The Effect of Lower Opening on Thermal Insulation of Clothing System. Measured by Simulated Skin.

Abstract

Thermal insulation and ventilation capacity of clothing are one of the most important properties concerning the thermal comfort of the human body. Though both of above properties are needed for winter clothing, it is difficult to get a clothing with both good thermal insulation and good ventilation capacity only by fabric properties like thermal conductivity and air permeability because a clothing with good ventilation capacity has little thermal insulation and vice versa. This paper aimed to find a most compromising condition by changing clothing constructive factors like size of air space and open-closed situation of lower opening of air space of clothing. Ventilation capacity was affected by both air permeability of a clothing material and an open-closed situation of lower opening. It was already made clear in a previous paper _??_1_??_ that the air permeability of clothing material did not affect on heat transfer of clothing when the human model was standstill, the size of air space of clothing was more than 10mm and there was no forced flow in surroundings. So ventilation could be caused only by the penetration through lower opening. By experiments using vertical hot-plate and theoretical calculation, follows were clarified. Open-closed situation of lower opening affected on thermal insulation largest when the size of air space was 10mm. Thermal efficiency of closed case was 1.45 times as large as that of open case. However, from a viewpoint of ventilation, an open situation was desirable. If this situation occurred in a real clothing system, an unevenness of thermal insulation along the height would increase chilliness near “legs”.