airtightness

Infiltration is an uncontrolled contribution to ventilation in a building and can contribute significantly to the total ventilation rate, particularly in older, leaky, dwellings which can rely on infiltration to provide adequate indoor air quality. However, as explored in this paper, using a whole house airtightness metric to characterise ventilation rates can fail to identify low ventilation rates in specific rooms. 

Due to the wind induced pressure, different results may be obtained if the inside-outside pressure difference is measured across different locations on the building envelope, i.e. if the external pressure tap of a differential pressure sensor measuring this pressure difference is placed in different positions. Therefore, the position of the external pressure tap may influence an airtightness test result as well.

The airtightness of new buildings has significantly improved in the last two decades thanks to building energy performance regulations. However, until now, low knowledge is available about the evolution of buildings’ envelope airtightness. This work deals with the durability of buildings airtightness, and focuses on ways to better characterize it.

Wood is a hygroscopic material, it has the ability to adsorb or desorb water in response to the ambient relative humidity. Thus, the ambient air will affect the moisture content of the wood, and in turn, the dimension of the wood. If the wood itself is part of the air barrier in a construction, the shrinking and expansion can create gaps in the construction, for example in the window sill. In case of an air barrier consisting of a foil, the joints in the foil can be clamped by wooden joists, or the foil can be taped to wooden part.

Building airtightness requirements are becoming more and more common in Europe (Leprince, Carrié, & Kapsalaki, 2017). However, airtight buildings require an efficient ventilation system to ensure good indoor air quality. In France, the inspection of ventilation system (Jobert, 2012) has revealed many noncompliance. They are mainly due to bad conception, poor implementation, and lack of maintenance. This often leads to reduced ventilation flowrates and poor indoor air quality. Leaky ductwork is one of the reasons for this noncompliance.

In this paper a new methodology is presented to determine airtightness of buildings. The common method for airtightness testing is through fan pressurization with a blower door test. The new methodology also uses fan pressurization. Instead of an external fan, it uses the building fan system to pressurize the building.  

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).