This paper is a study of the correlation of the thermal resistance (Rct ) and the evaporative resistance (Ret ) in vertically and horizontally oriented air gaps by using the portable Permetest skin model. Experiments were done in a climatic chamber; an isothermal condition for Ret tests and non-isothermal condition for Rct tests. Foamed polyethylene air gap distance rings were prepared with a thickness of 2, 4 and 5 mm and their combinations to simulate the air gap distance from 0 to 16 mm which is more than the expected average gap in clothing systems. Test samples were woven fabric of 100 percent cotton, 100 percent polyester and their blends plus 100 percent of polypropylene, all have similar weight and structure. Results showed that with the increasing thickness of the air gap, Rct increased in a polynomial trend and Ret in a linear proportional rate up to 12 mm then started to change due to the effect of free convection and the different properties of materials. The surprising positive observation is that results from the horizontally and vertically oriented air gaps are very similar, and most of the results from the vertical air gap are slightly lower than the results from the horizontal air gap in all materials.

This paper is a comparison of water vapor resistance (Ret) measured using the Permetest skin model and Tore sweating thermal manikin, i.e. 2D versus 3D methods; and to study the relationship between them. Three materials and five air gap distances were used for the measurement between these two devices, the test conditions in the climatic chambers were set up according to the ISO standard of each measurement method. Results of the correlation coefficient of three materials showed that they all had a strong increasing trend between Permetest and the sweating thermal manikin. From the regression analysis, the P-value of all three materials showed that P< 0.05 and 100% cotton R2=0.83, 50% cotton 50% polyester R2=0.91, 100% polyester R2=0.99. However, Ret resulting values from each device slowed down after 12mm air gap distance.