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Facial skin temperature has been applied to evaluate thermal comfort in a few studies, but the related theoretical basis is not sufficient. We conducted a climate‐controlled experiment in winter. The air temperatures were 12, 15, 18, 21, and 24°C, and the relative humidity was set to 60%. During exposure (140 min), the subjects were in a sedentary state, and their thermal sensation, comfort, and acceptability of perceived thermal environments were documented many times. iButton instruments were used to continuously and automatically record skin temperatures on the forehead, nose, right ear, right cheek, left cheek, left ear, and chin. The measurement accuracy of the corrected skin temperature was within 0.1°C after calibrating each i‐Button. The experimental results showed that the skin temperatures at different measurement points varied significantly. The forehead skin temperature was the highest, whereas the nose, being the facial part, exhibited the lowest skin temperature (except 24°C). The uneven degree of the skin temperature distribution increased as air temperature decreased. Correlation analysis confirmed that the facial skin temperature can be used to evaluate thermal sensation. Nose skin temperature and the average skin temperature of the forehead, nose, and chin are the most suitable indicators of thermal sensation. The correlation between facial skin temperature and the thermal sensation was significantly higher after 15 min of exposure time than that during 0–15 min. This study provides a theoretical basis for using facial skin temperature to dynamically monitor thermal sensations. [ABSTRACT FROM AUTHOR]

A method to develop an adaptive thermal comfort model based on the running mean outdoor temperature for Chinese people was proposed. The determination of two important parameters (neutral temperature and outdoor temperature) in the adaptive thermal comfort model was the focus of this work. A longitudinal survey was conducted from Jan. 2010 to Feb. 2011 in two naturally ventilated office buildings located in Changsha, China. During the survey, the thermal sensation of the subjects was investigated, and the indoor temperature was measured daily. Based on the field data, the neutral temperature and the running mean outdoor temperature were determined. Further, an adaptive thermal comfort model was established by quantifying the relationship between the neutral temperature and the running mean outdoor temperature. The results show that the adaptive thermal comfort model based on the running mean outdoor temperature can well reflect the change of neutral temperature in the two office buildings with the climate of Changsha China. This study provides a reliable method to adjust the adaptive thermal comfort model based on the running mean temperature for Chinese people. [ABSTRACT FROM AUTHOR]

This study investigated the effects of four important microclimate parameters on outdoor thermal sensation and neutral temperature. A long term (almost 2 years) field investigation was conducted at six typical public spaces in Changsha China, with hot-summer and cold-winter climate. During a single investigation of one day (from 9:00 to 18:00), outdoor air temperature, air humidity, global temperature and wind speed were continuously measured at one measuring point. People visiting the public spaces (near the measuring site) were randomly invited to fill out a questionnaire describing their feelings of thermal comfort and other important psychological factors. Based on the field data (7851 samples), relationship between people’s outdoor thermal sensation and the microclimate parameters were quantified. Further, the effect of the microclimate parameters on outdoor thermal sensation and neutral temperatures was analyzed. The results revealed that outdoor microclimate parameters, especially outdoor air temperature, play important roles on outdoor thermal sensation when people stay outdoors. The variation in outdoor microclimate parameters led to the biggest change of outdoor neutral temperature in winter. Seasonal and regional differences in outdoor neutral temperature were found, which reflects different thermal comfort requirements under distinct outdoor microclimate conditions. [ABSTRACT FROM AUTHOR]

Abstract: This study proposed a method to determine time period of thermal adaption for occupants in naturally ventilated building, and analyzed the synergistic and separate feedback effect of the physical and psychological adaption modes on the time period of thermal adaption. Using the method, the values of the time period of thermal adaption were obtained on the basis of the data from a long-term field survey conducted in two typical naturally ventilated offices located in Changsha, China. The results showed that the occupants need to take 4.25 days to fully adapt to a step-change in outdoor air temperature, under the synergistic feedback effect of the physical and psychological adaption modes. The time period of thermal adaption increased to 13 days, if only the feedback effect of the physical adaption mode was accounted for. The difference between the two values of the time period of thermal adaption indicated that the psychological adaption mode can speed up the process of thermal adaption to the variation in the outdoor climate condition. This study presented a new insight into the feedback from the thermal adaption modes to occupant thermal comfort. [Copyright &y& Elsevier]

