The aim of this paper is to review three interlinked aspects of Zero Energy (or Emissions) Buildings (ZEB): definitions, government policies and construction activity. It is critical to understand the current status of these three aspects in order to advance the ZEB concept. In broad terms, a ZEB can be described as a residential or commercial building with greatly reduced energy needs and/or carbon emissions, achieved through efficiency gains, such that the balance of energy needs can be supplied by renewable energy. The paper explores how leading countries have defined and are implementing the concept of ZEBs. Although the term ZEB can be used for both commercial and residential buildings, the paper is limited to the latter since this sector produces the greatest amount of emissions. Case studies are used to illustrate the current level of understanding in various countries. The paper concludes that although the term ZEB has been used for some time, there is still no globally-agreed definition or pathway to it. In addition, construction progress is still limited to demonstration projects located in or driven by countries which have already established ZEB policies or a tradition in low energy buildings. (C) 2013 Elsevier Ltd. All rights reserved.