My son has just moved into an ex Council house, built to a high standard with 16(!) windows.  They are absolutely strapped for cash - so no money for replacement windows.  

The windows are Council specials from about five to ten years ago - standard UPVC windows but single glazed. I seem to remember the same frame being used for double glazed windows as well.

The frames, hinges etc are in excellent condition.

Can I simply buy double glazed inserts, and a narrower bead and therefore reuse save the old frames?  It would save a fortune, and we could start with the coldest rooms first. .

Otherwise would it be an idea to fit UpVC units on a wood frame as secondary double glazing  to the living room (the coldest room in the house, and probably Europe!) I assume fitting double glazed units would get round the normal condensation problem with single secondary double glazing.

Also will have to fit UPVC windows to our own house soon - I haven't got the money for Everest either - anyone any tips, or links to useful websites.  

Ta

John D