Performance Criteria

Performance Criteria
Occupant comfort is the overall objective of the HVAC system, and air distribution is the means
of delivering conditioned air to provide comfort in the room. Comfort is very subjective and can
vary by individual activities and metabolic rates. The principal comfort criteria related to the air
distribution system are temperature mixing and uniformity, drafts that can be created by the
supply outlets, and system noise.
2.1 Temperature Mixing and Uniformity
Temperature in the room is maintained by delivering just the proper amount of air in a manner in
which this air can mix with the air that is already in the room. ACCA (2009) offers guidance for
dry-bulb temperature variances from the thermostat setting during the heating season as
measured at the thermostat to be ±2°F. Similarly the temperature during the heating season in
any room should be ±2°F of the thermostat set temperature. Room-to-room temperature
differences or floor-to-floor temperature differences should be no greater than 4°F in the heating
season. ACCA guidance for room temperature variances from the thermostat setting is ±3°F
during the cooling season.