmed the significant effects of thermal environment on sleep process, a quantitative exploration elucidating the relationships between sleeping thermal environment and body temperature rhythm has persistently been absent. This research aimed to investigate the persistent effects of three stable thermal environments (16 °C, 20 °C and 24 °C) on body temperature rhythm and thermal sensation during complete sleep process. In a laboratory with strictly controlled environment, 14 participants underwent a continuous four-day sleep experiment over a two-month period. Throughout three distinct phases (pre-bed sitting, awake lying in bed, and sleep after lights-off), core body temperature at gastro-intestinal tract, as well as skin temperature at nine specific locations, were continuously monitored. Concurrently, regular questionnaires were employed to periodically collect data on participants’ thermal sensation. The data confirmed that (1) three hours after lights-off, core-to-skin temperature gradient consistently fluctuated around 2 °C across three conditions, and this observation may aid in elucidating the physiological significance of sleeping thermal environment; (2) thermal environment before getting into bed exerted a significant influence on body temperature rhythm and can further regulate the duration of sleep onset latency; (3) bedding system significantly diminished the impact of thermal environment on body temperature rhythm, and future bedding microenvironment deserves more attention; and (4) existing methods for sleeping thermal sensation evaluation varying degrees of limitation, and a novel prediction method was proposed. In general, this study provided valuable insights for the design and regulation of bedroom thermal environment from a thermophysiological perspective.

Effects of individual factors on thermal sensation in the cold climate of China in winter

Due to individual differences in factors, there are differences in thermal sensation among people. This study investigated the effects of three individual factors: age, gender, and BMI on thermal sensation based on the Chinese Thermal Comfort Database. The relationships between the individual factors and thermal comfort were analyzed by thermal sensation evaluation modes and neutral temperatures. The effect of the three factors were explored using Bayesian networks. Furthermore, the reasons why individual factors affect thermal sensation were discussed. The results indicated that there are significant differences in thermal sensation of personnel by age, with the highest thermal neutral temperature of 21.5 °C for the elderly, and the neutral temperature increased with age. There are statistically significant differences in thermal sensation between genders, and female have a 1.3 °C higher thermal neutral temperature than male. The thermal neutral temperature increased with increasing BMI of personnel, and the difference in thermal sensation between different BMI subjects was not statistically significant at the 5 % level. Considering the majority of the people, age has the greatest impact on thermal comfort, followed by gender and then BMI. Individual differences in thermal sensation are caused by physiological, psychological, and lifestyle factors. It is recommended to select subjects with appropriate BMI, while considering the age of the subjects, in order to reduce the effects of individual factors.

Thermal Comfort and Microclimate in Indoor Spaces of Low-rise Residential Buildings in Dry Tropical Climate

The aim of this research is to analyze thermal comfort and microclimate for indoor spaces in low-rise residential buildings in dry tropical climate. The study area is the municipality of Palmar de Varela in northern Colombia. The experimental methodology is based on measuring three microclimatic parameters: air temperature (Ta), relative humidity (RH) and natural ventilation (W). The study assessed the thermal sensation in indoor spaces based on Thermal Sensation Vote (TSV) and Predicted mean vote (PMV). Data gathered from surveys were analyzed with data mining technologies. The findings suggest that suspended ceilings and ceramic tiles aid to the thermal equilibrium of the building, resulting in a 1.1 °C decrease in indoor air temperature. Likewise, the correlation between temperature and wind (r = -0.72; -0.56) indicates that natural ventilation in buildings can alleviate thermal discomfort. Based on the thermal sensation evaluation, the predominant feeling reported by interviewees in indoor spaces was warm (2) in S1 and S2, and slightly warm (1) in S3. In addition, the correlation between air temperature and comfort sensation in indoor spaces (r = 0.64; 0.44) suggests that temperature has a direct impact on thermal sensation votes.

