Resultant clothing insulation: a function of body movement, posture, wind, clothing fit and ensemble thickness

Abstract

The individual and combined effects of sitting, walking at two speeds and three wind speeds on the insulation value of three clothing ensembles were determined on four subjects (two with loose clothing fit and two with tight clothing fit). Subjects were wrapped in synthetic foil before dressing in order to avoid sweat evaporation and so increase the accuracy of the measurement, while reducing the time needed to reach a steady state. All influences (posture, movement, wind and clothing fit) show significant effects on the clothing insulation. The insulation of coveralls is more reduced for sitting than two piece ensembles. Movement and posture mainly influence the intrinsic clothing insulation, whereas wind mainly affects the surface air layer insulation. Tight clothing fit shows a 6–31% lower insulation than loose fit. Thick clothing shows stronger reductions in insulation due to posture and movement than ensembles with low insulation values. These effects are described with a linear regression equation for each activity/posture. Walking speed also has a linear effect. The wind effect on the heat transfer coefficient h (=1/I_tot can be described with a square root function. These regression equations provide a tool for the correction of the clothing insulation in the standing situation without wind to the resultant insulation for the actual conditions in the real situation.