Question

what are the three codes of ethics that are used by the organisers of the international Tourism Trade Show in Berlin to reduce their carbon footprint

Answer 1

There were actually more than 3, so I will mention here four of them!

1) you can donate money to compensate for your carbon dioxide emission when flying
2) they exhibition uses only renewable energy sources
3) the exhibition recycles as much of its waste as possible
4)they try to be "paperless" whenever possible - they avoid unnecessary printing!