6 years of envelope airtightness measurements performed by French certified operators: analyses of about 65,000 tests

Since 2000, the French EP-calculations have been considering thermal losses due to building envelope airtightness. The last two regulations (RT2000 and RT2005) had included a default value for airtightness and the possibility to use a better-than-default value with a mandatory justification of this value, especially for voluntary approaches such as the BBC-Effinergie label. In 2013, strengthening the airtightness has become a requirement of the current EP-regulation (RT2012). It has implemented a limit value for airtightness for all new dwellings, and the mandatory justification of the building airtightness level through either an airtightness measurement or the application of a certified quality management approach. Therefore, there are more and more measurements of building envelope airtightness performed in a regulatory context.
In order to assess the quality of those measurements, the French Ministry for Ecology has implemented a process to certify the measurers. The first step of the process involves a qualifying State-approved training, a training exam, and the justification of a sufficient testing experience. Then, every tester is required to fill in a standard form every year. This form describes, for each measured building, various construction characteristics and airtightness measurement results. Since 2009, Cerema has been gathering the forms filled in by all qualified measurers. In 2015, those forms amount to about 65,000 measurements performed on dwellings and non-residential buildings in France.
This paper presents an analysis of this database. First, it proposes an overview of the measured buildings characteristics, including the main structural material and the use of the buildings. The second part of this paper presents first analyses on envelope airtightness. It describes the location of the leaks from criteria established in 2012. It also presents the evolution of the measured airtightness depending on various parameters such as the date of construction and the volume of the buildings. It also provides hints to evaluate the bias induced by thermal conditions through an evaluation of the impact of the season of measurement on the measured airtightness. The last part of this paper gives some feedback about the consequences of requiring a limit value: firstly, on the airtightness of buildings (both those subject to the requirement and those that are not), and secondly, on the practices of measurers.
In conclusion, this paper includes guidelines for using those data for different purposes, such as improving the control of certified measurers and reinforcing airtightness requirements for the next regulation.