Report vol 2 - KEP energy

 

The Zero Energy Building (ZEB) concept, that is a building having zero energy impact, has been confined until now in the research field, and applied only in experimental contexts. Recently the concept has reached a wider interest as a result of the EPBD recast Directive publication. The Directive has established the ZEB, adapted in the "nearly" version, as energy performance target for new buildings starting from 2020. Therefore it is necessary and timely an in-depth understanding of the nearly Zero Energy Building (nZEB) concept, through an interpretation able to relate its meaning to the overall European set of technical standards.

The report starts from a review of the main interpretation of a Zero Energy Building found in literature, and consequently extracts the nZEB and NZEB definition. These definitions are set on the basis of energy balances, in compliance with the EPBD recast Directive and the system of technical standards developed from the European Committee for Standardization (CEN). Two fundamental methodological aspects are analyzed, in order to bring consistency and effectiveness to the building energy performance assessment. The first one refer to the system boundary, on which are accounted the energy fluxes, distinguishing between "physical boundary" and "energy boundary", and expliciting the weight factors of the energy carriers that cross it. The second refer to the energy uses from which originates the final energy demand and the problems of their assessment, considering different modalities of accounting, and pointing towards a standardization of the calculation criteria.