English

Air infiltration contributes to a heat loss typically representing up to one third of the heating demand of a building. The building airtightness, also quantified as air leakage, is the fundamental building property that impacts infiltration. The steady (de)pressurization method (blower door) is the widely accepted standard process for measuring building air leakage. However, this method requires the enclosure to be pressurised to a typical range of 10-60 Pa, which is not physically representative of the pressures experienced by buildings under natural conditions.

The air renovation of a building should be controlled in order to ensure a proper level of indoor air quality while minimize heat losses. It is a crucial point for the future energy efficiency goals. However, air infiltration rate in buildings is a complex parameter which is influenced by several boundary conditions. Although a detailed dynamic analysis could be used to properly characterize the phenomenon, estimated values can be obtained from experimental methods, as Blower Door test and gas concentration-based approaches.

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. 

Ventilation is critical in interpreting indoor air quality (IAQ), yet few IAQ assessments report ventilation rates; even when they do, the measurement method is often not fully described. Most ventilation assessments use a tracer gas test (TGT) to measure total air change rate. In a TGT, the indoor air is marked with an easily identifiable gas (tracer) so that the air exchange rate can be inferred by monitoring the tracer’s injection rate and concentration.

In France, the control of ventilation system at commissioning is mandatory in the context of the Effinergie + label and the measurement of airflows in residential houses is mandatory since 2017 in this label. The Promevent project (2013-2016) was aiming at improving the reliability of those controls. Guidelines have been issued for visual inspection of system, airflow measurements at air terminal devices (ATD) and ductwork airtightness measurements.  

The work reported in this paper extends previous work on the feasibility to characterise air leakage and mechanical ventilation avoiding intrusiveness of traditional measurement techniques. The feasibility to obtain the air renovation rate itself, as well as the possibilities to express it as function of other variables (such as wind speed, atmospheric pressure, etc.), are studied. Tracer gas measurements based on N2O have been used as reference.

The steady pressurisation method measures the building leakage in a range of high pressures, typically 10-60 Pa. It is implemented by creating a steady pressure difference across the building envelope and measuring the corresponding airflow exchange rate between the indoor and outdoor simultaneously. This method has been widely used and accepted as the standard test for demonstrating building air-tightness compliance. Conversely, the novel pulse technique, has been developed to measure the building air leakage at low pressures typically in the range of 1-10 Pa.

The air tightness of eight apartment buildings containing six to eleven units each on three or four floors has been tested with and without guard-zone pressure, i.e. with and without consideration of internal leakages. The layouts of these buildings varied: two of them had no central stairwell, in two other buildings, only some of the apartments were connected to the central stairwell, and the third type had all apartments connected to a central stairwell.   During these tests, two to eight BlowerDoor systems were used simultaneously to create guard-zone pressure conditions.  

Conventional building management systems are costly to install in existing buildings. Building services fail, which results in a cascade of incorrect responses, or occupants and administrators misuse systems. A possible way to reduce the installations costs is to use wireless sensor networks (WSN) to monitor and control building services.