French database of building airtightness, statistical analyses of about 215,000 measurements: impacts of buildings characteristics and seasonal variations

The French database of building airtightness has been fed by measurement performed by qualified testers since 2006. In 2015 and 2016, the database was enriched by 63,409 and 65,958 measurements respectively, which is 74% more than in 2014, making the total number of measurements about 215,000. However, residential buildings (multi-family and single dwellings) account for almost all of measurements, only 4% of tests are performed in non-residential buildings. Indeed, since 2013 the French EP-regulation requires a limit for airtightness level for all new dwellings. The justification of the building airtightness level shall be done either by an airtightness test or by the application of a certified quality management approach. 
In the first part, this paper summarizes the recent results of the database regarding buildings’ characteristics (building area, main material, ventilation system, insulation...). 
The second part proposes first results regarding the evolution of air permeability. In single dwellings, the air permeability at 4 Pa (per unit of envelope area) slightly decreases from year to year with a mean value around 0.41 m3.h-1.m-2 in 2015. In multi-family buildings, the yearly mean air permeability fluctuates between 0.60 and 0.65 m3.h-1.m-2. In non-residential buildings, it fluctuates around 1 m3.h-1.m-2. However non-residential buildings cover a wide variety of buildings. A special focus is made on non-residential buildings depending on the use of the building and its size.  
The last part of this paper deals with the impact of the seasonal variations on the measured air permeability in single dwellings depending on climatic zones and buildings construction materials (wood, concrete and brick constructions). An impact of seasonal variations on air permeability is only observed in the case of wood constructions, with slightly higher values during summer in the south of France in particular.