ASHRAE 62.1 Outdoor-Air Ventilation
Breathing-zone and zone outdoor airflow per ASHRAE 62.1 §6.2.2.1.
Example
You enter
- Rp (cfm per person) 5
- Ra (cfm per ft²) 0.06
- People (Pz) 25
- Floor area (ft²; Az) 2500
- Air-distribution effectiveness (E_z; default 1.0) 1
You get
- Vbz breathing-zone outdoor air (cfm) 275
- Voz zone outdoor airflow (cfm) 275
- Per-person (cfm/person) 11
Checked against published worked examples from: ASHRAE.
Details, formula, and sources
ScopeUser supplies Rp / Ra from the AHJ-adopted edition; Table 6-1 is not bundled.
Formula or tableVbz = Rp * Pz + Ra * Az. Voz = Vbz / E_z. Per-person and per-area ratios surface the design density.
Source and editionASHRAE 62.1-2022 §6.2.2.1 (single-zone breathing-zone procedure). AHJ-adopted edition governs.
Free accessashrae.org/technical-resources/standards-and-guidelines/read-only-versions-of-ashrae-standards for TOC.
What governsEstimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.
API field namesRp_cfm_per_person, Ra_cfm_per_ft2, people, floor_area_ft2, Ez, Vbz_cfm, Voz_cfm, cfm_per_person
- Rp / Ra user-supplied; placeholder presets for office / classroom / retail are starting points onlyASHRAE 62.1-2022 Table 6-1 (not reproduced)
- E_z default 1.0 (ceiling supply with ceiling return)ASHRAE 62.1-2022 Table 6-2
- E_z range 0.5 to 1.2 typicalASHRAE 62.1-2022 Table 6-2