Recent Developments in Building Diagnosis Techniques

Abstract

Infrared thermography (IRT) is a non-destructive evaluation technique that is used to visualize construction deficiencies, e.g. thermal bridges. In combination with a pressurization fan, IRT is also used to detect air leakages. The surface temperature change caused by the leakage air can be monitored by taking multiple IR images. Is it possible to assess the severity or quantify the flow of air leakages with this method? In order to link infrared images to the magnitude of air leakage flow, all influencing factors on the change in the surface temperature were examined in simulation models, laboratory and in situ measurements. The research showed that the visibility of an air leak is dependent on the position of other surfaces nearby. Consequently, the amount of air leakage flow cannot be related to the surface temperature change viewed on multiple IR images. Next to visibility issues, the change in surface temperature is proven to be smaller at large air leakage spots. This is due to the constant influence of the leakage air on the surface temperatures. Thermography is a sufficient technique for the visualization of air leakages that cause a clear surface temperature pattern under a pressure difference. However, it is not possible to derive the quantity of the air leakage flow.