What ventilation rates does ASHRAE 62.1 prescribe?

ASHRAE 62.1-2022 calculates minimum outdoor air using the Ventilation Rate Procedure: V_oz = (Rp × Pz) + (Ra × Az), where Rp is the people outdoor air rate (CFM/person, e.g., 5 CFM/person for offices), Pz is zone population, Ra is the area outdoor air rate (CFM/ft², e.g., 0.06 CFM/ft² for offices), and Az is the zone floor area. The standard also specifies air distribution effectiveness (Ez) values that range from 0.5 to 1.2 depending on supply/return configuration and ceiling height, with ceiling-supplied cool air at 1.0. For VAV multiple-zone systems, the system-level outdoor air intake is calculated using Appendix A equations that account for zone air distribution effectiveness and the critical zone requiring the highest fraction of outdoor air.