The recast of the Directive on Energy Performance of Buildings defined all new buildings will be nearly zero-energy buildings by the end of 2020. However, the transformation of the EU’s building stock will not be completed until well after 2020 and this target can only constitute an intermediate step. The renovation of existing buildings stock offers significant potential for both cost-effective CO2 emissions mitigation and substantial energy consumption reduction. Therefore energy efficiency can be seen as Europe’s biggest energy resource. The cost optimal methodology may be a useful tool able to identify the more appropriate retrofit measures in order to launch the renovation of the existing building stock on a large scale.



















