Not too sure about buildings, however the only green coloured exit signs I have seen in buildings, are (as far as I know) just that, signs lighting the "normal" exit path from the building, NOT "emergency" exits.
Of course with an Aircraft, the "normal" exits (like say the front door) are also "emergency" exits in an emergency situation, and as such definitely always have red signage.
This regulation is so strict in the USA, that we had a run in with an FAA Inspector a few years ago at JFK, because he thought our Australian registered Aircraft had the wrong shade of red exit signs.
