In December 2009, during the United Nations’ 15th Climate Change Conference (COP15), Siemens AG and The Economist Intelligence Unit (a division of The Economist magazine), released the European Green City Index, a rating of the 30 major cities in Europe on environmental sustainability. The study evaluated and scored the 30 cities in eight categories: CO2 emissions, energy, buildings, transportation, water, air quality, waste and land use, and environmental governance.

1. Copenhagen, Denmark
2. Stockholm, Sweden
3. Oslo, Norway
4. Vienna, Austria
5. Amsterdam, the Netherlands
6. Zurich, Switzerland
7. Helsinki, Finland
8. Berlin, Germany
9. Brussels, Belgium
10. Paris, France
11. London, United Kingdom
12. Madrid, Spain
13. Vilnius, Lithuania
14. Rome, Italy
15. Riga, Latvia
16. Warsaw, Poland
17. Budapest, Hungary
18. Lisbon, Portugal
19. Ljubljana, Slovenia
20. Bratislava, Slovakia
21. Dublin, Ireland
22. Athens, Greece
23. Tallinn, Estonia
24. Prague, Czech Republic
25. Istanbul, Turkey
26. Zagreb, Croatia
27. Belgrade, Serbia
28. Bucharest, Romania
29. Sofia, Bulgaria
30. Kiev, Ukraine

Source:
www.siemens.com/entry/cc/en/urbanization.htm?section=green_index