Abstract: A method was established to evaluate calculation methods of mean skin temperature, in order to find appropriate ones for use in human thermal comfort study. In this method three indexes, including reliability, sensitivity and number of measurement sites, were proposed. Under air temperatures of 21 °C, 24 °C, 26 °C, and 29 °C, 22 subjects’ local skin temperatures (21 sites) and electrocardiograms were measured, and their thermal sensation and thermal comfort were inquired. Human heart rate variability indicated the physiological relation between mean skin temperature and ambient temperature for the sensitivity evaluation. Adopting the evaluation method, 26 types of mean skin temperature calculation methods were evaluated based on the experimental data. The results indicate that a calculation method of mean skin temperature with 10 sites is the most appropriate one, due to its high reliability, excellent sensitivity and fewer measuring sites. When it was applied to reflect thermal comfort, the performance was good. [ABSTRACT FROM AUTHOR]

Extreme thermal environment harms the health of outdoor workers and poses a potential threat to workplace safety. A field survey, including thermal parameter measurements, was conducted at construction sites in South China during the summer of 2019. The relationship between health risk and thermal parameters was obtained. The thermal sensation and satisfaction rate of the workers at different outdoor environmental conditions were analyzed, and recommendations were made based on the comparison of thermal indices. The thermal stress categories of the thermal indices were also investigated. The results suggest that the intensity of working conditions should be reduced when the air temperature is higher than 34 °C; the satisfaction rate of workers was found to be relatively high when the outdoor temperature is lower than 34 °C and the wind speed is greater than 1.3 m/s. Thermal indicators used to evaluate the comfort level of outdoor workers need to be modified according to the local climate and working environment to avoid excessive exposure to high-temperature work environments. • Extreme thermal environment harms the health of outdoor workers. • Thermal parameter measurements were conducted at construction sites in summer. • Labor intensity should be reduced when temperature is higher than 34 °C. • At air temperature <34 °C and wind speed >1.3 m/s, satisfaction rate of workers is high. [ABSTRACT FROM AUTHOR]

To explore how the coldest local thermal sensation (LTS) affects the overall thermal sensation (OTS) after initiating air conditioner, three experimental scenarios (29 → 23 °C, 29 → 25 °C and 29 → 27 °C) were created to simulate the real circumstances in buildings with split air conditioner (SAC). 29 young students were recruited. The skin temperature of 10 body segments along with the LTS of 6 body segments and OTS were measured continuously. Results showed that the foot demonstrated the coldest sensation and the largest skin temperature change, and it exerted stronger influence on the OTS than other body segments. However, the dominance of the LTS of the foot over the OTS showed great dependence on air conditioner set point temperature and air conditioning duration. Moreover, the two aspects of air-conditioner use behavior interacted with each other when affecting the approaching degree of the OTS toward the LTS of the foot. Based on developing and validating models, differences in the approaching degree change trend over air conditioning duration under different set point temperatures were observed, and then the turning point for the set point temperature between the two change trends was identified. When t set < 26 ° C , the OTS quickly approached the LTS of the foot and surpassed it over time. When t set ≥ 26 ° C , the approaching speed significantly reduced. The time-varying and temperature-varying characteristics of the relationship between the OTS and the LTS of the foot provided new insight for understanding air-conditioner use behavior in SAC buildings. • The foot had the coldest local thermal sensation after initiating air conditioner. • Local thermal sensation (LTS) of the foot dominated overall thermal sensation (OTS). • Dominance of LTS of the foot over OTS varied depending on temperature and time. • Temperature and time interacted with each other when affecting the dominance. • A turning point of set point temperature existed between two change trends. [ABSTRACT FROM AUTHOR]

