Blog: Window Condensation

At this time of year, we see an increase in the number of calls regarding condensation. Many people find that with their new windows, comes condensation, and this is often an unwelcome surprise.

Although it may not be welcome, do be assured that condensation on the inside and/or outside of your windows is proof that your new windows are doing their job of preventing heat loss. What you are seeing is energy efficiency in action.

Often, we replace our windows because they are no longer energy efficient. They may be old windows with single glazing, or double-glazed windows that are long past their best. Condensation doesn’t get a chance to build up because enough air passes through the frames. This is not a good thing and will be one of the reasons you decided to replace your windows in the first place. Your new windows will be modern, strong, weatherproof, safe, secure and of course, energy efficient.

What causes internal condensation?

Condensation on the inside of our windows and doors is the result of water vapour having nowhere to go. Water vapour is caused by everyday things such as breathing, cooking, drying clothes, bathing/showering, etc. We can generate 1 – 2 litres of water vapour every day simply through breathing! A 3 person household can generate approximately 180 litres – more than a bath tub of water – every day. It is essential, therefore, that the correct amount of airing and ventilation occurs.

Simply opening a window and airing a room for 10-15 minutes a day will make a massive difference to the build-up of moisture in the home and is enough to exchange the air in an average sized room. Walls act as storage heaters meaning that when the windows are closed again, the warmer temperature will quickly return.

What about external condensation?

External condensation is far harder to control but it is a temporary phenomenon which you are most likely to experience during Autumn and Spring when the British climate changes. It is quite common to experience external condensation on some windows and not others. This is due to the location of the window, which way they face, and whether or not they are sheltered from nearby trees or buildings. Once the sun is up and the heat has warmed up the outside of your windows, the moisture will evaporate. External condensation is an indication that your windows are thermally efficient and are preventing heat loss from your home – which can reduce your energy bills! A much more welcome surprise!

Download the GGF Condensation Brochure