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Purpose – The purpose of the paper is to simulate the effect of clothing insulation and activity on the interaction between the human body and the environment. Design/methodology/approach – A thermo-physiological model, integrated into a Fluent CFD software package is applied. The temperature of the skin surface, clothing surface and heat flux (dry and total heat flux) through layers of clothing with different insulation level are numerically investigated in function of the clothing insulation and the different activities performed indoors. Findings – The increase of the clothing insulation leads to increase of both skin and clothing temperature. Higher temperature difference ΔT between the room temperature and skin temperature provokes more dynamic change of the skin temperature and decreases the thermal comfort of the person. The increase of the metabolic rate, however, leads to more uniform skin temperature, regardless the temperature difference ΔT. With the increase of the clothing insulation for a constant metabolic rate the total heat flux remains constant, but the dry heat flux decreases, while the evaporative heat flux increases. Originality/value – The joint influence of clothing insulation and indoor activities on the thermal interaction between the body and the environment is assesses using a thermo-physiological model, integrated in a CFD software package.

The objective of the paper is to demonstrate the importance of the unsteady Computational Fluid Dynamics (CFD) simulations and long-term measurements for the reliable assessment of thermal comfort indoors, for proper categorization of the indoor thermal environment and for identifying the reasons for complaints due to draught discomfort. Numerical simulations and experimental measurements were applied in combination to study ventilation in a field laboratory, a university classroom with a controlled indoor environment. Strong unsteadiness of the airflow was registered both in the unsteady RANS results and the real-scale long-term velocity data measured with thermo anemometer. Low-frequency high-amplitude velocity fluctuations observed lead to substantial time variation of the draught rate. In case of categorization of a thermal environment, the point measurements or steady-state RANS computations would lead to wrong conclusions as well as they cannot be used for identification of the reasons for people’s complaints due to draught discomfort if strong unsteadiness of the airflow exists. It is demonstrated that the length of the time interval for draught rate (DR) assessment may not be universal if low-frequency high-amplitude pulsations are present in the room airflow.

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