Influence of human body geometry, posture and the surrounding environment on body heat loss based on a validated numerical model

For accurate prediction of human thermal comfort in indoor space, a fully validated human body-environment interface model is the key factor. In this study, a numerical model for heat transfer simulation between the human body and the environment was developed. Three parameters, including air speed, air temperature, and total heat transfer coefficient at the body surface, were validated against experiments including a manikin placed in a climatic chamber. Based on the verified model, a set of human body-environment parameters were investigated to quantify their relevance for thermal simulations. The parameters included three body geometries with different simplification levels, three body postures, and three kinds of environments differing in room configuration, size, and wall emissivity. The investigations revealed that body geometry simplification had only a moderate influence on overall heat transfer between the body and environment, while greatly influencing local heat transfer. Body posture showed a more prominent impact on heat transfer than the geometry, especially on the radiative heat transfer, due to the view factor change caused by local body orientation. The room configuration largely influenced the airflow pattern and, thus, convective heat transfer, while room size and wall emissivity only had an influence on radiative heat transfer. A similar environmental setup and body posture with the real situation would be suggested as the premise for the body-environment modelling work. The validated numerical model, along with the set of body-environment parameters, can be used for a large range of investigations on human physiological response in varying thermal environments.