The last time I checked, AV systems didn't emit any kind of harmful gasses or have emissions problems
Other than using all RoHS certified equipment, I don't see any way to achieve anything "Green" in AV system design. They (AV systems) consume far less energy than almost any other facet of a facility, so they are already kinda green anyway. Oh, and you can forget using the new Soundweb London's. They aren't green anymore either.
Just wait a year or two, and there will be another universe saving bandwagon to jump on.
Paul