Criteria for Definition of Net Zero Energy Buildings

Abstract

The idea of a Net Zero Energy Building (Net ZEB) is understood conceptually, as it is understood that the way a Net ZEB is defined affects significantly the way it is designed in order to achieve the goal. However, little agreement exists on a common definition; the term is used commercially without a clear understanding and countries are enacting policies and national targets based on the concept without a clear definition in place. This paper presents a harmonised framework for describing the relevant characteristics of Net ZEBs in a series of criteria. Evaluation of the criteria and selection of the related options becomes a methodology for elaborating sound Net ZEB definitions in a formal, systematic and comprehensive way, creating the basis for legislations and action plans to effectively achieve the political targets. The common denominator for the different possible Net ZEB definitions in the harmonised framework is the balance between delivered and feed-in energy and associated credits. Additionally, other indicators than the mere balance over a period of time may be given in order to add qualified information on the overall “goodness of design” of a Net ZEB. Finally, the monitoring procedure is considered as an integral part of the definition.