* aluminum on large double glazing on on a new build what happened to upvc?*
All UPVC degenerates over time with UV light from the sun no matter what you are told by salesmen. Ali is a much better product (what I have despite being dearer) Modern stuff has a thermal break and equates with or exceeds UPVC insulation. I believe you are thinking of the original Ali which had a lot to answer for. White powder coated Ali is a lot neater than bulky plastic, I am surprised that anyone would want UPVC anymore.