Moisture load and airflow
Ventilation Air
通风空气
Ventilation air is the outdoor air intentionally introduced to a space to meet a defined ventilation requirement.
- Aliases
- ventilation outdoor air
QUANTITY, SYMBOL AND UNIT
Quantity / objectVentilation air
UnitNot applicable
Definition
Ventilation air is the outdoor air intentionally introduced to a space to meet a defined ventilation requirement.
Its flow is only one part of the air balance. The supply stream may also include recirculated or transfer air, while uncontrolled leakage is counted separately as infiltration. Ventilation air can add or remove moisture depending on its state relative to the controlled space.
Relations and distinctions
Ventilation air and supply air
Ventilation air is the outdoor-air portion required for ventilation; supply air is the full stream delivered to the space and may contain several air sources.
Ventilation and infiltration
Ventilation air is intentionally admitted and controlled. Infiltration enters through unintended openings under pressure differences.
Engineering meaning
- Include the design ventilation flow and its coincident temperature and humidity in the moisture-load balance.
- Confirm whether ventilation air is treated before mixing, after mixing or by separate equipment.
Common misconceptions
MisconceptionThe total supply-air flow is always the ventilation-air flow.
Accurate explanationOnly the stated outdoor-air portion is ventilation air; the remaining supply may be recirculated or transferred air.
Application boundaries
- The glossary definition does not set a health, occupancy or code ventilation rate.
- Annual-average weather data cannot replace coincident design or operating conditions for moisture-load checks.
Supporting sources
-
ASHRAE / SRC-ASHRAE-TERMINOLOGY-VENTILATION
ASHRAE Terminology: Ventilation Air and Supply Air ↗
Live terminology database / Entries: ventilation air, ventilation, outdoor air and supply air
Supports: Ventilation air is outdoor air required for controlling contaminant levels; Ventilation is intentional supply or removal of air for environmental control; Ventilation air is distinct from the total supply-air stream
Maintenance record
Ventilation 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-052