How airtightness testing differs between Building Regs and Passive House – and why it matters so much

Using a smoke pen to detect leaks during airtightness testing

Building Regulations Part F wants to know how much air (in m3hr) passes through each metre square area of the fabric (m2). This is the Air Permeability (AP or m3.hr/m2) figure of the building. To get the AP figure, one calculates the volume of air in the property. Then one calculates the total external envelope … Read more