Misty Glass Units

Condensation when it forms on double glazing, tends to form in ONE of three places. Either, 1) on the inside of the inside glass pane, 2) in-between the two glass panes or 3) on the outside of the outside glass pane.

Double glazed sealed units have only broken down if moisture or “misting” appears in-between the two glass panes. Any slight moisture or misting means the unit needs replacing, as over time the amount of moisture and misting will increase, making the window look unsightly.

More importantly, it is clearly no longer a “sealed unit”, so will not be performing the function of a modern sealed double glazed unit, which is to keep the cold out, energy generated by your heating system in and allow solar gain to be retained within the dwelling.

Condensation on the inside of double glazing means there is a ventilation problem within that particular room and/or property that needs addressing. Conversely, condensation on the exterior means the double glazed unit is performing exactly as it should and you will notice it disappear throughout the day as the sun rises. The latter tends to occur in late Autumn, and is not usually a phenomena that lasts for too long. Quite often a picture frame effect will be created by misted squares or rectangles on the glass, surrounded by a clear outer “glass frame”. Yes, it is strange that this is actually “proof” the double glazing is performing efficiently, but better to have damp forming outside your windows than inside your house!

For UK home owners with contemporary energy rated aluminium or UPVC double glazing, replacing broken down sealed units is simple and easy to do. Properties with very old fenestration systems or timber double glazing many find replacement more costly, especially if the units are secured in the frames with putty rather than wooden beads.

While replacing sealed units that have broken down is not that important during the warmer summer months, it is vital to have the work done prior to the onset of Winter, as broken sealed units are leaking  expensive energy out from your home into the environment, making your heating system work harder than need be. Aesthetically failed sealed units can be very unsightly, so all in all they are worth replacing to make the windows and/or doors the defective sealed units are in, once again become energy efficient.

Contact us at Hall & Jones Windows, Doors & Conservatories for more information on Misty Glass units and how we can help.

Condensation on windows and in conservatories, and the damage it can do to paintwork, curtains, wall coverings and window fittings, are problems sometimes encountered in all types of building.

Modern aids to home comfort have created rooms which are warmer but which often have less ventilation and fewer air changes. The result is that the water vapour produced by normal living activities is no longer able to escape up the chimney or through door jambs, window joints and other outlets.

In certain circumstances, all these aids to comfort combine to create ideal conditions for the formation of condensation, which could form on the coldest surface within the room. This may not necessarily be on the glazing.

The question of how to reduce condensation without sacrificing the benefit of increased

Due to recent innovations in the efficiency of double and triple glazing, along with updated requirements of building regulations and the lowering of carbon emissions, certain weather conditions may allow the formation of external condensation on energy efficient windows and doors.

This is a natural phenomenon and a clear indication that the window or door is preventing heat loss from your house.

Double or triple glazing is an insulator, designed to reduce the loss of heat by conduction from the inside to the outside of a building. Current Building Regulations, specify that all new or replacement windows must meet a minimum performance criteria. This requirement can only be met by the installation of energy efficient windows and doors.

Under average exposure conditions, and provided the room is heated, the room side surface temperature of the inner glass will be higher than would be the case with single glazing.

The likelihood of condensation occurring when warm moist air in the room comes into contact with the surface of the glass is thereby reduced.

It must be remembered, however, that double or triple glazing is an insulator and not a source of heat; it does not control the amount of water vapour in the air. When rooms are inadequately heated and there is little heat to retain, double glazing cannot fulfil the purpose for which it was installed.

One reason why condensation forms in a room not normally occupied is that many householders, for reasons of economy, do not heat such rooms. Consequently the surface temperature of the inner glass gets very close to the outside temperature.

In addition, the windows in such rooms are generally kept closed, but water vapour, generated elsewhere in the house, will find its way in and then not escape. Thus the two conditions necessary to produce condensation – a low glass surface temperature, and high water vapour content in the atmosphere – are present.