This newsletter from the French “Observatoire des Bâtiments Basse Consommation” (Observatoire BBC) gives information on the airtightness of new buildings, based on a comparison between the buildings that have got the “BBC Effinergie” label and buildings that did not get this label. [Since 2007, the BBC Effinergie label requires a measurement of the building airtightness on the construction site]. The mean airtightness of labellised buildings is 0.44 m3/h.m2 at 4 Pa for single family houses and 0.62 m3/h.m2 at 4 Pa for dwellings. The sample size is about 24,000 dwellings and 840 non-residential buildings.
This newsletter also mentions why the more recent Effinergie+ and BEPOS-Effinergie labels (operational since 2013) include requirements on ductwork airtightness measurement and checks on the ventilation system installation.