The Effect of Air Movement. Air movement influences the bodily
heat balance by affecting the rate of convective heat transfer between the
skin and air and the rate of bodily cooling through evaporation of skin
moisture. The air velocity lines on Figure 4 show the extent to which
increased air movement can increase the range of temperatures and humidities
in which people will feel comfortable.
Required Air Velocities for Human Comfort. Minimum rates of
ventilation are based on requirements for health (oxygen supply and removal of
contaminants.) Ventilation, natural or mechanical, is required at all times.
Refer to NAVFAC DM-3.03 for minimum rates by occupancy and building type. The
maximum rates of interior air velocity are defined by factors other than human
physiological comfort alone.
The upper limit of indoor velocity depends on building type and
use. For offices and commercial spaces, the limit is 160 fpm (0.8 m/sec), the
point at which loose paper, hair and other light objects may be blown about.
In heavy industrial spaces, this limit is not as important as the removal of
toxic fumes, heat or other deleterious conditions, and higher indoor
velocities (up to 300 fpm or 1.5 m/sec) are acceptable. Maximum indoor air
velocities for residential buildings are between these extremes. A practical
upper limit is 197 fpm (1.0 m/sec), which is shown on the bioclimatic charts
contained in Appendix A.