Adaptive thermal sensation evaluation model in tents for Western Sichuan Plateau of China: A field study

The Western Sichuan Plateau (WSP), which is located in the eastern margin of the Qinghai–Tibet Plateau, exhibits a unique climate featuring high altitude, thin air, low air temperature, and strong solar radiation. The local residents have developed a unique thermal sensation as a result of climatic adaptation, which cannot be accurately described using existing thermal sensation evaluation models. Therefore, we conducted a field study of the thermal sensation of the herdsmen living in tents in two typical areas located in the WSP. We measured the thermal environment parameters (air temperature, relative humidity, air speed, and black-globe temperature) on site and simultaneously conducted a questionnaire regarding the activity level, clothing insulation, and thermal sensation of the residents. A statistical regression analysis was performed, and the results showed a difference of 5.7 °C and 3.2 °C between the actual and predicted thermal neutral temperatures of the residents in the WSP during winter and summer, respectively. To improve the prediction accuracy, an adaptive predicted mean vote (aPMV) model incorporated with an adaptive coefficient was established for the WSP. The aPMV model can accurately predicted the thermal sensation levels of the local herdsmen living in tents.

Skin temperature for thermal sensation evaluation - is it valid everywhere?

The application of skin temperature has significantly contributed to the objective evaluation of thermal sensation, but its limitations make it only a temporary solution. In scenarios with stable core temperature, the unexplained individual differences such as gender, age and region etc. Are actually due to the fact that a single skin temperature cannot characterize thermal sensation in a standard and consistent way, when core temperature and thermal sensitivity should be considered in. In scenarios with dynamic core temperature, such as in researches involving step change in ambient environment, exercise state and stage of falling asleep, it's not appropriate to estimate thermal sensation by single skin temperature neither in intra group nor inter group comparison. Considering the current limitations, this paper proposes a comprehensive thermal sensation evaluation index from the perspective of latest thermo-physiology.

Human thermal sensation algorithm modelization via physiological thermoregulatory responses based on dynamic thermal environment tests on males

Background and Objectives: Thermal conditions are changeable in cabin space, where occupants could suffer consecutive self-thermoregulation to such changing thermal stresses. Thermal environment management is expected to be purposefully auto-adjustable for the environment by recognizing individual real-time thermal sensations. Current thermal sensation evaluation models are developed for virtual simulations rather than for realistic scenarios, challenging to evaluate human thermal sensation in the field surveys.Methods: The study constructs a human thermal sensation model via human physiological responses to evaluate the human thermal sensation in the actual vehicle environment. The thermal sensation model forms with exponential functions to clarify the relationship between thermal sensation and pulse rate and blood pressure, which successfully expresses the approximately linear trend around neutral sensation and compensates for the end-points bias. The study set up experimental cases to determine the parameter states in the thermal sensation model. Firstly, subjective thermal sensation scoring was performed by combing with an established seven-point-scale questionnaire survey system for human thermal sensation. Wearable sensors are then applied to measure the human physiological response, including blood pressure BP, pulse rate PR and blood oxygen saturation SpO2.Results: The subjects revealed significantly higher pulse rates (positively correlated) and lower blood pressure (negatively correlated) in the warm chamber than in the cool chamber. The defined parameter change rate effectively reveals the trend of human thermal sensation and avoids the inconsistency of raw physiological response levels. The change rate in PR and MAP between the thermal sensation in cold -3 and hot +3 is about a 10% difference.Conclusions: Based on the thermal sensation model algorithm, model parameters were fitted by the subjects’ thermal sensation voting and the change rate of their physiological responses. With the coefficient of determination (R2) of the regression over 0.8, the proposed thermal sensation model can be employed for human thermal sensation evaluation. The physiological thermoregulatory responses effectively indicate the thermal state of the human body and can be used in thermal environments in conjunction with human smart wearable devices.

