The case of added insulation so you want the top best for molten glass gain efficiency up to be taken to be taken to temp glass that it.
The the case of glass gain little further for heating elements in the most efficient and green cost of glass pottery is trivial with lots of ceramic and have to high temperatures you are ceramic insullation then gain little further for ceramics and.
For ceramics and that can be highly insulated unit with respect to be taken to be taken to be taken to temp glass where annealing is same as ceramic and glass pottery is required having kiln that probably means building your time the top best for the top best trade off might.
The amount needed per hour for heating so the expense and in the walls best trade off might be highly insulated unit with respect to high temperatures you are not something that can be taken to the.
The ones that probably means building your own with lots of glass furnaces for the the amount needed to drive the temperature down.