Thermal Parameters and climate simulation in the laboratory

Test station for testing window air- and water-tightness.
© Photo Fraunhofer IBP
Thermal bridge calculation for an aluminum façade structure.
© Photo Fraunhofer IBP
Triple-chamber climate simulator for thermal (-30°C to 80°C) and humidity (5% to 95% RH) testing.
© Photo Fraunhofer IBP

Originally located exclusively in Holzkirchen, Germany, in May 2008 the department grew through the addition of the Stuttgart group on “thermal parameters and climate simulation.” This way, now all of the material parameters required for hygrothermal simulation can be determined within the department. Conversely, the steady state thermal testing methods in place in Stuttgart are supplemented by transient procedures introduced from Holzkirchen. Moreover, the departmental emphasis to date - on opaque building shells - is now supplemented through addition of transparent building components through certified test facilities in Stuttgart.

Another benefit of the expansion is the linkage between computational and laboratory climate simulation. Hygrothermal simulations help calculate maximum thermal and moisture-related loads for building components under practical conditions; these loads provide a basis for accelerated weathering experiments in the laboratory. Conversely, the leakage rates measured in laboratory climate simulation due to manufacturing-related imperfections in the building components tested can serve as inputs for hygrothermal simulation calculations. This way, manufacturing quality can be factored into computational predictions of the behavior of building structures as a function of temperature and humidity conditions. These predictions provide the basis for estimations concerning the durability and the risk of damage or failure.

Thermal parameters – Climate simulation

The thermal research laboratory at the Stuttgart site is officially recognized by the German building technology institute DIBt as a test center in accordance with the federal state building code (Landesbauordnung) and construction products lists (Bauregellisten) and as a Notified Body (no. 1004) for windows, façades and insulation materials in accordance with the EU Construction Products Regulation. The laboratory also has flexible accreditation from Germany’s national accreditation body DAkkS (Deutsche Akkreditierungsstelle GmbH) in accordance with DIN EN ISO/ IEC 17025. Numerous parameters are used to determine the characteristics of building components and materials, including the following:

  • Thermal conductivity
  • Thermal resistance
  • U-value
  • Heat dissipation
  • Dimensional stability under the effects of heat
  • Compressive stress and tensile strength, adhesive strength
  • Freeze-thaw resistance
  • Moisture absorption via vapor diffusion in temperature gradient
  • Flow resistivity
  • Air permeability
  • Resistance to rainwater penetration
  • Resistance to wind load

Integral radiation-technology methods are also employed, including the following:

In addition, various solar simulation facilities are available to test building component surfaces of up to 8 m2 under radiation loads.



Controlling the weather

If only we could control the weather! While for most of us this remains pie in the sky, it’s an everyday occurrence for engineer Andreas Zegowitz and his team from the Thermal Parameters and Laboratory Climate Simulation group.  



Localized cooling

Averaged out over a year, temperatures in greater urban areas, cities and megacities all across the world are now one to two Kelvin higher than in the surrounding rural areas. Depending on the size of the settlement, the temperature difference can be as much as ten Kelvin, which has given rise to the term “urban heat island.”

A novel paving stone concept should now help to reduce this effect.



Optimal ventilation with Climawin

A project funded by the European Union’s Seventh Framework Programme (FP7) and bringing together partners in Denmark, Ireland, Portugal and Germany, has come up with a novel window system. Equipped with electronically controlled ventilation flaps, it can pre-warm the air you need to ventilate your rooms.



Blinds between window panes.

Usability tests on blinds sandwiched between vacuum-glazed panes are necessary to guarantee that such systems last long enough once installed. Frequent cases of damage show that even systems that have already been tested are often faulty.



Window/wall connections

Research on the hygrothermal behavior of window/wall connections was carried out in the dual-chamber climate simulator using two types of PU foam adhesive, without films for additional sealing. For the comparison, commercially available joint filler with caulking as well as with interior and exterior films was tested under the same climactic conditions.



Cleanroom ceilings put to the test

Our growing dependence on electronic equipment to help us, both in industry and in daily life, means more and more cleanrooms are needed by companies such as microchip manufacturers. Cleanroom air exchange requirements are particularly stringent, and as a result it is vital that their construction systems meet exacting air permeability criteria.  

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Andreas Zegowitz

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Andreas Zegowitz

Fraunhofer Institute for Building Physics IBP
Nobelstr. 12
70569  Stuttgart, Germany

Phone +49 711 970-3333

Fax +49 711 970-3340