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ISSUES REGARDING CONDENSATION ON WINDOW GLASS

Condensation on window glass is quite a burning issue. At the beginning it is important to point out that no window or glass makes water. The water "running" across the glass results from a physical phenomenon called condensation of the ambient air humidity, which cannot be removed completely, but under certain conditions we can reduce it.

The air contains water vapour, the amount of which is limited and depends mainly upon temperature and relative humidity.

The crucial factors that influence condensation forming on glass are the following:

external temperature (when it is freezing, the outside of a building gets colder, including the window glass);

room temperature and indoor humidity (the major sources are breathing, especially in one's sleep, then drying the washing, cooking, house plants, etc.);

thermal insulation properties of glazing – i.e. the amount of cold air the glass transmits from the outside;

air circulation near the window – i.e. whether the heating is turned on below the window, which warms up the glass;

regular and thorough ventilation of a room so that the warm and humid air can be exchanged for dry and cold air from the outside, which gets warm much faster (and is therefore cheaper).

The problem of condensation is almost eliminated with scuntion windows where there is a double-glazed insulating unit (Ug = 1.1) in the outer window, including seals and circumferential fittings. A single piece of glass in the inner window is at room temperature and therefore condensation hardly ever occurs there.

If, however, an investor demands single glazing for the outer window and a double-glazed unit for the inner one, the external glass gets so cold that the indoor humidity can condense on it.

Single windows with double-glazed insulating units, sealing and circumferential fittings (Euro windows) obviously have colder glass, which, under certain conditions, can become a target for the condensation of inner humidity. The thermal conductivity of walls (U factor) is much lower than that of glass or the whole window. Nevertheless, if the above recommendations are observed, condensation should not form.

In the event of extreme frosts some condensation can appear on window glass. In such cases it is important to heat and ventilate the room sufficiently and wipe excess condensation off your windows.

We are convinced that except for extreme climatic situations you should not encounter the problem of condensation if you follow the usual measures for using windows which are made in compliance with the ČSN binding standards, are certified (which you can verify by requesting the window certificate) and are properly assembled (anchors, foam, compression tape, etc.).

Therefore we believe that you will not have to face the above-mentioned problems.


Since 1998 we have installed as many as:

9 636 scuntion windows
19 074 euro windows
852 doors