Assessing the performance of three experimental methods to investigate air path inside wall assemblies

• Published in: Building and environment Vol. 264; p. 111937
• Main Authors: Hurel, Nolwenn, Woloszyn, Monika, Pailha, Mickaël, Moujalled, Bassam
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2024; Elsevier
• Subjects: Air leakage path; Civil Engineering; Construction durable; Engineering Sciences; Experimental methods; Fluorescein tracer; Heat transfer; Humidity transfer; Experimental methods; Air leakage path; Humidity transfer; Fluorescein tracer; Heat transfer
• ISSN: 0360-1323
• DOI: 10.1016/j.buildenv.2024.111937

Air leakages in buildings’ envelopes can lead to an over-consumption of energy and to additional issues such as moisture damage and poor indoor environment. The leakage air flow rate is usually assessed at the building scale using a pressurization test and leakage locations are commonly detected by infrared thermography or smoke. However, little is known about the air paths within wall assemblies, despite the need for detailed experimental data to validate numerical models for the coupled heat, moisture and pollutants transfers. One of the reasons is the difficulty to find adapted and robust experimental methods.
In this paper, three experimental laboratory approaches are tested on simple light-wall assembly configurations: the implementation of three-dimensional grids of thermocouples and relative humidity sensors within the wall, and the use of a micro-particle tracer. The results are compared with each other as well as with numerical simulations.
It was found that thermocouple grid has limited intrusiveness, good accuracy and response time but results are subject to flow fluctuations. Moreover, heat capacity and conductive transfer within materials complicate the correlation between heat and air transfers. Humidity sensors grid avoids the latter issue but is intrusive, overestimating air dispersion. The micro-particle tracer has the advantage of being non-intrusive and less impacted by flow fluctuations but its ability to track the air flow is strongly linked with the insulation filtration properties and the flow velocity. Overall this method seems to provide the best results but it is also the most complex and time-consuming one.
•Comparison of 3 experimental approaches to study air leakage paths inside walls.•Thermocouples have limited intrusiveness, good accuracy and response time.•The link between temperature mapping and velocity fields is not straightforward.•Humidity sensors are strongly intrusive, overestimating the air dispersion.•Best results obtained with fluorescein, but it is the most complex method.