Study on the allowable fluctuation ranges of human metabolic rate and thermal environment parameters under the condition of thermal comfort

People can keep good thermal comfort when they participate in different intensity activities at a certain environment. But their thermal comfort changes greatly even with a slight change of activity intensity at other environment. It means that people's allowable fluctuation range of metabolic rate differs at different environments. Furthermore, the fluctuation ranges of thermal environment parameters also have different impacts on thermal comfort. Based on the body heat balance equation, this paper explored the influencing factors of the allowable fluctuation range of metabolic rate and the comfortable ranges of thermal environment parameters. The mathematical model between thermal environment parameters and the allowable fluctuation range of metabolic rate was established through the adoption of orthogonal experimental design test and multiple regression analysis. To verify the validity of theoretical results, questionnaire surveys were conducted in Changsha. The results showed that the air temperature is the most significant factors which affect the allowable fluctuation range of metabolic rate within the thermal comfort zone, the next are relative humidity and air velocity. There is a strong linear relationship between these three factors and the fluctuation range of metabolic rate. Combining the established model and questionnaire surveys, the comfortable ranges of temperature and relative humidity were obtained. These conclusions not only can provide a simple and feasible method to determine the allowable fluctuation range of metabolic rate in a given weather condition, but can also provide valuable references to set a standard for air-conditioning design parameters and indoor operating parameters according to different functional architectures.