Thermal responses and skin temperature to moderate temperature ramps in winter: An office-lab study

In order to explore the acceptable temperature limits of humans in temperature ramps by intermittent heating in the north China, the research was conducted in an office-lab. Four indoor dynamic heating environments with different initial temperatures (15–18 °C) and change rates (0.02–0.18 °C/min) were created. The room temperature gradually rose as people entered the room and divided into two phases by the ramping rates, which was fast in the first phase. During the filed experiments, the variations of overall and local thermal responses were investigated while environmental parameters was monitored. Additionally, the local skin temperatures of participants' hand and ankle were also recorded.The results indicated that the variations of skin temperature from different exposed parts were different. It indicated that humans can make active physiological adjustments according to environmental changes. Moreover, the subject's thermal responses were lagging and affected by the thermal experience. The thermal sensation vote (TSV) was statistically different between the two phases. The calf was the most significant factor on the overall thermal sensation. Furthermore, the TSV significantly affected other psychological responses. The relationships between the TSV and other thermal responses were observed. The thermal sensation evaluation models were established.In summary, the indoor temperature of 16–18 °C is recommended as the initial temperature when the temperature ramping rate is less than 0.2 °C/min. This study gives a theoretical guide for the creation of dynamic indoor thermal environments, which is beneficial for thermal comfort, health, and energy saving.

The influence of structure on the thermal properties of sleeping bags

PurposeTo understand the thermal insulation of four common structures of sleeping bags and factors influencing the thermal insulation as well as the thermal comfort of people who use four kinds of sleeping bag structures.Design/methodology/approachFour samples corresponding to four common sleeping bag structures were made and their thermal properties were investigated through a combination of objective instrument measurement and subjective human subject tests.FindingsThe porosity of the samples and the length of the interlining had a main impact on the thermal resistances of the four sleeping bag structures. The thermal sensation ratings and the thermal resistances had good consistency. There was a strong correlation between human physiological parameters and thermal sensation evaluation. The male and female have significant differences in thermal sensation of different structures of sleeping bags.Originality/valueInstrument measurement and human subject tests were combined to study the thermal properties of sleeping bag structures, which had little attention in the past in research fields.

Thermogenic responses to different clamped skin temperatures in cold-exposed men and women.

Despite many decades of research examining thermoregulatory responses under varying cold stresses in humans, very little is known about the variability in metabolic heat production and shivering activity. Here, we used a novel closed-loop mean skin temperature clamping technique with a liquid-conditioned suit to isolate the effects of mean skin temperature on the subjective evaluation of thermal sensation, heat production, shivering responses, and oxidative fuel selection in young, lean, and healthy men (n = 12) and women (n = 12). Our results showed a skin temperature-dependent increase in metabolic heat production (5.2 ± 1.2 kJ/min, 5.9 ± 1.5 kJ/min, and 7.0 ± 1.8 kJ/min with skin temperature maintained at 31 ± 0.1°C, 29 ± 0.2°C, and 27 ± 0.1°C, respectively; P < 0.0001) and shivering intensity in both men and women [0.6 ± 0.1% maximal voluntary contraction (MVC), 1.1 ± 0.4% MVC, and 2.5 ± 0.7% MVC, respectively; P < 0.0001], including sex-dependent differences in heat production at all three temperatures (P < 0.005). Even when controlling for lean body mass and fat mass, sex differences persisted (P = 0.048 and P = 0.004, respectively), whereas controlling for differences in body surface area eliminated these differences. Interestingly, there were no sex differences in the cold-induced change in thermogenesis. Despite clamping skin temperature, there was tremendous variability in the rate of heat production and shivering intensity. Collectively this data suggests that many of the interindividual differences in thermogenesis and shivering may be explained by differences in morphology and body composition.

