Air Changes Per Hour Calculator
Calculate Air Changes Per Hour (ACH)
About Air Changes Per Hour
Air Changes Per Hour (ACH) measures how many times the air in a room is completely replaced per hour.
Formula:
ACH = (CFM × 60) / Room Volume
Where:
- ACH = Air Changes Per Hour
- CFM = Cubic Feet per Minute
- Room Volume = Length × Width × Height
Recommended ACH Values:
• Living Room: 4-6 ACH
• Bedroom: 4-6 ACH
• Kitchen: 6-8 ACH
• Bathroom: 6-8 ACH
• Office: 6-8 ACH
Applications:
• HVAC system sizing
• Ventilation requirements
• Indoor air quality
• Energy efficiency planning
Proper air changes ensure good indoor air quality, comfort, and energy efficiency. Too few changes can lead to stale air, while too many can waste energy.