Quantitative Analysis of the Air Gap Between the Skin and the Clothing Joanna FRACKIEWICZ-KACZMAREK* a , Agnes PSIKUTA a , Renè M. ROSSI a a Empa, Swiss Federal Laboratories for Materials Science and Technology Laboratory for Protection and Physiology, Sankt Gallen, Switzerland; Abstract Thickness of the air gap between the clothing and the human body is a crucial factor for the heat flow and the water vapor and liquid transport occurring in garments. Nowadays, the 3D body scanning technique is commonly used to evaluate the thickness of the air gap. However current methods focus only on either the investigation of the air layers in clothing at discrete number of points or evaluation of the total air volume underneath an ensemble. Therefore, the main aim of this study was to obtain a surface overview of the air gap distribution for modern casual menswear. Detailed mapping of the distribution of the air gap thickness, which is responsible for thermal properties of garments, was done using 3D body scanner and dedicated post-processing software. Moreover, the contact area between the skin and the garment, which is one of the key factors for wicking properties of clothing, was evaluated. This study also analyses the impact of clothing fit on the distribution of the air layer thickness and the contact area. Keywords: air gap, clothing contact area, 3D body scanning 1. Introduction Nowadays, the apparel market offers a large variety of garment types ranging from casual clothes to highly specialized functional clothing. All of them are expected to protect human body against harsh environmental conditions. One of the most important properties of garment is sufficient physiological comfort. It can be provided by balanced heat and moisture transfer between human body, the clothing ensemble and the environment. In this case, physical processes such as dry heat exchange, evaporation and condensation, as well as sorption and water vapor and liquid transfer must be taken into account [1]. The size and shape of the air layers enclosed in the clothing ensemble are major contributors to the magnitude of heat and water vapor exchange. Thus, these processes are influenced significantly by garment displacement caused by clothing design and fit, body posture and movement as well as garment compression induced by wind [2,3,4,5]. The effect of the air gap thickness and its change on thermal and evaporative resistances according to the model presented by Wissler [6] is shown on Fig.1. It indicates that both resistances increase meaningfully with an air gap thickness change of 5 mm. Fig. 1. Thermal (b) and evaporative (c) resistances of the layers in a clothing system consisting of a cotton fabric (227g/m2, 1mm thick) separated by an air gap as in scheme (a) for environmental conditions as follows: Tskin= 34˚C, RHskin= 99%, Tambient= 10˚C, RHambient= 81%. * joanna.frackiewicz@empa.ch, (+41) 071 274 7703, www.empa.ch International Conference on 3D Body Scanning Technologies, Lugano, Switzerland, 19-20 October 2010 107