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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.

The mechanism of human thermal comfort is important for building a comfortable and healthy indoor environment. This paper analyzes human heart rate variability (HRV) at different thermal comfort levels and discusses the mechanism of human thermal comfort. A total of 33 subjects were divided in 3 groups. Under air temperatures of 21, 24, 26, 28, 29, and 30 degrees C, the subjects' electrocardiogram was recorded for 5 min. HRV (the ratio of absolute powers in low- and high-frequency bands, LF/HF ratio) was analyzed. LF/HF at discomfort level were significantly higher than that at comfort level (P < 0.05), despite the same thermal sensation. The results indicate that sympathetic activity plays an important role in subjects' thermal discomfort and the LF/HF ratio may be used as an indicator for human thermal comfort.

Gender difference in thermal comfort for Chinese people was investigated through two laboratory experiments. Both subjective assessment and objective measurement were taken during the experiment. Skin temperature (17 points) and heart rate variability (HRV) were measured in one of the experiment. Our results show that there are gender differences in thermal comfort for Chinese people. Correlation of thermal sensation votes and air temperature and vapor pressure shows that females are more sensitive to temperature and less sensitive to humidity than males. Subjective assessment, skin temperature and HRV analysis suggest that females prefer neutral or slightly warmer condition, due to their constantly lower skin temperature and the fact that mean skin temperature is a good predictor of sensation and discomfort below neutrality. Female comfortable operative temperature (26.3 degrees C) is higher than male comfortable operative temperature (25.3 degrees C), although males and females have almost the same neutral temperature and that there is no gender difference in thermal sensation near neutral conditions.

The definition of a good indoor climate is important to the success of a passenger rail coach, not only because it will decide its energy consumption and thus influence its sustainability but also because good comfort for long journeys is essential. A survey in a coach investigating the thermal and air quality environment was undertaken. The intention is to use the results to optimise the control of the ventilation system to provide an indoor climate that passengers will find comfortable. Field surveys were carried out in long–haul rail sleeper cars in China under real travelling conditions. In this study, seven main parameters were surveyed, including thermal comfort, relative humidity, air quality level, clothing, and environmental preference, etc. Returned questionnaires, 91 in total, reported responses to the environment within the coach. The majority of subjects reported that the air quality in the coach was average or good, and most of them voted the air environment to be acceptable. Most pa...