Hygrothermal component simulation

Climate data and climate models

© Fraunhofer IBP

Hygrothermal behavior of typical components using the new reference year (red line) as compared to multi-year measurements at different locations within the observed climate region.

As part of sustainable environmental and climate protection and the responsible use of increasingly scarce energy resources, the need to reduce CO2 emissions makes further optimization of energy consumption in buildings inevitable.

In the climate of Central Europe, it’s especially important to improve building envelope insulation and achieve targeted ventilation – without risking uncontrolled shortcuts. Moisture load rises indoors when air exchange infiltration is lowered and, under unfavorable conditions, may result in increased surface moisture with mold growth. Planning or execution errors may cause moisture condensation inside the structure. Conversely, the rising thermal conductivity of damp materials may cause unwanted heat loss – a problem that can occur even without structural defects, for example, in roof constructions (e.g. through the migration of trapped moisture) and in retrofitted insulation from the inside.

On exterior surfaces, the insulated components’ lower temperatures result in longer condensation periods and therefore a greater risk of microbial growth. The still-common practice of combatting this growth with biocides must be assessed as critical, for example from the environmental perspective, because these substances accumulate in the soil and wastewater. In the European Union’s new hazardous substances regulations, their application has been limited still further.

Due to the risks mentioned above, careful planning of restorative measures that incorporate moisture protection takes on increased importance. The results of state-of-the-art simulation techniques have proven to be very reliable. Provided the required input parameters are available with sufficient accuracy, it is possible to predict relatively accurately how a structure or space’s temperature and humidity conditions will change after an energy-saving renovation.

When it comes to outdoor climate, the test reference years of the German National Meteorological Service (DWD) are typically used. These present the average climate of a region in regards to thermal aspects. Unfortunately, this depicts none of the critical burdens from a hygrothermal perspective. Local differences due to elevation, a building’s proximity to a forest or lake, or its location in the center of town – for the most part, these are disregarded in such an analysis, even though in many cases this information would make a crucial difference. Other aspects that cannot be sufficiently differentiated are building-specific characteristics, such as exposure to driving rain, the impact of ventilated façades or coverings, and the like. Climate conditions inside the building, especially in buildings used only temporarily or in unheated utility rooms and garages, are largely unknown.

The overall 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. The findings are intended to achieve a further reduction in construction and operating costs (energy savings) while keeping the building envelope reliable and free of damage.

This research project is funded by the German Federal Ministry of Economics and Technology (BMWi) as part of the Research for Energy-optimized Construction EnOB program

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Dr. Daniel Zirkelbach

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

Phone +49 8024 643-229

Fax +49 8024 643-366