Building biologist first looks at the floor structure

Floor identified as source of pollutants

Floor identified as source of pollutants

How to find pollutants in the house

When looking for the source of pollutants in the indoor air, Oliver Zenkel always focuses on the floor first. The building biologist draws on several years of experience and also provides a simple reason. Although walls have the larger surface portion at a dwelling, but floors are usually multi-layered developed and thus substantially more susceptible for pollutant entries into the ambient air. Zenkel views flooring as a system in which not only the individual material plays a role, but also the interaction of the components.
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Away with the wallpaper in case of mold on the wall

mold in bedroom cornerMold grew nearly overnight – Sylvia Bittner couldn’t believe her eyes when she moved the bed in the children’s room to one side. Within two weeks, a dark turf of mold had grown on the wallpaper from the base to a height of forty centimeters. Sylvia had only moved into the rented apartment on the second floor with her family in the summer. The realtor had told her nothing about a mold problem and the apartment had been freshly painted. In late November, mold growth came upon the residents out of the blue. Sylvia picked up the phone and reported the matter to the property manager. When after eight days there was still no remedy in sight, the worried mother of two asked the consumer advice center. The friendly lady on the phone advised her to record the damage with a camera and to put the property management in default in writing. The advicer recommended that the rent payment be made with reservations so that she could later assert claims for repayment. But Sylvia Bittner was not thinking about money at first – she was much more concerned about the health of her children.
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Severe cell phone radiation along boardwalk

Poorly designed antenna structure at Stockholm

Seven low-level mobile phone antennas are located along the shore road in the Skeppsbron district of Stockholm (Sweden). An international team of researchers led by Mikko Ahonen from Finland and Michael Carlberg from Sweden concluded in a study that the determination of the locations along the shore road serves as an example of a poorly designed antenna structure. A portable exposimeter was used to record electromagnetic radiation at various measurement points. The highest average field strength in one of the defined segments was 12.1 volts per meter (V/m), corresponding to a radiation density of 388 milliwatts per square meter (mW/m²). The peak value in the area studied was 31.5 V/m (2,648 mW/m²), reaching over 50 percent of the internationally accepted limit of 61 V/m at a frequency of 2,600 megahertz.
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Straw and clay get along well

Architect Florian Hoppe presents the straw bale building

Architect Florian Hoppe presents the straw bale building

Architect Florian Hoppe knows his way around both building materials– He developed a relationship with clay at a very early age in his father’s company. He learned masonry and plastering by working on several construction sites in Thuringia/Germany. Through a cooperation of different companies it was even possible to use local clay. In the course of his architectural studies, Hoppe became enthusiastic about straw bale construction. One idea in particular from the settler days in America did not let him go: he wanted to realize the load-bearing straw bale without wooden stud construction in Germany as well. After careful preparation and with the support of his family, he was able to move into his spacious straw house ten years ago.
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Residential toxins in old prefabricated house

prefabricated house real estate check

prefabricated house real estate check

Building biologists are regularly asked for advice

Prefabricated houses from the seventies are part of the fixed portfolio of real estate agents. Mostly, the offers are tempting for young families. The most important plus points are considered to be a prime location, a relatively large plot of land, a good room layout and, ultimately, a favorable price. Too often, homebuyers suppress the problem of pollutants in older prefabricated houses. Even fifty years after completion, certain groups of pollutants have not yet been aired out.
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Pay attention to the dew point

Mold experts use a dew point calculator

The focus is on room air temperature and relative humidity

Visible mold growth in the apartment always causes discomfort for those affected. After all, no one wants to have the unloved co-inhabitant in their neighborhood. To analyze the causes, it is essential to take a look at the physical relationships in the building. The focus is on room air temperature and relative humidity as well as on the surface temperatures of the surrounding surfaces. Mold always grows when it finds enough food and sufficient moisture in its environment. The fungus is not choosy about its “food”. A little house dust is enough, as it can be found in every apartment. In the most frequent cases of damage, condensed water vapor from the air in the room is responsible for the influx of moisture. Mold experts use the dew point calculator to determine cause and effect.
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Using the ACI value to assess the radioactivity of building materials

gamma rays in building materials

Gamma rays in building materials endanger health

The European Union (EU) has developed the Activity Concentration Index to assess radiation exposure

The large-scale installation of radioactive building materials indoors can endanger the health of the occupants. Granite, tuff or pumice are building materials with radioactive potential. However, sand, gravel, limestone and natural gypsum can also be radioactively contaminated under certain circumstances. The builder does not always know which rock is in a product. For example, a masonry block is offered under the brand name “Liapor”, without the buyer knowing that pumice rock is hidden behind it. The European Union has therefore developed the Activity Concentration Index (ACI) to assess radiation exposure from building materials indoors. The Institute for Building Biology in Rosenheim (Germany) recommends an ACI value of less than 0.75 for health protection.
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Boundary conditions for mobile room air cleaners

Air cleaner Dustcontrol

Air cleaner Dustcontrol


Mobile air purifiers are booming in times of pandemics. Manufacturers of these devices outbid each other with superlatives. The German statutory accident insurance (DGUV) sees the use of the air recirculation units in a much more differentiated way. For example, the accident insurer points out important boundary conditions that must be observed when using the devices in classrooms.
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Strong smell after sanding the floor

strong odor form cresols

Renovating a house from the 1960s

A young family in Thuringia (Germany), full of enthusiasm, renovated a house from the 1960s. They wanted to keep the floorboards on the first floor and started sanding off the top layer. But after a short time the Stickler family was very sober. During the work it started to stink terribly. Ms. Stickler also worried about her child’s health. A building biologist should investigate the process to find the reason for the unpleasant smell. The expert sampled the room air using the TENAX method (2 liters of air at a volume flow of 100 milliliters per minute). As a precaution, he took a material sample from the flooring.
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Tar cardboard containing PAH caused odor problems and headaches

naphtalene found in the air of two classrooms

Naphtalene found in the air of two classrooms

Measurement results showed a pollution with naphthalene

In a primary school in Saxony (Germany), odor problems had arisen in two classrooms and in the staff room since the building was renovated. When a new rector took office in 2018, the matter really got going. Ms. Rubens (name changed) not only had a sensitive nose, but increasingly complained of a headache as soon as she was in the staff room. The school administration informed the city administration as the responsible cost bearer. The local building authority then commissioned an engineering office to investigate the indoor air. The measurement results showed a clear pollution of the room air with naphthalene. Since even the guideline II of the German Federal Environment Agency was exceeded with 20 µg / m³, no lessons were allowed to take place in the rooms from now on. A review of the construction plans showed that the school was built in 1964. Therefore, the experts consulted assumed that the building was contaminated. The energetic renovation in 2017 had obviously exacerbated the smell problem. The airtight facade and the lack of controlled ventilation ensured that the pollutants in the indoor air could accumulate more.
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