Insulated Glazing - Longevity

Longevity

The life of an IGU varies depending on the quality of materials used, size of gap between inner and outer pane, temperature differences, workmanship and location of installation both in terms of facing direction and geographic location. IG units typically last from 10 to 25 years, with windows facing south (Northern Hemisphere) or the north (Southern Hemisphere) often lasting less than 12 years. IGUs typically carry a warranty for 10 to 20 years depending upon the manufacturer. If IGUs are altered (such as installation of a solar control film) the warranty may be voided by the manufacturer.

The Insulating Glass Manufacturers Alliance (IGMA) undertook an extensive study to characterize the failures of commercial insulating glass units over a 25-year period.

For a standard construction IG unit, condensation collects between the layers of glass when the perimeter seal has failed and when the desiccant has become saturated, and can only be eliminated by replacing the IGU. Seal failure and subsequent replacement results in a significant factor in the overall cost of owning IGUs.

Large temperature differences between the inner and outer panes stresses the spacer adhesives, which can eventually fail. Units with a small gap between the panes are more prone to failure because of the increased stress.

Atmospheric pressure changes combined with wet weather can, in rare cases, eventually lead to the gap filling with water.

In Canada, since the beginning of 1990, there are some companies offering restoration of failed IG units. They provide open ventilation to the atmosphere by drilling hole(s) in the glass and/or spacer. This solution often reverses the visible condensation, but cannot clean the interior surface of the glass and staining that may have occurred after long term exposure to moisture. They may offer a warranty from 5 to 20 years. This solution lowers the insulating value of the window, but it can be a "green" solution when the window is still in good condition. If the IG unit had a gas fill (e.g. argon or krypton or a mixture) the gas is naturally dissipated and the R-value suffers.

Since 2004, there are also some companies offering the same restoration process for failed double glazed units in the UK, and there is one company offering restoration of failed IG units in Ireland since 2010.