Moisture load and airflow
Supply Air
送风
Supply air is the air delivered by a ventilation, heating, cooling or air-conditioning system to a space.
- Abbreviations
- SA
- Aliases
- delivered air
QUANTITY, SYMBOL AND UNIT
Quantity / objectSupply air
UnitNot applicable
Definition
Supply air is the air delivered by a ventilation, heating, cooling or air-conditioning system to a space.
It can contain outdoor air, recirculated air, transfer air or a combination. In dehumidification work, the useful state point is normally specified at a defined unit outlet, duct location or room inlet, because heat gain and leakage can change the air before it reaches the space.
Relations and distinctions
Supply and ventilation air
Supply air is the whole delivered stream; ventilation air is the outdoor-air portion provided for a ventilation requirement.
Supply and process air
Supply air is defined by delivery to a space. Process air is defined by passing through a dehumidification process and may or may not be delivered directly to that space.
Engineering meaning
- Specify supply airflow together with dry-bulb temperature and a moisture property at a named location.
- Check duct heat gain, leakage, mixing and distribution before treating unit leaving air as the room supply condition.
Common misconceptions
MisconceptionSupply air is always 100% outdoor air.
Accurate explanationA supply stream may be any stated combination of outdoor, recirculated and transfer air.
Application boundaries
- The term does not define one universal supply temperature, RH or dew point.
- Supply-air condition alone does not prove uniform conditions throughout the served space.
Supporting sources
-
ASHRAE / SRC-ASHRAE-TERMINOLOGY-VENTILATION
ASHRAE Terminology: Ventilation Air and Supply Air ↗
Live terminology database / Entry: supply air
Supports: Supply air is air delivered to a space; Supply air may combine outdoor, recirculated or transfer air; Only the outdoor-air portion of the supply stream is replacement air
Maintenance record
Supply Air
- Maintained by
- Yakeclimate Engineering Team
- Authoritative sources verified
- August 3, 2026
- Terminology checked
- August 3, 2026
- Last updated
- August 3, 2026
- Term ID
- EKS-HUM-060