Clothing convective heat exchange - Proposal for improved prediction in standards and models

Convection is an important determinant for both sensible and evaporative he at exchange. Heat transfer by convection for normal boundary conditions is readily described by simple po,ver functions. Clothing affects convection i n carious ways and existing characterisation of clothing by its static insu lation values produces inaccurate prediction of sensible heat exchange, eve ntually leading to erroneous risk assessment. The present paper reviews var ious methods for evaluation of clothing convective (sensible) heat exchange , Based on available data, two equations are proposed for determination of the reduction of the total insulation values obtained under static, still w ind conditions as a consequence of wind and walking effects. The equations apply from 0 to 1.84 do, from 0.2 to 3 m/s and for walking speeds up to 1.2 m/s, The equations are incorporated in ISO 7933 to provide a more realisti c and accurate prediction of sensible heat transfer through clothing, (C) 1 999 British Occupational Hygiene Society. Published by Elsevier Science Ltd . All rights reserved.