n50 is a number used to quantify building airtightness. It gives the air change rate occurring as a result of air leakage through the building envelope when an air pressure difference of 50 Pa exists between inside and outside. This air change rate is the leakage volume airflow rate in m3/h measured at 50 Pa pressure difference divided by the buildings’ internal volume. It is expressed in h-1.

Posted in: Building Airtightness