Calculation of clothing insulation and vapour resistance

Abstract

Based on a physical model, in which a human is depicted as a collection of appropriately sized cylinders, clothing insulation and vapour resistance are calculated for standing persons in still air, when the clothing ensemble thickness, total fabric thickness, number of clothing layers and number of trapped air layers are specified for each cylinder. Specific knowledge of the clothing material is not required, except when coatings of films are involved. The resulting reference values for clothing insulation and vapour resistance are accurate to a standard deviation of 0·011thinsp;m²K/W and 1·8 mm of air equivalent, respectively, compared to thermal manikin measurements. The reference values are modified for sitting, walking, and cycling at various rates, and for the combined effect with wind. The formulas are regression equations on a database of literature. The resulting total insulation and vapour resistance are accurate to 0·022 m²K/W and 3·6 mm of air equivalent, respectively. The physical model, which is available as software, is a challenge to existing methods for the determination of insulation and vapour resistance with respect to simpleness and accuracy.

Keywords:

• Clothing insulation
• Vapour resistance
• Predictive model
• Wind
• Activity