Clothing

Clothing is viewed as an additional layer on the skin establishing a direct contact between skin and clothing. The clothing only influences the dry and wet heat fluxes of the passive system. The clothing does not influence the active system.

The influence of clothing on the dry heat flux is taken into account through a thermal efficiency factor $F_{{TE}_j}$. This factor quantifies the influence of the insulation through clothing in relation to the dry heat transfer coefficient:

The thermal efficiency factor ranges between 0 and 1, where 1 corresponds to a unclothed condition. The factor $F_{SURF}$ takes the increase in size of the surface due to clothing into account. According to DIN ISO 7730, $F_{SURF}$ for a skin element is computed as follows:

where $I_{CLOTH}$ is the isolation factor clothing in m²K/W.

Including $F_{{TE}_j}$, the dry heat flux becomes:

The temperature of the clothing surface $T_{{CLOTH}_j}$ is:

A further effect of clothing is to restrain evaporation of moisture on human skin. To account for this effect, a factor $F_{FD}$ is defined that reflects the water vapor permeability of clothing.