Condensation on your windows

At this time of year do you suffer from condensation on your windows in bedrooms?

We have noticed it in a lot of homes even with newly installed double glazing and this shows a potentially large problem or two.

Take for instance the windows. If they are double glazed there is no way that they should have condensation on the inside pane of glass. If they are affected by condensation it is probably because the gap between the glass is not sealed and filled with inert gas like Argon it is just filled with normal air (not even dried filtered air) and this is very common in Portugal.

For independent information, we recommend you take a look at.

A double glazing window comprises two panes of glass, separated by a spacer bar and seals to create a hermetically-sealed environment. The cavity width between the two panes, air or another gas filling used and the type of spacer bar, are all key factors in the unit’s final energy, solar and acoustic insulation properties. Which dictate condensation or not!

The cavity is filled under vacuum conditions with either dehydrated air or an inert gas to improve insulation and prevent condensation within the unit. Depending on the gas filling used and the type of window, the cavity width for a double glazing window is generally between 4 to 20 mm.

Condensation on your windows, castelo construction, portugal builder,builder in Portugal
Condensation on your windows

The recommended cavity width for Low E energy saving double glazing window when filled with dehydrated air is 16mm – and 14mm when the cavity is filled with argon gas.

Less heat transmission with double glazing window and a warmer home

The physical properties of the dehydrated air used in the cavity means that it transmits (ie loss) less heat by convection or conduction than normal air. This is because the molecules of dehydrated air are relatively immobile, and therefore have a ‘lower thermal conductivity’. The same physical properties of dehydrated air also give it lower acoustic conductivity, for improved sound insulation.

If normal atmospheric air is used the performance of the panel’s is further reduced.

Double glazing window energy efficiency can be further increased by substituting dehydrated air with an inert gas, such as argon, xenon or krypton within the unit. Argon, which has 34% lower thermal conductivity than air, is the most commonly used. Although argon-filled units cost around 5% more than air-filled units, they can improve a double glazing window’s U-value or energy rating by over 30%. Argon fillings should last the lifetime of a double glazing window and over a period of 25 years should not lose more than 5%.

Which begs the question – Why do the local window suppliers do it. Use air I mean it can only be because they make more profit.

If you are buying windows in Portugal ask the supplier to give you a written assurance that an inert gas has been used to fill the glazing panels.