Energy efficiency in buildings will play a major role in responding to climate change and energy issues, if we are able to trigger large scale actions involving EU, all Member States and their regional and local authorities. The concept of “Geo-clusters” is highly relevant, being virtual trans-national areas where strong similarities are found (i.e. climate, culture and behaviour, construction typologies, economy, energy price and policies and gross domestic product, to name a few). In this framework, it is clear that the geo-cluster map will not be based on fixed geographic regions, but is to be considered as a multi-dimensional and dynamic tool.Our goal is to locate similarities across enlarged EU by combining single or multiple parameters and indicators organised in homogeneous layers and sub-layers. As a pure example, we may consider a Technological layer (i.e. building typologies, technologies, ..), a Context layer (i.e. climatic conditions, ...), a Socio-economic layer (i.e. macroeconomic indicators, behavioural aspects,…), a Political-strategic layer (i.e. standards and regulations, energy policies, ..).There are however a number of barriers that are due to scattered knowledge, specific needs, failure modes and bottlenecks, as well as the weakness and threats experienced by running clusters dealing with energy efficiency in the built environment across EU, requiring a EU coordination action centred on a two-fold approach:1. Structuring and correlating the existing knowledge and information available at broader public level on EU, National and local basis. Once descriptors have been identified, a correlation methodology will then be developed to associate the different data layers and create multi-dimensional maps.2. Validation through two pilot clusters, performing an in-depth analysis and validation of the overall approach and methodology focusing on the two pilot clusters Mediterranean arc and Western Central and Northern West EU.