Zero emission neighbourhoods and positive energy districts – A state-of-the-art review

•Growing interest in climate friendly neighbourhood research.•Most covered topic of reviewed studies was the energy system.•In total, 35 different terminologies were used for climate friendly neighbourhoods.•Lack of clear definitions, both in scientific literature and international research projects. Urban areas are critical in accomplishing the clean energy transition and meeting the climate goals in the Paris Agreement. The first part of this paper presents a systematic review of scientific publications on zero emission neighbourhoods, positive energy districts and similar concepts of climate friendly neighbourhoods (CFN). The second lists a selection of CFN definitions of public initiatives and research projects. The aim is to identify focus areas, research gaps and future research possibilities. In the systematic review, 144 papers were categorised and analysed according to their concept terminology, topic, location, used methodology, publication type, year, citations and keywords. The results document the growing but thematically and geographically unbalanced attention given to CFNs. Most research (31.9 %) was connected to the energy system, whereas social aspects (4.2 %) and the microclimate (3.5 %) were least researched. Within the analysed literature, 35 different terminologies for CFNs were used which highlights the lack of clear definitions and arbitrary use of terminologies. This issue is also reflected in the significant differences of CFN definitions from public initiatives and research projects. This article stresses the need for clear, comprehensible and structured definitions, including KPIs, system boundaries, as well as definitions of the spatial scales.