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AHU ENGINEERING TOOL
AHU Face Area Calculator
Calculate gross AHU face area from airflow and target face velocity, or check face velocity from a known gross area.
Optional rectangular face helper
5.98 ft²Face velocity: 2.5 m/s (492.1 fpm)
Gross face area only. This calculator uses Q = A × V. It does not apply coil free-area, casing blockage, filter/media free-area, bypass allowance, fin geometry, or manufacturer-specific selection limits.
Engineering Method & Assumptions
Gross face area A = Q ÷ V, where Q is volumetric airflow and V is average face velocity normal to the selected face. The reverse check uses V = Q ÷ A. The optional rectangular helper divides gross face area by one known face dimension to obtain the other.
Engineering Scope
- Uses the continuity relationship Q = A × V.
- Area is gross geometric face area normal to airflow.
- No automatic allowance is made for coil tubes/fins, filters, casing members, dampers, bypass, free-area ratio or manufacturer-specific selection limits.
- Choose the target face velocity from the applicable component/manufacturer design criteria for the actual AHU section.
WHEN TO USE THIS TOOL
Useful during airside & ventilation work.
- Quick-check airflow, velocity, room-air-change or ventilation relationships during design reviews.
- Compare alternate design conditions before moving into detailed equipment or duct selection.
- Use as a transparent check alongside project criteria, applicable standards and manufacturer data.