I'm not sure how important double glazing is when you're opening the inner air volume to ambient air every few minutes, but maybe?

It's possible something could be done about that with air curtains, PVC strip curtains, etc.

Climate control energy varies widely depending on geography - and appropriate door energy saving approaches will probably depend on where the bus operates, and possibly even the season (ie. winter doors swapped for summer doors), or extra batteries added in summer/winter to account for the extra energy use.