Thermography uses the fact that all objects emit thermal radiation. With the help of the thermal camera, this - normally invisible - heat radiation is recorded and displayed as a visible image. By displaying the temperature distribution over an area, it is possible to determine the area of influence of thermal bridges, i.e. zones of increased heat loss, and leaks.

During their studies, students learn the correct use of thermography as well as its application limits and the problems that can sometimes occur.

 

Thermography

Testing the airtightness of a building with the Blower-Door

Within the framework of the building physics laboratory experiments, students are familiarized with the use of the blower door. The quality of the airtightness of the building is determined and documented by the blower door measurement. In all buildings, but especially in wooden buildings, there are construction-related component joints and connections which can be regarded as potential leaks. Even masonry walls only become "airtight" when they are plastered without interruption. Window and door connections, chimneys, electrical and above all sanitary installations without permanent seals are an often underestimated source of leakage. These leakages increase the heating energy demand of a building and thus the heating costs.

Blower-Door measuring method

Determination of the thermal conductivity

Using a specially developed two-plate device and a commercially available single-plate device, students learn how to measure the thermal conductivity of building materials in the building physics laboratory practice. In addition, the experiments illustrate the differences between stationary and unsteady thermal conditions.

Determination of the thermal conductivity

The department of building physics has various measurement methods at its disposal with which air flows within double facade systems or in large rooms can be visualised and analysed.

Particle Image Velocimetry (PIV)

Particle Image Velocimetry is a method for non-invasive measurement of flow processes. Small particles in the form of helium-filled soap bubbles (bubble diameter approx. 1-2 mm) or oil mist (particle size in the um range) are mixed into the air. The individual particle movements are recorded with a high-resolution CCD camera. The particle or particle pattern movements of the particles are evaluated and vectorized via image processing.

 

Particle Tracking Velocimetry (PTV)

While Particle Image Velocimetry (PIV) is based on the pattern recognition of particles and their "migration" within several image sequences, the Particle Tracking Velocimetry (PTV) method offers the advantage of tracking individual particles over a longer period of time and a greater distance (over all spatial dimensions). In contrast to the PIV method described above, the tracking method uses balloons as particles instead of soap bubbles. These were also filled with a helium-air mixture in such a way that the weight of the balloon envelope was just lifted. Two synchronized, spatially offset standard cameras are sufficient for the 3D stereo tracking method.

Flow visualization