External Condensation

The cold mornings are rolling in and many homeowners who have had the very latest high-performance windows installed may be encountering an unusual phenomenon

Condensation on the outside of the glass

External condensation may occur on the latest energy efficient double glazed windows and demonstrates that the windows are doing a fine job of keeping heat in the building. … The phenomenon is a natural and predictable event caused by the outer pane of the glazing being colder than the glass that it replaced

You may be asking yourself though, “why didn’t I see this on my old windows?”

The reason you didn’t notice this on your previous double-glazed windows was that they weren’t particularly efficient. The sealed glazed units must have been allowing enough heat to escape from inside the house that the outer panes of glass were kept above dew point temperature. Hence no dew formed on them (although it will still have been forming on the outer surfaces of your walls, where you wouldn’t have noticed it)

So don’t worry. If after your new windows have been installed you experience external condensation, it simply means your windows are performing at their peak

Internal Condensation

Windows do not and cannot cause condensation as they do not generate water

However, depending on the humidity in the room, or outside (for possible external condensation), condensation could fall on a window - although this has been greatly reduced over the years through advancements in insulation

A well-ventilated house is essential to help avoid condensation, and improve your wellbeing

Every homeowner should own a hygrometer that measures temperature and relative humidity (RH). The ideal relative humidity for health and comfort is about 40-50%. In the winter months, it may have to be lower than 40% RH to avoid condensation on the windows

Download Condensation - Some causes, some advice

An independent guide kindly written by the GGF Glass and Glazing Federation

An independent guide kindly written by