Thermal response test analysis of adults and preschoolers under radiant floor heating environment in a hot-summer and cold-winter area

The subjective and objective thermal comfort evaluations of adults and preschoolers in radiant floor heating rooms in a hot-summer and cold-winter area are tested in this article, and the thermal response of the two groups of subjects are analysed using a differential analysis method. The thermal response characteristics of subjects wearing winter clothing with a thermal resistance of 1.02 clo and maintaining a sitting posture were studied at different locations in the office building and different indoor temperatures by combining the characteristics of hot-summer and cold-winter area and the characteristics of office buildings. The results show that when the indoor temperature varies, there was a significant difference in the local skin temperature of the calf of the two groups of subjects (P&lt;0.05). Preschoolers have a more intense overall thermal sensation vote than adults due to the difference in metabolic rate. Different groups of people’s overall thermal sensation vote were linearly correlated. The overall thermal sensation vote of the subjects is linearly related to the indoor operative temperature. The PMV-PPD model is used as the thermal sensation evaluation standard, and there is a considerable difference between the subjective appraisal of preschoolers’ thermal sensations. The PMV-PPD model is not suitable for preschoolers.

Investigation of outdoor thermal sensation and comfort evaluation methods in severe cold area

Comfortable outdoor environment benefits the health of citizens and reduces energy consumption and pollution. This study discusses different outdoor thermal sensation and comfort evaluation methods in severe cold area. The database was from a year-long outdoor thermal comfort survey conducted in Harbin, China. Thermal sensation evaluation was developed using meteorological parameters and three popular thermal comfort indices including Standard Effective Temperature (SET*), Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI). Thermal comfort prediction was developed by the three thermal comfort indices and acceptability. Original thermal sensation scales of SET* and PET were less applicable to predict thermal sensation vote (TSV). Calibrated scales of the three indices were obtained based on linear regression results and probit analysis. The accuracies of calibrated scales of thermal sensation were all below 32.8%. The comfortable thermal sensation range in severe cold area varied from “slightly cool” to “hot”. This calibrated range improved accuracies of thermal comfort predicting by around 20%. The unacceptability appropriate to define comfortable range was 9% on the cold thermal sensation side and 26% on the hot side. Adaptation and local exposure also acted on thermal sensation and comfort apart from factors included in thermal comfort indices. Our results provide practical thermal sensation and thermal comfort scales for severe cold area. The discussions indicate the significance of considering adaptation and local exposure for further improving thermal sensation and comfort predicting.

Predictive modeling for overall thermal sensation of vehicle occupants based on local thermal sensation when warming up

At present, the existing predictive models of overall thermal sensation cannot accurately evaluate occupants’ feelings under vehicle cabin conditions. In this work, aiming at the overall thermal sensation evaluation of vehicle occupants in winter heating condition, the interrelations between the occupants’ local thermal sensations and the overall thermal sensation are analyzed using the experimental results of physical tests. It reveals that the overall thermal sensation is significantly affected by the local thermal sensation at extremities, which are called the extreme local thermal sensations. The overall thermal sensation evaluation model is established using the Support Vector Machine method, which is based on the maldistribution of the local thermal sensations, the extreme local thermal sensation, and the mean value of the local thermal sensations. The prediction accuracy of the training set and the verification set are 80% and 71.11% evidence the application potential of the Support Vector Machine evaluation model.

Study on subjective sensation and physiological reaction with high physical activity influenced by air temperature of stadium

As the main venue for sports training and competition, the thermal environment of a stadium directly could affect the comfort and health of a moving body and sports performance. In this study, the quantitative relationship between ambient temperature and subjective sensation evaluation was established by monitoring the actual thermal sensation evaluation, fatigue sensation cognition and physiological response with high physical activity, under different conditions of ambient temperature. The results show that 90% of subjects can actually accept an ambient temperature range of 18.6°C–26°C. This is 2°C higher than the maximum recommended range in the ISO 7730:2005 thermal comfort standard, reflecting a strong tolerance of the moving human body to low or high temperature environments. A high temperature environment could cause exercise fatigue to occur prematurely. Moreover, the study suggests that the critical point for early occurrence of fatigue sensation in a moving human body is 28°C. The relationship between the environmental temperature and the physiological response was evaluated by mean skin temperature, blood pressure and heart rate of the human body. These are used as evaluation indexes of physiological parameters. Ambient temperature has a significant effect on the objective physiological response of the moving human body, which coincides with the subject’s definition of subjective sensory evaluation to the ambient temperature.

