INFILTRATION

 
An empirical relation is used to calculate the infiltration rates.
   
The relation is a function of indoor and outdoor temperature difference and a constant. `
   
The constant depends on the tightness of the building:
  Tight building
  Standard building
  Leaky building
  Very leaky building
   
Reference:
PG Rousseau, EH Mathews, A new integrated design tool for naturally ventilated buildings, Energy and Buildings, 23, pp. 231-236, 1996.