Since 1998 EcoEnergy actively and closely work with the European association Energy Cities and since 2003 is its regular member. The cooperation between EcoEnergy and Energy Cities ensures access to the accumulated experience of the European municipalities. 

Both associations work together on several European projects as MODEL and RUSE and participate in campaigns and initiatives in energy efficiency field.

In 2006 a Memorandum between Energy Cities and EcoEnergy has been signed for collective participation of the Bulgarian network in Display campaign which aims at introducing the municipalities with the practicies for displaying energy labels of the buildings.

Energy Cities promotes and encourages:

• Establishment of national networks of energy cities with qualified staff which can give technical and other support to the municipalities (in close cooperation with the national associations of municipalities and national agencies, where it is possible).
  
  
• Gathering of the national networks of energy cities in "regional" ones.