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(This page was automatically translated from German. Wärmeisolierung)

Function-sage the heat insulation / heat-isolation

KonvektionsstömungThe heat-isolation has a big meaning in almost all areas of the technology. The tasks is to hold the heat-fluxion small. The bad heat conduction of the gases becomes with the heat-heats insulation. = used 0,01 - 0,2 W / mK. With gases, it takes. with climbing temperature and pressure to. However, it doesn't suffice to intend only one gas-work period (picture 1).

Mistakes at implementation of a heat insulation

Form 1: Convection-stream in a heat transferring gas-work period

The gas-work period-thickness δ a multiple of the heat, that through-goes on the basis of its heat conduction, transfers since a heat of transporting convection-current appears. That is also a big problem with the implementation of a heat insulation, for example at a house, if intervals or BFUs are built. In the right picture (2), different mistakes are shown with the publishing of a heat insulation. With all three cases, a convection-current can refine 1 in the heat insulation-work period like in the picture. At these positions, dew-water or it refine, dark shades become visible after some time. (See Fogging
So that a low thermal conductivity becomes the gas noticable, convection-currents must be stopped wideness-well-doing. This is reached, in which the gas-work period is shared into many small gas-cells. cotton wool-good structure heat insulationThe separating wall cell must as thinly as possible, badly heat leading and badly heat beaming is. In the picture 3 is a froth - and cotton wool-good structure represented.

Form 3: a, yeast-good structure (b) cotton wool-good structure of the heat-insulation


Thermal conductivity of heat insulationThe more finely the structure is, the better quality of the heat insulation is. Borders are placed technical here. In the picture 4, some heats insulation are presented. With increasing heat, also the thermal conductivity takes reduced to respectively the Dämmeigenschaft sights.

Form 4: Thermal conductivity selected heats insulation
1 silicious earth-stones, burned 500 kg/m3
2 cinders-wools 400 kg/m3
3 asbestos-mats 300 kg/m3
4 wrinkle-sheets 3 kg/m3
5 glass-wools 120 kg/m3
6 Alfol 5 kg/m3
7 yeast-polystyrenes 20 kg/m3
8 Kamilitmatte 100 kg/m3


Feuchteverhalten von Dämmstoffen

Particularly the heat insulation must be kept dry since the stored dampness in the pores leads the heat better than gas about a multiple. Already with a dampness-salary of 1 per cent, the Dämmwirkung halves from mineral-fiber, for example. (Form 5, It therefore is very important that the heat insulation always is in a dry status. With an unchecked Durchfeuchtung, an Abtrocknung must therefore be guaranteed. With an inner-heat insulation, steam-brakes come to the usage.


Form 5: Dependence of the thermal conductivity on heat insulation at moisture-alterations


Here still a case in point of a retroactive outside-heat insulation (6 cm and 12 cm) of a 36.5 cm of outside-wall.

The costs for a thermo-skin become for 6 cm with about. 60 Euro / qm and for 12 cm with 75 Euro / qm boasts.(Rötzel, whether here the consequence-costs, for example, for the erection of a bigger eaves etc.. considered, cannot be named. You/they save about with a 12 cm of heat insulation opposite one with 6 cm. 0,2 W/m2 in the hour. With a temperature-difference of 20 K is the 4 W. One would have to insert exactly the average Heiztage per year here. Strongly, the additional costs would be simplified again approximately been obtained after 10 years. Since the values represented in the drawing are theoretical and a low restriction takes place in the practice, sees atmospheric humidity to this), point 2.3. Heat-demand for energy and the redevelopment-costs. The additional costs, that are served with a capital-service normally, postpone the Beak-Even-Point in direction 20 or more years so. Into this time, however, the sanitation of the thermo-skin falls also once again. With

Short-description of the qualities of heats insulation:
Mineral-wool / stone-wool
XPS-Extrudiertes polystyrene
Pure-polyurethane (hard-yeast-plates)

König, Holger; Das Dachgeschoss, 3. Aufl., ökobuch Staufen bei Freiberg, 1996,, S. 51
Meyer, Günter; Schiffner, Erich; Technische Thermodynamik, 2. Aufl., Fachbuchverlag Leipzig, 1983, S.209
Rötzel, Adof; Praxiswissen Umweltfreundliches Bauen, 2005 Verlag W Kohlhammer GmbH Stuttgart, S. 110

Ingenieurbuero Peter Rauch

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