Onset of mould growth – the effect of climate variability and different geographic locations

This paper presents a study on how climate conditions at numerous locations in Sweden affect the risk of onset of mould on wood sheltered outdoors. The results indicate that the risk is clearly higher in the south compared to the north of Sweden. These differences are mainly explained by colder and dryer winter periods in the north which is unfavorable for development of mould. The results also show that the climate effect with respect to risk for mould growth has a significant variation between different years. Thus, the risk for unfavorable effects cannot be solely based on predictions for a so-called normal year without considering years with more extreme climate effects. Based on the results it is argued in favor of developing a quantitative method to assess the risk of mould growth using probabilistic methods and reliability analysis. Such a method should be simple enough for the general engineer to implement and serve as a valuable tool in order to avoid inappropriate design and potential health related problems.