External Condensation

What causes condensation on the outside of new windows?

One of the many reasons we replace the windows and doors in our home is for better energy efficiency.  UPVC windows and doors are designed to be as energy efficient as possible.  At times you may see condensation on the outside of your new windows and doors.  What causes condensation on the outside of new windows and why does it happen?

Understanding condensation on the outside of double-glazed windows.

UPVC types of modern replacement windows feature a frame design and materials that provide insulation for the entire window and prevent the cold from the outside transferring to the inside.  They also prevent the heat inside your home from escaping to the outside.

As well as advanced frames, the glass we use is also latest generation and specification working together with your window frames. 

Condensation on the outside of new windows is normal.

Condensation on the outside of new windows does not mean they are faulty. It is simply the windows doing their job of keeping your home more energy efficient.

Condensation will form on any surface as soon as the surface temperature falls below the dew point of the air.

During the Autumn and Winter months the phenomenon of condensation on the outside of your new windows and doors will be more frequent. Where previously the heat was escaping and the cold was entering your home, your advanced windows and doors are so good, the heat is staying in your home and the cold is being prevented from entering it.  The outside of your window is now colder than the glass or the window it replaced.

A great example is defrosting a frozen windscreen on a cold morning.  Your car heating is warming up the windscreen from the inside, the heat is passing through and defrosting it on the outside.  An energy efficient window prevents the transfer of heat.

Helping you understand external and internal condensation.

Internal condensation is usually caused by how we live in our homes and the amount of moisture we create from cooking, heating, drying clothes inside and not ventilating our homes enough.  Often this is the cause of internal condensation and not just on windows and doors.

External condensation is the opposite, with moisture remaining on the outside and landing on the first cold spot it finds, in this case the outside of your windows.

Finally, if you see condensation between your panes of glass this means the sealed unit has failed and will need replacing.  This is common on very old double-glazed windows.

Any condensation on the outside of your windows and doors will disappear as soon as the outside temperature starts to rise.  Your new energy-efficient windows are keeping your home warmer, more comfortable and more secure than ever before.

Condensation on the outside of new windows means windows are performing well.

See Pilkington's response to cause of condensation in PDF Below