Supply Outlets

Supply Outlets
2.2.1 Impact on Uniformity
When selecting supply outlets, the designer must consider the “occupied zone” of the space to be
2 feet off walls and 6 feet above the floor to avoid drafts. Drafts caused by airflow within the
occupied zone can be considered a comfort issue. The amount
of airflow that may be perceived as a draft can be relatively
low. Air at a velocity of 15 feet per minute may allow smoke
to hang in the air, whereas a piece of paper may blow off a desk at an air velocity of 65 feet per
minute. The target terminal velocity or the velocity at the useful end of an air stream is between
50 and 75 feet per minute; therefore, if this air stream is directed into the occupied zone, a
complaint of a draft is likely.
Pressure loss associated with the supply outlets must be considered when selecting the type of air
outlet and must be added to the entire duct run pressure loss.
The proper amount of air is determined by the room-by-room heating and cooling loads. Too
little air delivered to a room results in underheating or undercooling, whereas too much air
delivered to a room results in overheating or overcooling. To maintain a uniform temperature
and to avoid stratification, the supply air must also adequately mix the air in the room.