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AHU Airflow Calculator
Calculate the required airflow for an Air Handling Unit (AHU) based on room volume and the required air changes per hour (ACH). Get results in m³/h, L/s, and CFM.
How to Size an AHU
AHU airflow is calculated as: Airflow (m³/h) = Room Volume (m³) × Air Changes per Hour (ACH). The required ACH depends on the space type and ventilation standard.
Offices typically need 3–6 ACH, while laboratories and healthcare spaces may need 10–15 ACH. Always check CIBSE Guide B and Building Regulations for specific requirements.
Frequently Asked Questions
How many ACH does an office need?
Offices typically need 3–6 ACH for fresh air supply, with higher rates for meeting rooms and dense occupancy. CIBSE Guide B provides detailed recommendations.
What is the difference between supply and extract airflow?
Supply airflow delivers conditioned air to the space. Extract airflow removes stale air. They should be balanced, with slightly more supply than extract to maintain positive pressure.
AHU Airflow Calculator
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