"Mike Mitchell" wrote
| Are Crittall's steel-framed windows of yore that much worse for
| insulation than cheapo plastic-framed double-glazed units?
| In terms of heating bills, how long would it take to amortize
| the cost (ca. £5,000) of replacing steel-framed windows with
| the uPVC variety?
| I reckon it would take literally years before one had paid
| off the costs through fuel savings.

Quite possibly longer than plastic windows last.

If your windows are old and draughty you could consider replacing them with
new Crittall windows - they're still made, but to updated standards of
insulation - which might be more in keeping with the period of your
property.

Owain