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Ventilation Rate Calculator (ASHRAE 62.1) | Engineering Database

Ventilation Rate Calculator (ASHRAE 62.1)

mechanical

Calculates required outdoor air ventilation rates per ASHRAE 62.1 Ventilation Rate Procedure. Looks up per-person (Rp) and per-area (Ra) rates by occupancy category and calculates total outdoor air CFM.

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Occupancy Category*

ASHRAE 62.1 occupancy category code for Rp and Ra lookup. Examples: 'office_general', 'classroom_k12', 'restaurant_dining', 'conference_room', 'hotel_guestroom', 'gym_fitness', 'retail_sales'. Must match a key in the ventilation-rates reference table.

Floor Area Ft2*

Gross floor area of the zone in square feet. Used for the area-based ventilation component (Ra * floor_area) and to estimate occupant count from default density if num_occupants is not provided. Gross floor area of the ventilation zone. Typical: 100-5000 ft² per zone.

Num Occupants

Actual or design number of occupants in the zone. If omitted, occupant count is estimated from floor_area_ft2 using the default occupant density for the occupancy category per ASHRAE 62.1 Table 6.2.2.1.

Zone Air Distribution Effectiveness

Zone air distribution effectiveness (Ez) per ASHRAE 62.1 Table 6.2.2.2. Typical: 1.0 for ceiling supply with ceiling return, 0.8 for floor supply with ceiling return (heating mode), 1.2 for displacement ventilation. If omitted, defaults to 1.0.

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Reference data

This calculator pulls live values from the following engineering reference tables in the database.

ashrae ventilation rates

About this calculator

Ventilation Rate Calculator (ASHRAE 62.1) is part of the Engineering Database calculator suite. Each tool runs deterministic calculations against authoritative reference data and code-compliant methods, so results are reproducible and traceable to source standards.

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