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The Ventilation Rates Calculator helps HVAC engineers determine required outdoor air ventilation rates according to ASHRAE Standard 62.1. Calculate minimum outdoor air requirements based on occupancy and floor area for different space types.
Proper ventilation ensures acceptable indoor air quality by diluting indoor contaminants and providing fresh air for occupants. ASHRAE 62.1 specifies minimum ventilation rates that combine per-person and per-area components.
Enter floor area, occupant count, and space type to calculate required outdoor air in CFM. The calculator uses ASHRAE 62.1 ventilation rate tables for offices, classrooms, retail, restaurants, and fitness facilities, helping ensure code-compliant ventilation system design.
Features
Everything you need
- ASHRAE 62.1 ventilation rate calculations
- Per-person and per-area components
- Multiple space type support
- Total outdoor air determination
- Air changes per hour calculation
- Code compliance verification
- Imperial and metric units
How it works
Simple workflow
- 1Enter floor area and occupant count
- 2Select space type per ASHRAE 62.1
- 3Review per-person and per-area components
- 4See total required outdoor air in CFM
- 5View air changes per hour
Use cases
Built for real-world scenarios
HVAC design
Determine outdoor air requirements for HVAC system design and equipment sizing.
Code compliance
Verify ventilation designs meet ASHRAE 62.1 minimum requirements for different occupancies.
Indoor air quality
Ensure adequate ventilation for acceptable indoor air quality and occupant health.
Energy efficiency
Balance ventilation requirements with energy consumption in HVAC system design.
FAQ
Frequently asked questions
ASHRAE Standard 62.1 specifies minimum ventilation rates for acceptable indoor air quality. It's the basis for most building codes and requires both per-person and per-area outdoor air components.
Ventilation Rate = (Occupants × Rate per Person) + (Area × Rate per Area). For offices: 5 CFM per person + 0.06 CFM per SF. The calculator handles this automatically.
ASHRAE 62.1 rates: Offices 5 CFM/person + 0.06 CFM/SF, Classrooms 10 CFM/person + 0.12 CFM/SF, Restaurants 7.5 CFM/person + 0.18 CFM/SF. Rates vary by space type.
Minimum rates are required by code for health. However, demand-controlled ventilation (DCV) can reduce rates when spaces are under-occupied. Energy recovery ventilation (ERV) can reduce energy impact.
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