airtightness

Nowadays the improvement of building airtightness is an essential condition to achieve high energy performance of buildings. Therefore, there is a need to precisely describe and quantify buildings infiltrations. 

Since the turn of the century, alarming data produced by the Indoor Air Quality Observatory (OQAI) have led to changes in French legislation, including, most notably, the introduction of compulsory labelling for construction products (decree no. 2011-321 of 23 March 2011).

In a sealed building with tight facades, conditions for a good indoor air quality and comfortable conditions must be guaranteed all the time especially for employees. This paper deals with the case of a specific retrofitted building without any openings that immediately shows many difficulties to maintain good indoor air quality in some parts of the occupied volume. An assessment of ductwork and HVAC system performance was first realized, conducted by the SNIA (National Airport Engineering Service).

The air infiltration of a building, which fundamentally depends on its airtightness, can be a significant contributor to its heat loss.  It can also be affected by other factors such as external terrain, leakage distribution, sheltering factor and environmental conditions. The infiltration rate of a detached UK house was monitored for 2 months in early 2018 using constant concentration and decay tracer gas methods under various temperature and wind conditions.

One of the main factors influencing building airtightness is the construction typology. As building environmental performance requirements raise so does the prevalence of less conventional envelope construction systems as modular structural insulated panels (SIPs) buildings.  

Substantial energy is used to condition the air that enters California homes through leaks in the building envelope and ductwork - typically about a third of all heating and cooling. Reducing this through air sealing is essential to California achieving zero energy homes. However, this outdoor air also dilutes pollutants emitted inside homes and contributes to a healthy indoor environment and acceptable indoor air quality (IAQ). To address this IAQ issue, California’s Title 24 Building Standards have required mechanical ventilation in new homes since 2008.