Commercial codes set minimum outdoor air by occupancy type, combining a per-person rate for people-related pollutants and a per-area rate for building-related ones; a typical office works out to about 5 cfm per person plus 0.06 cfm per square foot. Outdoor air is often the biggest single part of a building's cooling and dehumidification load, which is why it is measured, verified and controlled.
Ventilation rate for that classroom works out to 380 cfm of outside air, the unit's damper is barely cracked.
Also heard as
- outdoor air rate
- outside air rate
- OA rate
Related terms
DCV
Demand-controlled ventilation: adjusting outdoor air in real time to match how many people are actually in a space.
IAQ
Indoor air quality: how clean and healthy indoor air is, judged by contaminants, ventilation, humidity and comfort.
Economizer
Dampers and controls that bring in cool outdoor air for free cooling instead of running compressors.
Humidity ratio
The weight of water vapor per weight of dry air, usually given in grains per pound.
ERV
Energy recovery ventilator: a unit that swaps heat and moisture between outgoing exhaust air and incoming fresh air.