Review and analysis of existing diagnostic methods for characterizing air transfers in existing homes

Buildings energy renovation is a major priority in most European countries in order to achieve a fully decarbonized building stock by 2050. In France, 7 million homes are poorly insulated and 14% of French people feel cold in their homes. The government has thus implemented an ambitious plan to scale up energy-efficient renovations of buildings to achieve carbon neutrality by 2050 while also pursuing a social objective of combating energy precarity. 
More and more energy audits are being carried out, and the diagnostic method will be overhauled in 2024. These audits are often the only diagnostic work carried out prior to energy renovation, which must be done on a massive scale and quickly if the government's targets are to be met. Yet, existing homes feature a wide range of ventilation systems (non-existent, natural, mechanical) and levels of envelope air permeability. Overlooking these essential parameters in the energy renovation process, which are vital for ensuring good indoor air quality, could result in a proliferation of under-ventilated dwellings. 
Air change rate in dwellings have an impact on both their energy performance and indoor air quality, particularly through the air infiltration of dwellings and the ventilation airflow. Methods currently exist for characterizing and assessing these factors using in situ measurements. However, these methods are often time-consuming to perform, and there are constraints on their widespread use during housing renovations. The most commonly used methods to characterize building air permeability and natural airflow rate are the blower door and tracer gas, respectively. 
Recently, alternative methods for measuring building airtightness such as the Pulse method have been developed. This paper aims to investigate the existing measurement methods and devices for in-situ diagnostic of air change rate (air permeability of the envelope and natural ventilation airflow) in existing French and English dwellings. 
This paper presents a review of the various existing methods for measuring building air permeability and natural airflow rate, and analyses the advantages and disadvantages of their use in existing occupied dwellings based on the reliability of the measured parameters and practical constraints.