the greenest option
The problem with slimline double-glazing
There are many fine woodworking businesses offering sash window services, but, regrettably, few of them appear to know much about double-glazing. The use of solid-bedded ultra-slim sealed-unit double glazing is fine if you don't mind seeing the headlines that we saw back in the early 1980s.
Here's one I recall from the Sunday Mercury, a midlands regional newspaper of the time.
Most of those advocating the dodgy glazing techniques that brought double-glazing of wood windows into disrepute twenty-five years ago are too young to remember the problems, but those who prosecute cases through the courts remember them well, and are licking their lips at the prospect of more easy business. Don't believe me? Follow this link to a specialist glazing website for an independent surveyor's view:
Being a fine joiner is simply not enough in this technological era. Take care to do your research and establish the facts BEFORE you spend your hard-earned money.
The fact is, to be certain it will last, double-glazing MUST be installed in such a way that the edge seal is in contact with nothing but fresh air. If water does get in to the frame, it MUST be provided with a way out. This is called "Dry Glazed, Drained and Vented". Aluminium and PVC windows have been built like this from the start, but many wood window makers - fine joiners though they may be - simply either don't know this, or don't believe it.
Remember to ask:
Is it dry glazed, drained and vented to GGF Best Practice?
If it's not SupaSash, it probably isn't.
Specify SupaSash for peace of mind.