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Grille / Diffuser Sizing
Size supply and extract grilles and diffusers by face and core velocity.
The Ensign ToolboxGrille / Diffuser SizingSize supply and extract grilles and diffusers by face and core velocity.
Airflow
L/s
Supply or extract flow through the terminal
Terminal face
mm
mm
%
Manufacturer core/gross area; typically 70–90%
Sizing target
m/s
Free-area (core) velocity — the verdict bands this, not face velocity. CIBSE/ASHRAE ~2–4 m/s occupied, lower for quiet rooms
Enter the airflow through the terminal (> 0)