Project Structure
Welcome to ASHRAE 62.1 Calculator
Start by loading an existing project or create a new one
Project Information
Unit Configuration
Total number of occupants expected to be present simultaneously in all zones served by this system. Used to calculate Occupant Diversity Factor (D = Ps / ΣPz). Leave empty or 0 to use sum of zone populations (D = 1.0).
Occupant Diversity Factor (D): -
Zone Configuration
Space Configuration
Rp:
-
Ra:
-
Primary supply air delivered to this space
Exhaust air from this space (for air balancing)
Net Airflow = Supply - Exhaust. Positive = positive pressure, Negative = negative pressure, Zero = balanced (per ASHRAE 62.1 & IMC 2024)
Target net airflow as % of supply. Positive = positive pressure, Negative = negative pressure. Used to calculate required exhaust.
When checked, all supply air is exhausted (zero return air). Net airflow = 0 (balanced).
Return Air = Supply - Outdoor Air (per ASHRAE 62.1). Estimated based on space's share of zone outdoor air requirement.
Minimum exhaust required to achieve desired net airflow (negative pressurization)
Calculation Results
Building Pressurization & Air Balancing
Zone-by-Zone Air Balancing
Airflow Verification Report
| Unit | Zone | Space Name |
Occupancy Category |
Area (Az) (ft²) |
Design Occupancy (Pz) |
Zone OA Required (Vbz) (CFM) |
Zone OA Required (Voz) (CFM) |
Primary Supply (Vpz) (CFM) |
Zone Ratio (Zj) |
|---|
💡 Calculations update automatically