Standardization of green building technologies: Nearly Zero-Energy Buildings (nZEB)

European legislation EPBD [1] (Energy Performance of Buildings Directive) makes nearly Zero-Energy Buildings (nZEBs) a standard by 2020. The technology is already available and proven; however, the large-scale uptake of nZEB construction and renovation will be a big challenge for all market actors and stakeholders involved. A substantial gap in reliable data on current market activities makes it difficult for policy-makers to evaluate the success of their policies and measures [2]. As concrete numeric thresholds or ranges are not defined in the EPBD, these requirements let a lot of space for own interpretation and thus allow Member States (MSs) to define their nZEB in a very flexible way taking into account their country specific climate conditions, primary energy factors, ambition levels, calculation methodologies and building traditions. This is also the main reason why existing nZEB definitions differ significantly from country to country. It is thus a challenging task to find a common denominator for defining an nZEB on a European scale [1,2].