Ventilation & Airflow Calculator (ACH/CFM)
Calculate required Airflow (CFM) based on Room Volume and ASHRAE Air Changes Per Hour (ACH) standards. Essential for HVAC sizing and IAQ compliance.
About
Indoor Air Quality (IAQ) is not just about comfort; it is a health and safety mandate. Inadequate ventilation leads to "Sick Building Syndrome," accumulation of CO2, and viral spread. This tool calculates the required volumetric airflow in Cubic Feet per Minute (CFM) based on the Air Changes Per Hour (ACH) method, which is the industry standard for ensuring a room's air is completely replaced at a specific rate.
Different environments generally have drastically different requirements. A residential living room may only need 4-6 changes per hour, while a hospital operating room or a server farm might require 20-30 to manage heat load and contaminants. This calculator integrates standard ranges derived from ASHRAE 62.1 and medical facility guidelines, allowing contractors to size fans and ductwork with confidence.
Formulas
The relationship between Airflow (Q), Room Volume (V), and Air Changes Per Hour (N) is:
To determine the Volume from dimensions:
Reference Data
| Room Type | Recommended ACH | Notes |
|---|---|---|
| Residential Living | 4 - 6 | Standard comfort |
| Kitchen (Commercial) | 15 - 30 | Heat & smoke removal |
| Bathroom (Public) | 10 - 15 | Odor control |
| Office Space | 4 - 10 | CO2 management |
| Server Room | 20 - 50 | Critical heat dissipation |
| Garage (Enclosed) | 6 - 10 | Exhaust fumes (CO) |
| Laboratory | 6 - 15 | Fume hood dependencies |
| Classroom | 6 - 8 | Student density factor |
| Warehouses | 2 - 4 | Low occupancy |