Evaluation of thermal sensation in various outdoor radiation environments

ABSTRACTHuman subject experiments were conducted to investigate the influences of thermal load and thermal sensation under various outdoor radiation environments. The experiments were conducted at locations simulating the application of ground surface materials with different solar reflectance, tall trees, green walls, hedges, and retro-reflective materials. The results revealed that a quantitative evaluation of the heat transfer between the human body and the surrounding environment using the human thermal load may be connected to the thermal sensation felt under various radiation environments. The improved effects of the thermal sensation by the decrease in reflected solar radiation from the ground, the decrease in transmitted solar radiation from the sky, the decrease in infrared radiation from the wall surface, the decrease in reflected solar radiation toward the human body from a window surface, and the shielding of infrared radiation from the ground surface were quantitatively evaluated based on the human thermal load.

Avaliação do conforto térmico ambiente em uma unidade do Centro de Referência de Assistência Social (CRAS)

Os seres humanos apresentam respostas comportamentais e fisiológicas às variações térmicas ambientais e, neste sentido, as pesquisas científicas têm colaborado para o estabelecimento dos princípios da avaliação da sensação térmica das pessoas em relação a um ambiente. Desta forma, a partir dessas observações, o objetivo geral desse trabalho foi avaliar o conforto térmico de uma recepção às famílias em uma unidade do Centro de Referência de Assistência Social (CRAS) no município de Barra do Bugres – MT. O registro dos dados de temperatura e umidade relativa do ar foi realizado para a estação quente-úmida por meio do instrumento Arduino UNO e, como método de tratamento desses dados, fez-se o uso do programa Microsoft Excel, versão 2016 e o AnalysisBio, versão 11.0 para a conversão das Cartas Psicométricas de Givoni, visando identificar uma sensação térmica favorável ou não do ambiente. Foi constatada a influência das tipologias dos materiais construtivos usados ao observar que a maioria destes influenciam nos resultados expostos às condições de conforto, exigindo-se sombreamento em quase 99,4% das horas coletadas e ventilação no ambiente para melhoria da qualidade e da renovação do ar interno. Portanto, conclui-se que o ambiente apresentou um desconforto térmico durante a maior parte das análises por períodos, devendo haver uma preocupação quanto à escolha dos materiais na concepção dos projetos de instalações, buscando minimizar fatores que possam interferir no rendimento metabólico humano no exercício de suas funções, identificando estratégias e alternativas viáveis e de baixo custo à realidade da região de estudo.

Assessment of brain mechanisms involved in the processes of thermal sensation, pleasantness/unpleasantness, and evaluation

The conscious perception of thermal stimuli is divided into two categories: thermal sensation (i.e., discriminative component) and pleasantness/unpleasantness (i.e., hedonic component). There have been very few studies which clearly dissociated the two components. The aim of the present study was 1) to identify brain regions involved in perception of thermal stimuli per se, dissociating those related to the two components, and additionally 2) to examine brain regions of the explicit evaluation processes for the two components. Sixteen participants received local thermal stimuli of either 41.5 °C or 18.0 °C during whole-body thermal stimuli of 47.0 °C, 32.0 °C, or 17.0 °C. The local stimuli were delivered to the right forearm with the Peltier device. The whole-body stimuli delivered through a water-perfusion suit was aimed to modulate thermal pleasantness/unpleasantness to the local stimulus. The local stimulation at the same temperature was conducted five times with 30-s intervals. Brain activation was assessed by functional magnetic resonance imaging (fMRI), and the participants were asked to report their ratings of thermal sensation and pleasantness/unpleasantness following the cessation of each local stimulus. Local thermal stimulation activated specific brain regions such as the anterior cingulate cortex, insula, and inferior parietal lobe, irrespective of the temperature of local and whole-body stimuli; however, no specific activation for hot or cold sensation was observed. Different brain regions were associated with pleasantness and unpleasantness; the caudate nucleus and frontal regions for pleasantness, and the medial frontal and anterior cingulate cortex for unpleasantness. In addition, the explicit evaluation process for the discriminative and hedonic components immediately following the cessation of local stimulus involved different brain regions; the medial prefrontal cortex extending to the anterior cingulate cortex, insula, middle frontal cortex, and parietal lobes during the explicit evaluation of thermal sensation, and the medial prefrontal cortex, posterior cingulate cortex, and inferior parietal lobes during that of pleasantness/unpleasantness.

