[svandamme]

those values i listed, are real, i just ordered my glazing last week.
So if you have a 1.5 C difference on the panes, and you install it in an old house that's not much difference, and it won't be worth the investments since the walls will be less insulated then the panes..

Tripple glazing is only cost effective if the rest of the house is built up to modern, passive house standards... or if you live in Scandinavia or Alaska (where the houses would also be built with better wall insulation anyway)...