Research and practice: The window of the future
"Many points can be addressed here - and this is already being done, so the scope is likely to become narrower in future. In the case of glazing, these are new types of coatings, improved spacers or larger gaps between the panes. Highly thermally insulating window frames today are usually composite constructions with an integrated insulating core. Here, the insulation thickness could be increased or materials with lower thermal conductivity could be used. However, almost all measures have side effects: Coating systems with a better U-value often also reduce the heat gains through the window (g-value), which are certainly desirable in winter. Large glass distances lead to increased loads on the edge seal, which can affect its durability. Thick insulating cores usually reduce the stability of the frame, and better insulating materials are often expensive. The same applies to glazing with krypton or xenon filling. Although Ug values of 0.5 or 0.4 W/m²K can theoretically be achieved with these, the costs are much higher than with optimized argon-filled glass, which is around 0.6 W/m²11K. In addition, krypton and xenon are not available in significant quantities." Manuel Demel on the possibilities for window manufacturers to further reduce U-values.
