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The ventilation-replacement in a building

An intensive ventilation of the spaces is necessary in order to exchange the spent breath (higher Carbon dioxide-salary to reduce the atmospheric humidity, contaminant and dust-concentration and the radioactivity. In Sweden, an increase of the dose 110 mrem was determined in strongly heat-dammed apartments until on 380 mrem. (Every radioactive radiation, whether of course or artificially, is live-hostile. Prof. Fritz-Niggli, an air-change from 2 to 3 therefore is commendable. The reduction of this is beside this fact Atmospheric humidity an important aspect of the ventilation.

However, also the chemical contaminants occurring in the building are beside it, the international researcher-community has to the judgment of interior-encumbrances on approximately 20 chemical main-contaminants 1), and the Fine-dust from small 10 micron to heed. Chemical contaminants so frequently come before, as under free heaven approximately ten times. The fine-dust until ultrafine-dust can have to do directly with respiratory tract-illnesses and allergies. They can influence presumably also the heart-cycle-system. To also determine it, however, that represents particularly the smoking or being burned down of Räucherstäbchen the by far biggest air-incrimination. This of evaporations is followed from the kitchen and when heating. An all-year air-circulation is the best means in the building contaminant low to hold. [1]

Our body constantly hands over humidity to the ambient air. As well, humidity originates when cooking, showers and through room-plants. The relative atmospheric humidity rises if this moister air is not exchanged from time to time. If this doesn't take place sufficiently, so the condensate-formation, like earlier at the simple panes, can occur at cooler component parts conceivably or the adjacent atmospheric humidity is higher in this area. This is that cooler air of less humidity can pick up.

Air-requirement
People breathe in oxygen with the air and secret carbonic acid and water vapor. These deceased activity and environment of the human being of the volumes according to weight, food. One reckons 0,02 m3/Stunde carbonic acids per person in the means and 40 g / hour water vapor-production. The carbonic acid-content of 1-3 º/oo stimulates to the deeper respiration, therefore the share should over 1 º in the housing-air as not as possible / oo lies. This conditionally with simple ventilation-change per hour an airspace of 32 m3 for each adult and 15 m3 for each child. (The EnEV stipulates a ventilation-change of 0,6 and 0,7 h-1 respectively.) In accordance with the actual ventilation-part payment, the necessary space-volume is to be chosen.

The mold-formation a wrong ventilation alone, to assign, to reject in principle, is. It for this usually is several causes, for example insufficient Temperierung of the surface or also inexpedient material-usage responsible.
However, mold is created not only at the cold one(s) but also at the warm wall-surfaces, therefore also at a heat-dammed outside-wall, if the corresponding life-conditions exist. These connections become in the mold-book expound. It can also an estimation with one, for example Calculation-tool to the mold-formation is performed.

By the Fraunhofer-institute, the air-change-number was examined. In a table, the values are presented.

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 window menus are unfavorable. As well, tilted window menus bring only a low air-replacement. Is an open window menu or a short cross-ventilation better. The arguments, daily 3 to 4 times powerfully airs, always requires the attendance of a "fan" completely to be silent from the habit and the outlook. Also with absence, the atmospheric humidity increases through the room-plants, for example. The ventilation is the most important measure in order to lower the atmospheric humidity in the spaces.

In Sweden, an additional Zwangsbe and deaeration was therefore introduced. There are simple systems, that only from the bedroom, that the air sucks kitchen and the bathroom and lets stream in the walls of the accomodations through controllable fan-cans according to air. Recently, high-dammed dense window menus with leaky lip-poems are installed in Germany. After the energetic financial recovery installed and constantly current exhaust air-ventilators in the apartment (bath or Water-toilet) should cause an obligatory-ventilation. A shutdown is forbidden of course.

Also the arguments of the "breathing walls" are named. Here, it is meant the sorptionsoffene wall-coating and the diffusion-descent outside surely. Ersteres regulates the dampness-household in the apartment, for example when cooking the water vapor is picked up by the wall-plain short-term and the condensation doesn't settle respectively only little on wall-tiles. Zweiteres becomes through the more outer wall-coating, for example with a synthetic resin-coating or the heat insulation system, stopped most extensive. In the extreme-case, humidity can accumulate in this border-work period. Altogether, relatively little humidity is served as through the diffusion outside.

But, and this is forgotten with the ventilation-argument, only over the unobstructed diffusion, the wall-construction can remain dry. If the wall is wet, so the thermal conductivity increases extremely per construction-material and the consequence is a high consumption of heat-energy. In an extreme case in Zwickau (2001) to an unheated staircase of about, the unit of heat-transfer of an inner-wall of concrete changed. 1,9 W/m2K on over 4 W/m2K. In the following table, the humidity led away from the space is compared by diffusion and ventilation in dependence on the outside-air-temperature.

Temperature of the outside-air [ºC] Diffusion in the outside-wall [g/h] (dependent on the size and the wall-setup / materials) through simple air-changes (dependent on the space-volume, the inner-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 stands in the contradiction by the old WSchVO 95 and the new EnEV.

Wide one part 2

1)Das Umweltforschungszentrum (www.ufz.dewww.ufz.de hat die Zahl längst auf insgesamt 120 Substanzen erweitert.

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