Why Am I Getting Condensation on My Windows?

We are sometimes asked by our customers why they are getting condensation appearing on their newly fitted energy-efficient windows; often thinking that the windows are faulty in some way.

This, we can assure you, is absolutely not the case. It is, in fact, a demonstration that the window is indeed doing its job!

Why windows get condensation on them - Yorkshire Doors & Windows
This excerpt from Pilkington’s website, explains the reason why window condensation occurs.

Moisture condenses out of the air onto a cold surface that is said to be below the dew point. The dew point varies with the air temperature and the amount of moisture it contains. Particularly in spring and autumn, the glass temperature can fall to a low level during the night and the dew point can be comparatively high in these seasons. The glass temperature can be below the dew point under these conditions and moisture can condense onto the surface.

In order to save energy, maintain a comfortable internal environment and satisfy building regulations requirements, the windows we fit in our homes are much more thermally efficient than in the past. With single glazing and older style double glazing, a large proportion of heat was lost to the outside through the glass. With modern low emissivity glass, more of the heat is kept inside and the outer pane is not heated as much.

The more thermally insulating the glass is, the lower the outer pane temperature is likely to be and the greater the risk of condensation on the external surface.

So there is not much that can be done to avoid window condensation in these instances, but it shouldn’t last long. But be reassured that your windows are actually keeping the heat in, and are doing what they have been designed to do.


Image courtesy of Pilkington.