Louver Free Area vs Face Area
Louvers have free area less than face area. Using face area for airflow causes undersizing.
What You Might Be Looking At
wall louver with horizontal blades, sizing for outdoor air intake
Apprentice words: louver size, louver opening, outside air grille, wall louver
Trade terms: louver free area, face area, free area ratio, louver performance
Check First
What Not To Do
Don't size by face area alone. Don't ignore free area ratio. Don't assume all louvers have same free area percentage.
What can go wrong: Undersized louver, excessive face velocity and noise, water infiltration, pressure drop, underperformance
Better Foreman Question
What's free area ratio for this louver? Size for specific face velocity to avoid noise and water penetration?
Verify With
Reference type: manufacturer data, ASHRAE
Source to verify: Louver manufacturer catalog (Greenheck, Ruskin), ASHRAE 62.1
Safe wording: Louver performance varies by blade type, depth, and manufacturer. Free area ratios typically 35-55%.