High temperatures are one of the main causes of work safety accidents associated with cognitive impairment. However, the effects of elevated ambient temperature on cognitive performance during moderate-intensity activities are unclear. In this study, subjects (N = 32) were exposed to four different air temperatures, i.e., 26, 30, 33, and 37 °C, and a relative humidity of 70% in a climate chamber. During the experiment, the subjects were required to complete neurobehavioral cognitive tests while walking on a treadmill with an estimated metabolic rate of 165 W/m2. During the 90-min experiment, the tympanic temperature, weight loss, heart rate, and percentage of adjacent inter-beat cardiac intervals differing by > 50 ms (pNN50) were measured. Subjective responses were collected using questionnaires.The accuracy of subjects' responses to the semantic interference and visual perception tests were significantly decreased at 37 °C after 45 min of exercise. Additionally, over the exposure period at 37 °C, the accuracy of various cognitive tests also decreased, while the speed increased. The changes in the cognitive test results at 37 °C were associated with the elevation of the tympanic temperature, heart rate, dehydration rate, and decline of the pNN50. Similarly, the elevated thermal discomfort and intensity of neurobehavioral symptoms were related to these changes.In conclusion, exposure to a temperature of 37 °C for 45 min has a negative impact on the accuracy of personnel with moderate-activity intensity. Therefore, 45 min is recommended as a safe time for continuous work with moderate intensity at 37 °C. • Exposing at 37 °C impaired cognitive performance during moderate-intensity activity. • 45 min is recommended as a safe time during moderate intensity work at 37 °C. • Some specific physiological parameters were related to cognitive performance. [ABSTRACT FROM AUTHOR]

• A dynamic setting temperature that adapts to climate change was proposed. • The method was based on clothing adjustment behavior which adapts to thermal comfort. • The dynamic setting temperature had significant energy saving potential. • The dynamic setting temperature is useful for intelligent control of air-conditioner. Saving energy consumption of air-conditioning is essential to building energy conservation while satisfying the thermal comfort requirements of indoor environment. On the basis of human clothing adjustment behavior, a dynamic setting temperature (DST) that adapts to climate change was proposed in this paper, i.e. indoor air-conditioning setting temperature changes dynamically with outdoor air temperature; furthermore. A method was established to obtain the DST. The daily mean clothing insulation was predicted according to the historical temperature at first, then indoor thermal comfort temperature was calculated based on the variable clothing insulation, and finally the DST was determined. According to the value or range of predicted mean vote (0, -0.5~0.5, -1~+1) corresponding to the thermal comfort, three levels of DST were defined. The corresponding thermal acceptability rates were 95%, 90% and 73%, respectively. A simulation of DST was conducted in a public building in Changsha, China based on meteorological data of 2017. Three levels of DST ranges were obtained, varied from 20.1 to 27.8 °C in level I, 17.8 to 28.7 °C in level II and 15.4 to 29.7 °C in level III, respectively. The simulation results of operational air-conditioning energy consumption shows that the application of DST could save up to 65.5% of energy consumption compared with the traditional fixed setting temperature (FST), and the operational energy consumption decreased by 59.1% due to the application of level-III DST compared with level-I DST. Therefore, the DST proposed in this paper has significant energy saving potential while meeting the thermal comfort requirements. [ABSTRACT FROM AUTHOR]

This study explored the facial skin temperature and thermal sensation of sub-tropically acclimated subjects in summer. We conducted a summer experiment that simulated the common indoor temperatures in Changsha, China. Twenty healthy subjects experienced five exposure conditions: 24, 26, 28, 30 and 32 °C with a relative humidity of 60%. During exposure (140min), the sitting participants documented their thermal sensation, comfort and acceptability of the environment. Their facial skin temperatures were continuously and automatically recorded by using iButtons. These facial parts include the forehead, nose, left and right ears, left and right cheeks and chin. The results found that the maximum facial skin temperature difference increased with air temperature reduction. The forehead skin temperature was the highest. Nose skin temperature is lowest when air temperature is not higher than 26 °C during summer. Correlation analysis confirmed that the nose is the potential facial part that is most suitable to evaluate thermal sensation. Based on the published winter experiment, we further explored their seasonal effects. The seasonal analysis showed that, compared with winter, thermal sensation is more sensitive to indoor temperature changes and facial skin temperatures were less susceptible to thermal sensation changes in summer. Facial skin temperatures were higher in summer under the same thermal conditions. It suggests that seasonal effects should be considered when facial skin temperature can be used as an important parameter for indoor environment control in the future through monitoring thermal sensation. • Uneven degree of skin temperature distribution rises with reducing air temperature. • Nose is the most potential facial part for thermal sensation prediction. • Facial skin temperatures were higher in summer than that in winter. • Thermal sensation is more susceptible to air temperature changes in summer. • Facial skin temperatures were less sensitive to thermal sensation changes in summer. [ABSTRACT FROM AUTHOR]

