Air Changes Calculator
Calculate the required ventilation airflow rate from room volume and air changes per hour.
Débit d'air requis
1,080 m^3/h
Required Airflow vs Room Length
Formule
## Air Changes per Hour (ACH) ACH defines how many times the entire room volume of air is replaced per hour. ### Formula **Airflow = Room Volume x ACH** Required ACH depends on the room function. Adequate ventilation controls temperature, humidity, odours, and airborne contaminants.
Exemple Résolu
A 10m x 6m x 3m room requiring 6 air changes per hour.
- 01Volume = 10 x 6 x 3 = 180 m^3
- 02Airflow = 180 x 6 = 1080 m^3/h
- 03Airflow = 1080 / 3.6 = 300 L/s
Questions Fréquentes
What ACH is required for different spaces?
Office: 4-6 ACH. Classroom: 6-8. Kitchen (commercial): 15-30. Workshop: 8-12. Hospital operating room: 15-25. Toilet/bathroom: 8-15. Warehouse: 2-4.
Is higher ACH always better?
Not necessarily. Excessive air changes waste energy by conditioning (heating/cooling) more air than needed. Balance indoor air quality needs against energy efficiency.
How does this relate to CO2 levels?
Ventilation removes CO2 exhaled by occupants. ASHRAE recommends keeping CO2 below 1000 ppm. The required outdoor air per person (typically 8-10 L/s/person) may give a different answer than ACH-based calculations.
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