##  [Air Permeability](/index.php/air-permeability) 

  ##  [Air Permeability](https://engineering.quantumdictionary.io/air-permeability-0) 

  

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**Engineering & Applied Technologies Dictionary**

 







 

 

 

 



 

 

 

 

Definition

A quantitative measure of how easily air passes through a building envelope or component under a specified pressure difference, usually reported as volumetric flow per unit area at a reference pressure (e.g., m³·h⁻¹·m⁻² at 50 Pa) or as a whole‑building normalized leakage (m³·h⁻¹·m⁻² or n50). It characterizes uncontrolled leakage paths, not designed ventilation.