Take the words “installing double or triple glazed windows” for instance. Does that only include the glass or the glass AND the frame?
I don’t think you can separate the glass from the frame in double glazing. The government has moved the definitions of sustainability renovations from the sustainability clause to just making them minor renovations under section 28 of the Regs.
Your problem may be that you are referring to doors wheras the Act refers to windows.
Double-glazing is a sustainability issue becaus it reduces the need to artificially heat or cool.