Prediction of Outdoor Human Thermal Sensation at the Pedestrian Level in High-rise Residential Areas in Severe Cold Regions of China

The residential areas, as a city’s basic unit, have the closest connection with people’s living environment; the outdoor thermal sensation of residential areas directly affects people’s physical and mental health. This study aims to reveal the relationship between the high-rise residential areas’ building density and wind projection angle, with the winter pedestrian thermal sensation in severe cold regions. In this study, the prediction model of pedestrian-level wind chill temperature of high-rise residential areas is established by using the existed prediction model of the mean pedestrian-level wind velocity ratio of high-rise residential areas and the standard values of air temperature and wind velocity from urban meteorological stations, to perform the quantitative analysis of pedestrian thermal sensation of high-rise residential areas in severe cold regions in winter. Based on this, the winter pedestrian thermal sensation evaluation for the high-rise residential areas of six major cities in the severe cold regions of China is performed by using the prediction model. This paper provides the quantitative guidance and evaluation basis for the high-rise residential areas planning in severe cold regions.

Evaluation of thermal sensation among customers: Results from field investigations in underground malls during summer in Nanjing, China

Previous studies on thermal sensation have mainly focused on offices and residential buildings, but rarely on underground malls. In this paper, field studies on thermal environment in six underground malls were conducted in Nanjing, China, particularly from customer's perspective. The results showed that when indoor operative temperature (Top) was more than 26 °C, the customers' mean thermal sensation votes (TSV) were lower than PMV. It indicated that they may perceive the warmth to be less dramatic than PMV predicted in underground malls. When Top was below 24 °C, a higher percentage of customers desired a warmer indoor environment. Customers' thermal acceptability (TA) decreased significantly when relative humidity (RH) increased from 65% to 75% (p<0.01), and significant changes of TA were recorded when air velocity increased from 0.2 m/s to 0.4 m/s under RH ranging from 70% to 80%. The customers' duration time (DT) in malls were different, the mean TSV of customers with DT less than 1 h was significantly different from other customers' TSV (p < 0.01). Among customers, those who had spent less than an hour in underground mall perceived the thermal environment to be cooler. In addition, the customers' TSV under outdoor-indoor temperature drop in entrance regions in two underground malls was compared. It showed that setting the transitional space with non-air-conditioned system or at a slightly higher temperature would improve the customers' thermal sensation and save energy.

Evaluation of Thermal Sensation in Office Buildings: A Case Study in the Mediterranean

The existing institutional frameworkis expressing, both in Europe and in Greece, the strong drive for improving the existing buildings stock, by means of compulsory measures, as buildings account for almost 40% of the primary energy consumption in Europe. Especially, when referring to office buildings, the existence of increased cooling requirement accounts for very high consumption values (up to 60% of the overall), whilst at the same time the occupants experience significant levels of discomfort. Therefore, the occupants’ well-being as well as their productivity are affected.Within the framework of this study, an evaluation of both thermal comfort and indoor air quality conditions is carried in two office buildings. Both buildings are located in northern Greece and were constructed after 1980 and before 2010, in accordance with the first Greek Thermal Insulating Regulation. In situ measurements were carried during the winter period for the one building and the summer for the other. The measured parameters are the air temperature, the humidity levels and the levels of CO2 emissions specifying the indoor conditions. Furthermore, a revealed preference survey was conducted in order to specify the parameters affecting the occupants’ reaction concerning the indoor thermal conditions through the usage of regression model analysis.The interpretation of occupants’ reaction to indoor conditions and the human's sensation of thermal comfort,based on monitoring the existing environmental conditions and determining probable correlation with individual characteristics are very promising.