The effect of wind,body movement and garment adjustments on the effective thermal resistance of clothing with low and high air permeability insulation

Abstract

Using a thermal manikin, the total clothing thermal resistance (I_T) of two clothing ensembles with the same air-impermeable outer layer but with either high or low air permeability insulation was determined at three different walking (0, 1 and 2.5 km.h⁻¹) and wind (0.1, 1 and 2.5 m.s⁻¹) speeds. Three clothing ‘configurations’ (outer garment sealed, outer garment open, outer and mid layer garment open) were also tested. The I_T of the high-permeability insulation was lower than that of the low-permeability insulation, indicating more heat transfer by radiation and the possibility of natural convection between clothing layers. When the outer garment was opened to favor ventilation, the I_T of the high-permeability insulation was reduced by between 15% (surface-weighted average) and 25% (locally) more than that of the low-permeability insulation, but when the outer garment was ‘sealed’, the I_T of the high-permeability insulation was not reduced by a greater extent. The use of high-permeability insulation may allow clothing designers to create more comfortable clothing by encouraging ventilation, particularly by creating localized cooling.