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How to avoid proper ventilation and condensation, molds and pollutants

Proper and intensive ventilation of the rooms is necessary to exchange the used air (higher carbon dioxide content), to reduce the humidity, the pollutants and dust concentration as well as the radioactivity. A sufficient reduction is therefore only possible via the ventilation through the windows.
Ventilation systems offer good growth conditions for germs, if these are not regularly maintained. Moisture can accumulate in the pipes. Together with warm air and dust, these form excellent nutrients for bacteria and fungi. The radioactive dusts remain somewhere in this pipe system or in the filters, and therefore do not leave the house. The following article addresses the need for proper ventilation.

All opening of the ventilation system in a large hotel complex was cleaned. Only two pieces had been forgotten to clean. How it could look like in the pipe system can only be guessed.

Contaminated ventilation opening

In Sweden, an increase from the dose of 110 mrem to 380 mrem was determined in strongly heat-insulated dwellings. (All radioactive radiation-whether natural or artificial-is hostile to life, Prof. Fritz-Niggli) The air-to-air ratio of 2 to 3 is recommended. Similar findings with health effects on residents as a result of heat protection measures were reported in the new study (2015) "Are our homes making people sick?" made.
In addition to this fact, the reduction of humidity is an important aspect of ventilation.

In addition, the chemical pollutants present in the building are also contaminated with chemicals, and the international research community has agreed on the assessment of indoor air pollution to about 20 chemical main pollutants 1) and the fine dust of less than 10 micrometers. Chemical pollutants occur about ten times as frequently as in the open air. The fine dust to ultrafine dust can have directly with respiratory diseases and allergies. You may also influence the cardiovascular system. However, it is also important to note that the smoking or burning of incense sticks is by far the greatest in air pollution. This is followed by exhalations from the kitchen and during heating. A year-long air circulation is the best means to keep contaminants in the building low. [1]

The Energy Savings Order (EnEV 2014), Renewable Energies Act (EEG), EEWärmeG, BImSchV, ventilation concept obligation (DIN 1946-6) and heating cost regulation are used in Germany to save energy. The new savings laws and regulations and / or the new innovations must be considered. These have to be taken into account since 2009 with every new building application or a building advertisement. All together means further tightening up of energy savings as well as strict fines in case of violations of the new editions.
But for reasons of hygiene a minimum air change must be observed. In addition to a balanced insulation concept, the requirements in DIN 1946-6 also require the planners to plan a coherent ventilation concept. The legal situation: mold fungus is designed as a structural engineering fault at the expense of the owner or planner. DIN 1946-6 is referred to as a recognized rule of technology. (This is a comment on the DIN.) This will perhaps apply to Germany. In other countries thermal insulation and ventilation have a different view.

Our body constantly releases moisture to the room air. It also creates moisture during cooking, showering and by planting plants. The relative air humidity increases when this humid air is not replaced from time to time. If this is not sufficient, condensation may occur on cooler components, as in the case of simple window panes, or in this area the adjacent air humidity may be higher. This is because cooler air can absorb less moisture.

The air in an apartment

Humans breathe oxygen with the air and exude carbon dioxide and water vapor. These vary according to the weight, food, activity and environment of humans in quantities. The average per person is 0.02 m3/hour of carbonic acid and 40 g/hour of steam generation. The carbonic acid content of 1-3 º/oo stimulates deeper breathing, so the proportion of the air in the home should not exceed 1 º/oo. This results in an air volume of 32 m3 per hour for every adult and 15 m3 per hour for a simple ventilation change per hour. (The EnEV prescribes a ventilation change of 0.6 and 0.7 h-1, respectively.) The space volume required must be selected according to the actual ventilation rate.

The mold formation alone is attributable to a false ventilation is to be rejected in principle. There are usually several causes, for example inadequate temperature control of the surface, diffusion-tight wall coatings and too small a space volume. However, mold fungus does not only develop on the cold, but also on the warm wall surfaces, ie also on a thermally insulated outer wall, when the corresponding living conditions are present. These connections are explained in the Schimmelbuch. For example, an online calculation for mold formation can also be performed.

The Fraunhofer Institute investigated the number of air traffic. The values are listed in a table.

Ventilation-typeAir-change-part payment of hourLast the ventilation for an air-replacement
closed Window menus and doors0,0 to 0,5at least 2 h. (the denser
the window menus, so the value is directed against endless
Window menus tilted0,5 to 2,00,5 h. until 2 h.
half opened window menu5 to 106 to 12 min.
completely open window menu9 to 154 to 7 min.
Cross-ventilation401,5 min.

Very dense windows are unfavorable. Likewise, tilted windows bring only a small air exchange. Better is an open window or a short cross-ventilation. The arguments to air vigorously 3 to 4 times a day always require the presence of a person in the apartment, not to mention the habit and the attitude to the air. Even in the absence, the humidity increases, for example, through the indoor plants. Ventilation is the most important measure to reduce the humidity in the rooms.

In Sweden, an additional forced ventilation system was introduced. There are simple systems, which only suck the air out of the bedroom, the kitchen and the bathroom and let air flow through the walls of the living rooms through adjustable ventilation sockets. In this way, the mold formation in the bathroom can be avoided - for example, on bathroom faucets, in joints of bathtubs, showers and washstands as well as on window reveals.
In Germany, highly insulated, dense windows with leaky lip seals are installed. After the energetic refurbishment built-in and constantly running exhaust fans in the apartment (bath or toilet) are intended to effect forced ventilation. A shutdown is of course prohibited.

There are no "breathing walls". Important are sorption-free wall coatings, which can absorb moisture quickly during cooking or showering. In the case of wall tiles, the moisture condenses as condensation. This high humidity must then be vented accordingly. Then there is the diffusion gradient from the inside to the outside. The entire wall structure must not have any blocking layers or boundary layers. This can lead to moisture and, in the worst case, the entire cross-section of the construction is moistened. Such barrier layers can occur, for example, in a synthetic resin coating or in the heat insulation composite system. On the whole, relatively little moisture is released to the outside because of the diffusion in relation to a correct ventilation.

But, and this is forgotten in the ventilatory argumentation, only through the unimpeded diffusion can the wall construction remain dry. If the wall is wet, the thermal conductivity per building material is extremely high and the result is a high consumption of heat energy. In an extreme case in Zwickau (2001), the U-value of an inner wall made of concrete changed to an unheated staircase of about 1.9 W/m2K to over 4 W/m2K. This enormous deterioration was the result of long-term moisture penetration through condensation on the wall in the kitchen.

The following table shows the moisture discharged from the room by diffusion and airing as a function of the outside air temperature.

Temperature of the outside-air [ºC] Diffusion through the outer wall [g/h]
(Depending on size and wall construction/materials)
By simple air exchange
(Depending on the volume of the room, the temperature and humidity and the humidity of the outside air.)
- 20 5,5 436
-10 4,8 378
0 3,2 242
+10 0,4 15

However, the necessary ventilation is in contradiction to the old WSCHVO 95 and the new EnEV.

In a study, the passive house institute has the following results: "Improving air tightness in buildings with window ventilation to the demand level of buildings with air conditioning systems is a very economical energy saving measure and it was assumed that these values can be achieved with an air tightness measurement [2]

Wide one part 2

1)The Umweltforschungszentrum (www.ufz.de) has extended the number to a total of 120 substances.


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