Interactions of the surface heat and moisture transfer from the human body under varying climatic conditions and walking speeds

The surface heat and moisture transfer from the human body are normally characterized by the thermal insulation and moisture vapor resistance, which are important parameters in environmental engineering. In the past, due to the limitation of measurement technology, simultaneous measurement of these two parameters was not possible and hence there is a lack of clear understanding on the interaction of surface heat and moisture transfer. In this paper, through the experimental measurements on a newly developed sweating/non-sweating fabric manikin (named WALTER) under varying climatic conditions and "walking" speeds, we show that the surface thermal insulation is little affected by moisture transfer. The surface moisture vapor resistances measured under isothermal conditions tend to be greater than those measured under non-isothermal conditions, especially when the wind velocity is less than 2.0 m/s. The Lewis Relation holds under non-isothermal conditions, but should be corrected under isothermal condition when the wind velocity is small.