Determination of human thermal comfort due to moisture permeability of clothes

Abstract

Purpose

The purpose of this paper is to present the determination of human thermal comfort with wearing clothes, with different water vapor permeability. Currently, the predicted mean vote (PMV) equation is widely used to determine thermal sensation scales of human comfort. However, moisture permeability of clothes has been not taken in account where the heat is lost from a human body due to water vapor diffusion through clothes.

Design/methodology/approach

In this study, the heat loss is derived based on the real structure of textiles, causing water vapor pressure difference between air on skin and ambient air. The PMV equation is modified to differentiate a thermal sensation scale of comfort although patterns of clothes are the same. Interview tests are investigated with wearing clothes from three types of textiles: knitted polyester, coated nylon–spandex, and polyurethane, under various air conditions.

Findings

The moisture permeabilities of knitted polyester, coated nylon–spandex and polyurethane are 16.57×10⁻⁹ kg/m² s•kPa, 9.15×10⁻⁹ kg/m²•s•kPa and 2.99×10⁻⁹ kg/m²•s•kPa, respectively. The interviews reveal that most people wearing knitted-polyester clothes have the greatest cold sensations under various air conditions since moisture permeability is the highest, compared to coated nylon–spandex, and polyurethane leather. Correspondingly, the predicted results of the modified PMV equation are close to the actual mean votes of interviewees with a coefficient of determination R²=0.83. On the other hand, the coefficient of determination from the predicted results of the conventional PMV equation is significantly lower than unity, with R²=0.42.

Practical implications

In practice, this quantitative determination on human thermal comfort gives some concrete recommendations on textile selection of clothes for acceptable satisfaction of thermal comfort under various surrounding conditions of usage.

Originality/value

The modified PMV equation effectively determines human comfort on a thermal sensation scale due to the moisture permeability of clothes. To make generic conclusion, experimental results of additional three textiles, such as plain weave/lining polyester, knitted spandex, and open structure polyester, are reported. They confirm that the modified PMV equation effectively determines human comfort on a thermal sensation scale due to the moisture permeability of clothes.

Citation

Ongwuttiwat, K., Sudprasert, S. and Leephakpreeda, T. (2018), "Determination of human thermal comfort due to moisture permeability of clothes", International Journal of Clothing Science and Technology, Vol. 30 No. 4, pp. 462-476. https://doi.org/10.1108/IJCST-09-2017-0138