Mold infestation is not a rare phenomenon. In Germany alone, some 10 percent of all structural damage to buildings is related to mold. If the building is not allowed to breathe or if the occupants do not air the rooms sufficiently, moisture can build up in the interior. This leads to excessive humidity, which in combination with cooler external walls – par example because of deficient thermal insulation – provides the ideal conditions for mold to thrive. Another problem is when people move into new buildings too soon after construction, as excessive residual moisture can also quickly lead to mold formation. Further common construction-related factors that can lead to mold are defects such as thermal bridges, faulty insulation work, water damage from defective pipes, and poorly positioned furniture that prevents air from circulating between the walls and the furniture. According to a survey conducted by Fraunhofer IBP scientists, some 84 million people in the European Union – including Iceland, Norway and Switzerland – live in damp homes. The consequences for their health can be serious. For example, asthma has long been very prevalent, affecting 7 percent of adults in Europe. “In the baseline study we carried out, we concentrated on the relationship between mold in interior spaces and its effects on the health of occupants,” explains Prof. Gunnar Grün, deputy director of Fraunhofer IBP and head of the Energy Efficiency and Indoor Climate department. “For instance, we quantified the risk for people living in homes with mold problems of developing a respiratory disease. Fundamentally, we are convinced that mold and mold prevention are an important topic for research and development into healthy living. The baseline survey we carried out offers additional proof of this.”
Excerpts from results and findings
Fraunhofer IBP’s baseline study compiled data from 170 scientific surveys. These were based primarily on observations and did not include experimental studies such as clinical trials. The majority (99) were empirical studies, while the remainder were case analyses (31) and cohort analyses (40). The evaluation for the meta-study shows a clear correlation between respiratory tract infections and damp, moldy interiors.
Prof. Grün and his colleagues were able to demonstrate that the probability of developing asthma is 40 percent higher when people live in a mold-infested home. When we apply this ratio to the number of Europeans who live in damp homes compared to those who live in homes without moisture problems, this gives us a figure of about 2,2 million people who suffer from asthma specifically because they live in a damp, moldy environment.
In order to combat this illness-causing problem of defective building stock, future renovation efforts must stress the importance of professional planning, design, and workmanship. If indoor climate and structural engineering conditions were improved during renovation work, the number of people affected by the problem could be reduced. If we take a conservative modernization rate of 2 percent per year as a baseline together with higher quality such that only 8 percent of renovated buildings are affected by moisture problems instead of 16 percent, by 2050 we would see around a 25-percent drop in the number of people experiencing these problems. In the case of asthma, this would result in approximately 550,000 fewer people developing the illness, with the associated reduction in costs for the public health system.
Approaches to tackling the problem
In addition to being unhygienic, the uncontrolled growth of mold inside homes is also a potential risk to the health of the people living there. By the time a patch of mold becomes visible, there is already an area of 20 square centimeters that requires urgent treatment. In various departments, Fraunhofer IBP carries out research into issues such as how to avoid and combat unwanted moisture in building components and develops solutions including balcony reinforcement anchors for reducing thermal bridges. Transient calculations of the coupled one- and two-dimensional heat and moisture transport in multi-layer components and buildings can be carried out in advance under natural climate conditions thanks to the WUFI® (a German acronym that stands for heat and moisture transiency) software family. This calculation method was developed at Fraunhofer IBP and validated on outdoor and laboratory data from all over the world. Among other things, it makes it possible to realistically calculate the transient hygrothermal behavior of components and buildings under natural climate conditions. In addition, the scientists create evaluation classes to grade the risk to health and test the environmental compatibility of algae and fungi biocides. Other building physics aspects that can be explored in order to prohibit the problem of damp homes and mold infestations include investigations into the drying behavior of components and the question as to whether individual fireplaces or stoves eliminate the risk of mold growing on the interior side of walls.