Infiltration is caused by wind, negative pressurization of the building, and by air buoyancy forces known commonly as the stack effect.
(CFM x 60)/volume Infiltration in finished structures can often be measured directly by using tracer-gas leak testing.
ASHRAE Standard 62.2 was adopted in 2004; it clarifies the ventilation air requirements for low-rise residences.
[2] This is typically accomplished with heat recovery ventilation or exhaust fans running constantly or periodically.
Typically, infiltration is minimized to reduce dust, to increase thermal comfort, and to decrease energy consumption.