Understanding external condensation
The sight of condensation on the inside of our windows is something most of us recognise or, if we’re lucky enough to have well-insulated homes, we certainly remember. It marks the start of colder days and nights outside, and cosier days at home.
It’s well known that when condensation forms on the inside of windows, it’s because they are not efficiently double or triple glazed and, importantly, there is insufficient controlled ventilation. Therefore, the water vapour within the home has nowhere to go other than to liquify on a cold surface – a pane of glass.
Conversely, the better insulated the home, the more likely condensation is to form on the outside of windows, and, whilst this is much less problematic than internal condensation, it is something that customers ask us about.
Why does external condensation form?
Through using the latest glazing technologies, it is now possible to achieve excellent results with home insulation, which not only leads to warmer homes, but cost-efficiency with lower heating bills and, from an environmental perspective, lower energy consumption.
However, this improved internal insulation can lead to external condensation; because the outermost glass isn’t heated, on colder days condensation forms due to a combination of humidity and the glass having a temperature below the ‘dew point’.
The diagram below visualises the efficiency of multiple-glazed windows:
A bright outlook
The good news is that external condensation is unlikely to cause damage, as it is usually air or sun dried during the day, which means the moisture doesn’t stay around for more than a few hours.
External condensation tends to be worse on some windows than others, depending on their aspect; i.e., how much sunlight reaches them and how sheltered they are. It is also more prevalent for houses near expanses of water such as rivers or lakes, where the humidity will be naturally higher.
With conservatories, where a condensation-free outlook is preferable, we always recommend using specialist glass, such as Pilkington’s ActivTM self-cleaning glass. This has a hydrophilic coating that repels water, which minimises condensation.
Help with condensation
External condensation is usually a good indication that your windows are efficiently insulated. However, if you have internal condensation, you could solve this, and achieve savings on your heating bills as well as your energy consumption, by upgrading to better insulated windows.
Our expert team are on hand to talk through the options. To book a design consultation, please call us on 01444 45 71 45.