To reduce the CO2 footprint of buildings, renewable raw materials such as wood and natural fiber products are increasingly being used as building materials. Due to their biological origin, however, these materials may be susceptible to decay fungi under certain moisture and temperature conditions, particularly when exposure lasts long enough. For the design of durable assemblies, it is therefore essential to identify boundary conditions under which decay risk can be reliably avoided.
Traditional assessment methods are often based on steady-state limit values, such as a wood moisture content of 20% by mass for solid wood or 18% by mass for wood-based materials according to DIN 68800, as well as temperature-dependent limit curve according to WTA Guideline 6-8. While these approaches provide a high level of safety, they lead to conservative assessments. In addition, they do not account for the duration of moisture exposure. As a result, short-term exceedances of these limits may already be classified as “failure,” even when there is no actual decay risk.
WUFI® Decay closes this gap by considering not only temperature and moisture, but also the duration of exposure and material-specific decay resistance*. Based on the proven methodology of the WUFI® Bio mold growth prediction model, WUFI® Decay has been further developed for the assessment of decay fungi. It enables a more realistic assessment of decay risk based on transient hygrothermal simulations.
* Information on the decay resistance of wood-based materials and natural fiber insulation materials
While extensive knowledge is already available for solid wood regarding the critical conditions for wood decay, corresponding assessment criteria have so far been lacking for natural fiber insulation materials and wood-based products. Based on findings gathered from several research projects, new test methods were therefore developed to determine the material-specific decay resistance of these materials. The resulting characteristic values can be integrated into WUFI® Decay, making it possible to provide material-specific and realistic predictions of decay risk for natural fiber insulation materials and wood-based products.
Die Grundlagen des Modells und Validierung sind beschrieben in:
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