Air movement and thermal comfort

Abstract

ASHRAEecent HVAC design innovations, energy conservation concerns and new laboratory data on drafrs have brought substantial attention to the issue of acceptable lEvels ol air movement in office environments.Air movement may provide desirable cooling in u,alm conditions, but it may also increase the risk of unacceptably cool drafts.Detectable air movement may be perceived by the occupants as providing freshness and pleasantness to the breathing air, ya it may also be perceived as annoying.Clearlll a specific air speed has many possible physiological and subjective consequences.These range from a pleasant sense of coolness to an unpleasant sense of dnft, depending on the air emperaturg mean radiant ternpeftlturg humidit"v, clothing, metabolic rate and air movement preference of the occupant.Since the turn of the century, ASH-RAE and thermal comfon rerarchers have worked to define levels of air movement that are accepuble to the widest possible group oi indiriduals within an evolving architectural serting, and to incorporate these results into an indoor elvironmental standard.This anicle outlines the current state of this discussion.Referenceis also made to research investigating the effect of air movement on thermal comfort and the dwelopment of air velocity limits in the latesr ASHRAE thermal comfort standard.