Moisture protection assessment and hygrothermal model development

© Photo Fraunhofer IBP

Although energy-saving initiatives have led to significant improvements in heat insulation and sealing off building interiors, these improvements are associated with an increased risk of moisture damage arising from higher indoor air humidity, which enhances the probability of condensate. Adding to this problem, there is less heat available overall to evaporate moisture accumulated in construction components, with the result that other moisture issues such as rainwater, condensation water from outside and trapped humidity pose a greater problem than in the past.

This makes a precise appraisal of hygrothermal conditions and targeted moisture control design more important than ever, accompanied by the search for new solutions and approaches. Most damage can be avoided by careful planning and implementation of moisture protection measures and by choosing the right materials. A traditional means of moisture protection assessment is the Glaser method. However, this method only takes into account condensation formed as a result of diffusion from the interior such as commonly occurs in winter – it cannot evaluate other important factors for many buildings, such as trapped moisture, driving rain and summer condensation.

Today’s hygrothermal simulation software is capable of delivering realistic calculations of all relevant hygrothermal storage and transport processes in components under real climatic conditions. As well as allowing comprehensive moisture control design, this also makes it possible to take the energy effects of moisture into account. Demand for the WUFI® software family first licensed by Fraunhofer IBP in 1995 is growing around the world. Intensive program maintenance ensures that new discoveries in building physics are swiftly implemented and that material and climate databases are continuously updated with new information. In collaboration with many international partners, new functions are being added to the programs all the time, including tools for evaluating leaks, damage mechanisms and ageing processes.

 

 

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Hygrothermal reference years

In most cases the simulations are based on climate data originally compiled for use when dimensioning heating and air conditioning systems. These data focus more on temperature than on humidity, and are therefore less suited to the hygrothermal analysis of building components.

 

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Climate data and climate models

The objective of this project is to create a robust and reliable base of climate data to be used with the building physics simulation techniques. These in turn promote energy-optimized construction and support climate-friendly renovation measures for existing buildings.

 

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Internal insulation with fiber insulation materials

From a building physics perspective, internal insulation is usually less desirable than external as far as thermal bridges (heat loss), condensation and drying potential are concerned. This makes careful planning and execution a prerequisite for anyone wanting to install internal insulation that is going to last.

 

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Reverse roof insulation

Reverse roof insulation does not employ additional seals to protect against the effects of weather. The outer layers for instance made of paving stones, gravel or substrates, also serve to store more moisture from precipitation, which means the area above the insulation usually experiences only short dry periods.

 

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Green roof oasis

Green or "living" roofs are no longer the preserve of the wealthy or the extravagant creations of modern architects looking to make their mark. Modern ecologists class them as settlement biotopes. They are stipulated in some land use plans as a counterbalance to paved surfaces – and in some parts of Germany they even attract public subsidies. As well as storing rainwater and improving the microclimate in cities, many green roofs are cultivated as rooftop gardens which provide an attractive contrast to surrounding buildings.

Contact us

Martin Krus

Contact Press / Media

Prof. Dr. Martin Krus

Fraunhofer Institute for Building Physics IBP
Fraunhoferstr. 10
83626  Valley, Germany

Phone +49 8024 643-258

Fax +49 8024 643-366

Daniel Zirkelbach

Contact Press / Media

Daniel Zirkelbach

Fraunhofer Institute for Building Physics IBP
Fraunhoferstr. 10
83626 Valley , Germany

Phone +49 8024 643-229

Fax +49 8024 643-366