Clothing insulation and temperature, layer and mass of clothing under comfortable environmental conditions

Abstract

This study was designed to investigate the relationship between the microclimate temperature and clothing insulation (I cl ) under comfortable environmental conditions. In total, 20 subjects (13 women, 7 men) took part in this study. Four environmental temperatures were chosen: 14°C (to represent March/April), 25°C (May/June), 29°C (July/August), and 23°C (September/October). Wind speed (0.14ms-1) and humidity (45%) were held constant. Clothing microclimate temperatures were measured at the chest (T chest ) and on the interscapular region (T scapular ). Clothing temperature of the innermost layer (T innermost ) was measured on this layer 30 mm above the centre of the left breast. Subjects were free to choose the clothing that offered them thermal comfort under each environmental condition. We found the following results. 1) All clothing factors except the number of lower clothing layers (L lower ), showed differences between the different environmental conditions (P<0.05). The ranges of T chest were 31.6 to 33.5°C and 32.2 to 33.4°C in T scapular . The range of T innermost was 28.6 to 32.0°C. The range of the upper clothing layers (L upper ) and total clothing mass (M total ) was 1.1 to 3.2 layers and 473 to 1659 g respectively. The range of I cl was 0.78 to 2.10 clo. 2) Post hoc analyses showed that analysis of T innermost produced the same results as for that of I cl . Likewise, the analysis of L upper produced the same result as the analysis of the number of total layers (L total ) within an outfit. 3) Air temperature (t a ) had positive relationships with T chest and T scapular and with T innermost but had inverse correlations with I cl , M total , L upper and L total . T chest , T scapular , and T innermost increased as t a rose. 4) I cl had inverse relationships with T chest and T innermost , but positive relationships with M total , L upper and L total . I cl could be estimated by M total , L upper , and T scapular using a multivariate linear regression model. 5) L upper had positive relationships with I cl and M total , but L lower did not. Subjects hardly changed L lower under environmental comfort conditions between March and October. This indicates that each of the T chest , M total , and L upper was a factor in predicting I cl . T innermost might also be a more influential factor than the clothing microclimate temperature.