mrgrimsdale wrote:Brian got there before me! If you factor in obsolescence its a different picture - DG units last 10/20 years, trad sashes last 100/200 years.
It's a no brainer, you hardly need to do the sums.
But the stats you were quoting must be based on full replacement, so are totally misleading in terms of payback time.
That kind of catastrophic failure ^^ must be very rare. So you are really dealing with misting up problems - no reason in theory why the units can't be split and remade, with minimal enviro impact (whether that's ever done in practice is another question).
I've got hideous late 70s/early 80s aluminium windows some previous idiot installed on our frontage - no problems with them at all (apart from their total hideosity) and they must be getting nearer to 30 years old.
No doubt the whole uPvC/replacement for replacements sake is nonsense, but if the window is beyond repair (or it's a new opening), and the window frames/sashes need replacement anyway...