The air we breathe is only one? Actually it might surprise you know how many types of air-exist.
We speak mainly of buildings in which an air conditioning system is used. The EN 10339 before and after the EN 13779:2007 (Ventilation for non-residential buildings – Performance requirements for ventilation and room-conditioning systems), diversify the air in the following way:
1) Outdoor Air (ODA): air entering the system or opening from outdoors before any air treatment;
2) Supply air: airflow entering the treated room, or air entering the system after any treatment;
3) Indoor Air: air in the treated room or zone;
4) Transferred air: indoor air which passes from the treated room to another treated room;
5) Extract air: the airflow leaving the treated room; (altro…)