Research on Thermal Comfort Equation of Comfort Temperature Range Based on Chinese Thermal Sensation Characteristics

Abstract

Thermal comfort is a subjective experience in which the human body feels satisfied with the thermal environment. The human thermal sensation is mainly related to the heat balance of the whole body. This balance is not only affected by environmental parameters such as air temperature, average radiant temperature, wind speed and air humidity, but also by human activities and dress. Local thermal discomfort includes evaluation indexes such as draft, vertical temperature difference, ground heating and cooling, and radiation asymmetry. When these parameters are estimated or measured, the overall thermal sensation of the person can be predicted by calculating the predicted mean thermal sensation index (PMV). Internationally, the currently accepted standard for predicting and evaluating indoor thermal environment comfort is ISO 7730-2005 and American Standard ASHRAE 55-2013. In the ISO 7730-2005 standard, the comfort is evaluated for the steady-state and non-steady-state thermal environments. The evaluation of the steady-state environment mainly evaluates the PMV, PPD indicators and local thermal discomfort. The unsteady environment is mainly evaluated from indicators such as temperature cycle and drift. In terms of thermal comfort evaluation, after extensive experiments, the researchers tried to link the four elements that make up the thermal environment (air temperature, humidity, wind speed and ambient average radiant temperature) to the thermal sensation of the human body. However, heat balance is not a sufficient condition for human thermal comfort. The Fanger thermal comfort equation and its evaluation indicators have their limitations. Studies have shown that the actual thermal sensation of the test subjects is significantly higher than the PMV through the thermal comfort survey of winter and summer residential buildings, and pointed out that there is a lack of equations. To this end, this paper carried out a test for the thermal sensation characteristics of Chinese people, conducted thermal comfort tests on nine environmental conditions of refrigeration and heating through 40 subjects of different ages, and determined the differences in thermal sensory characteristics of human body at different ages, analyze the test results and correct the PMV equation according to the results to make it more in line with the physiological characteristics of Chinese people. The test results show that the thermal sensation index of children and the elderly is significantly different, the children’s thermal sensation is obviously cold, while the elderly are obviously warm, and the thermal sensation characteristics of adults with different genders are also different. Men are more like cold than women. When testing for the elderly and children, gender has little effect on the characteristics of thermal sensation, and there is no obvious difference between hot and cold in different genders.