Any glass holds the heat in the house much worse than the walls. It is thanks to the windows and doors that the heat of the house is loss of up to eighty percent. However, the metal -plastic systems of windows, widely represented in the modern market, are much more effectively held by the heat in the room, unlike their wooden predecessors. Many people believe that condensation formed on double -glazed windows is their significant drawback, however, it should be taken into account that it is formed due to the natural physical process. So that the condensate does not form, it is often necessary to ventilate the room, so that the humidity in the room returns to normal.