A crucial property for double-glazed sealed insulating window panes is to maintain their thermal insulating properties and thus low U-values. However, degradation and thus subsequent reduction or loss of low-conductance gas concentration may occur in the sealed glazing units by their exposure to outdoor climate.
The choice of spacers is important to keep as low thermal transport through the window panes as possible, i.e. low U-value. In addition, the type of spacers may also influence their durability and resistance towards ageing, which hence may be characterized by the low-conductance noble gas concentration, e.g. argon, krypton or xenon. Ageing and degradation of window panes may lead to a decreased or total loss of noble gas concentration and hence subsequent increased heating energy demand in buildings.
Thus, several double-glazed sealed insulating window panes, with aluminium spacers and Super Spacers, have been subjected to accelerated ageing by climate ageing and elevated temperature ageing. The durability and ageing of the sealed window panes have been studied and characterized by their spacer type and gas concentration. Furthermore, the decrease of gas concentration in sealed insulating window panes and the impact on the energy performance and in particular heating demand of buildings have been investigated.