• Leaf-air temperature difference decreases with increasing environmental temperature. • Hot-dry habitat increases transpirational cooling, decreases leaf warming. • Plants minimize transpirational cooling, facilitate leaf warming in cold forest. • Leaf area and water content play significant roles in physical thermal regulation. The ecophysiological processes of leaves are more related to leaf temperature (Tl) than air temperature (Ta). Transpiration and leaf physical traits enable plants to maintain Tl within a thermal range. However, it is challenging to quantitatively study leaf thermal regulation strategies, due to the complex interaction between thermal effects of transpiration and leaf physical traits. We utilized a 3-T method that compares Tl, Ta, and Tn (the temperature of non-transpiring leaves) investigate thermal regulation strategies of dominant canopy species in four vegetation types, including a savanna woodland, a tropical rain forest, a subtropical evergreen broad-leaved forest, and a temperate mixed forest. Our results indicate that the difference between Tl and Ta decreased as the site mean temperature increased. Transpirational cooling was strongest in savanna woodland, and decreased from the hottest site to the coldest site. Without transpiration, sun-exposed leaves were consistently hotter under sunshine than air. This physical warming effect increased from the hottest site to the coldest site. We observed leaf area, water content and leaf angle played a significant role in physical thermal regulation. The present research quantitatively measured leaf thermal regulation strategies across a temperature and precipitation gradient, which advances our understanding of how plants adapt to their thermal environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Forest ecosystems play an increasingly important role in the global carbon cycle. However, knowledge on carbon exchanges, their spatio-temporal patterns, and the extent of the key controls that affect carbon fluxes is lacking. In this study, we employed 29-site-years of eddy covariance data to observe the state, spatio-temporal variations and climate sensitivity of carbon fluxes (gross primary productivity (GPP), ecosystem respiration (R eco ), and net ecosystem carbon exchange (NEE)) in four representative forest ecosystems in Yunnan. We found that 1) all four forest ecosystems were carbon sinks (the average NEE was − 3.40 tC ha − 1 yr − 1 ); 2) contrasting seasonality of the NEE among the ecosystems with a carbon sink mainly during the wet season in the Yuanjiang savanna ecosystem (YJ) but during the dry season in the Xishuangbanna tropical rainforest ecosystem (XSBN), besides an equivalent NEE uptake was observed during the wet/dry season in the Ailaoshan subtropical evergreen broad-leaved forest ecosystem (ALS) and Lijiang subalpine coniferous forest ecosystem (LJ); 3) as the GPP increased, the net ecosystem production (NEP) first increased and then decreased when the GPP > 17.5 tC ha − 1 yr − 1 ; 4) the precipitation determines the carbon sinks in the savanna ecosystem (e.g., YJ), while temperature did so in the tropical forest ecosystem (e.g., XSBN); 5) overall, under the circumstances of warming and decreased precipitation, the carbon sink might decrease in the YJ but maybe increase in the ALS and LJ, while future strength of the sink in the XSBN is somewhat uncertain. However, based on the redundancy analysis, the temperature and precipitation combined together explained 39.7%, 32.2%, 25.3%, and 29.6% of the variations in the NEE in the YJ, XSBN, ALS and LJ, respectively, which indicates that considerable changes in the NEE could not be explained by variations in the temperature and precipitation. Therefore, the effects of other factors (e.g., CO 2 concentration, N/P deposition, aerosol and other variables) on the NEE still require extensive research and need to be considered seriously in carbon-cycle-models. [ABSTRACT FROM AUTHOR]

Indoor thermal environment design parameters have a significant impact on human thermal comfort, health and building energy consumption. The methods of determining indoor thermal environment design parameters in China and around the world are mainly based on the PMV model. This method often results in certain errors deviations from the actual situation and has difficulty reflecting the differences in the thermal environmental requirements in different climate regions, seasons, building types, etc. This paper proposes a data-driven method based on Chinese Thermal Comfort Database and uses a logistic regression to obtain the indoor air temperature range that 80% of occupants find thermally acceptable under different conditions. The results indicate that the prediction of this model are in good agreement with the actual data and have as higher accuracy in predicting the percentage of thermal acceptability than a linear regression method. This model shows that different regions, seasons, and building types have different acceptable temperature ranges and that the acceptable air temperature ranges are on average 2.0 °C wider than the ISO 7730 and 0.7 °C wider than the GB50736-2012. This method is conducive to the determination of air temperature thresholds and better reflects people's equirements for thermal environment under different conditions. [ABSTRACT FROM AUTHOR]