Permeability of a material to air flow


The maximum depressurisation for a dynamically insulated building is normally limited to 10 Pa in order to avoid doors slamming shut or difficulty in opening doors.The function of the air control layer (Fig 1) in a dynamically insulated wall or ceiling is provide sufficient resistance to the air flow to achieve the required pressure drop at the design air flow rate. The air control layer requires to have a suitable air permeability and this is the key to making dynamic insulation work.

Related formulas


ΦThe permeability of the material to air flow (m2/h*Pa)
LThe thickness of material through which air flows (m)
V*The volume flow rate of air (m3/h)
AThe area of material through which air flows (m2)
ΔPThe pressure difference along the length L of material (Pa)