Why Condensation on Windows Isn't Always a Bad Thing

External condensation is commonly confused with internal condensation...

...which is a legitimate problem where droplets form between the double glazing.

The issue lies with trying to explain this clearly when making a sale – the VAST difference between internal and external condensation – as saying there is a chance of condensation in cold spells is often confusing and worrying to a potential customer.

As @glazingblogger points out, previous customers often call us around this time of year (or anytime of year where there is a noticeable change of temperature) saing that their units have failed as there is condensation clinging to the external part of their glass (ie. The bit that faces the elements).

What we then have to do is try and clarify that this is not a sign of glass failure, but actually a great sign that the glass is doing exactly what it's meant to.

Droplets on the OUTSIDE = glass performing well

The colder the weather outside (or the bigger the difference between the air inside, and the air outside) the harder the glass has to work to keep the heat inside.

This often results in the appearance of condensation, however, the fact that the condensation in this instance is forming on the outside of the glass (as opposed to the inside, between the glazing) is a sign that the glass is performing correctly and retaining it's heat.

Meaning that the only opportunity water beads are given form is located on the outside of both the glass, and the property.

Loft insulation analogy...

I've also read a great analogy written by the guys over at Lister Trade Frames  , comparing the situation to loft insulation...

On a snowy day, the customer of a loft insulation company may ring them querying why the snow has settled on their roof, when it's melted off all of their neighbour's roofs.

Simple answer – the reason it's melted from the neighbour's roofs is because all of the heat escaping through the loft from the central heating of the house has melted the snow – clearing the roof.

The only reason the snow has not cleared from this particular customer's house is because their loft is so well insulated that very little heat has escaped through the roof, meaning that the roof isn't warm enough to melt the snow.

This is the same reason condensation forms on the external part of a double glazed unit – the glass is doing it's job so well that the heat from inside isn't escaping at all.

Meaning that the only place condensation can form is the outside.

Stay warm this Winter!

So this Autumn, feel safe in the knowledge that those tiny droplets forming on the outside of your glass means that its WORKING!

And you can keep all of your heat where it should be, inside! 

I think this explains the situation pretty well - but of course, if you have any further questions about double glazing or any of our other glass options.. (Ie. Celsius performance glass) please call us on 01454419310 and we'll be happy to talk to you about this issue or any other bifold door queries.