The interaction of clothing ventilation with dry and evaporative heat transfer of jackets: the effect of air and vapor permeability

PURPOSE. This paper aims to investigate the effect of air and vapor permeability of jacket materials on ventilation, heat and moisture transfer. DESIGN/METHODOLOGY/APPROACH. Clothing ventilation (V), thermal insulation (I) and vapor resistance (Re) of three jackets made of different materials (normal textile, PVC and ‘breathable’ membrane coated textile), worn on an articulated thermal manikin in a controlled climate chamber, were measured under various conditions respectively. The various conditions of microenvironment ventilation were created by making the manikin stand and walk, combined with three wind speeds of < 0.2, 0.4 and 2.0 m/s respectively. FINDINGS. In the condition without any forced convection, the air permeability makes no big difference to dry and evaporative heat transfer among the jackets, while the vapor permeability plays a big role in the evaporative heat loss. In the condition with forced convection, the dry heat diffusion is strongly coupled to the evaporative heat transfer in air and vapor permeable textile material. RESEARCH LIMITATIONS/IMPLICATIONS. The effects of ventilation on heat and moisture transfer varies because of different ways of ventilation arising: penetration through the fabric is proven to be the most effective way in vapor transfer although it does not seem as helpful for dry heat diffusion. ORIGINALITY/VALUE. The achievements in this paper deepens our understanding of the process of the dry and evaporative heat transfer through clothing, provides clothing designer guidance to choose proper materials for a garment, especially work clothing.