Outdoor Air Mix
Mixed dry-bulb and humidity ratio from RA/OA states and OA fraction.
Example
You enter
- Return air temp (°F) 75
- Return RH (%) 50
- Outdoor air temp (°F) 95
- Outdoor RH (%) 60
- OA fraction (0-1) 0.2
You get
- Mixed dry-bulb 79 F
- Oa fraction 0.2
Details, formula, and sources
Mixed-air dry bulb T_mix = (CFM_OA × T_OA + CFM_RA × T_RA) / (CFM_OA + CFM_RA). Outdoor-air ratio against ASHRAE 62.1 ventilation rates by occupancy.
ASHRAE 62.1-2022 (Ventilation for Acceptable Indoor Air Quality).
Free read-only access to ASHRAE standards at ashrae.org (Technical Resources, read-only standards).
Estimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.
Field names used by the API: return_T_F, return_RH_percent, outdoor_T_F, outdoor_RH_percent, oa_fraction, mixed_T_F
- Default occupancy ventilation rate user-supplied per ASHRAE 62.1-2022 Table 6-1ASHRAE 62.1-2022