All other things being equal, is there any advantage over 4/20/4, over 4/16/4? This is assuming argon filled and one pane low e glass.
Getting quotes at the moment uPVC windows, some offering 4/20/4 and others 4/16/4, both quoting 1.6 or under 'u' value.
Getting quotes at the moment uPVC windows, some offering 4/20/4 and others 4/16/4, both quoting 1.6 or under 'u' value.