That is what we’ve heard many times since beginning the planning process for our new energy efficient house. The most extensive argument may well have been around the merits of triple-pane windows. In northern Europe triple-pane windows are now standard for new construction, and Canadians use them already extensively. But here in the US energy awareness is still in its infancy and we kept being asked “what do you want to do that for?”
In comparing windows, I found that Canadians build better frames, which makes a big difference, and they use orientation and climate specific glazing for optimal energy savings. European casement windows have a much tighter fit than the double-hung windows typical for here because of the different frame design. Passiv-Haus windows are the platinum standard, it tops them all (price included!).
Thinking ahead, Germans are already talking about quadruple windows!