**5. Conclusions**

To support older Australians' preference for ageing-in-place, it is essential to provide a smart, sustainable and age-friendly urban environment [53,54].This study aimed to understand the distribution and formation of NORCs with temporal changes for the first time in Australia. As emerging age-friendly communisis, NORCs evolved rapidly in the greater Brisbane region, accommodating 7.2% of the older members of households, although accounting only for 1.7% (92) of the total census units in 2016. In addition, NORCs

were not developed randomly, but are mainly clustered or co-located along the Brisbane River and the coastline areas, which attract an increasing number of older people moving into these areas for retirement living.

This study provides both knowledge and practical implications for NORCs and urban development. First, the spatial analytic approach made the geographical reference data more accessible and comprehensive. It visualised and described the distribution patterns, temporal trends and geographic locations of NORCs at the city level. Second, a multilevel cooperation among local governments, industries and agencies can be developed to provide better services and urban environment for the older population in these areas. Finally, this research offers an approach to data visualisation to interpret the temporal and spatial distribution of NORCs.

This study has some limitations. First, although the geographical factors affect the clusters or outliers of NORCs, the development of NORCs may be driven by multiple factors, such as built environment, natural scenery, walkability, accessibility and health and social services, the information of which was not available in the Census data. The second limitation in the spatial analysis is the mutative unit, which was modified from CD in 2006 to SA1 in 2011 and 2016. Different units of analysis may change the findings, even though the changing may follow the life pattern of the local population. Thirdly, the distribution of nursing homes and aged care facilities may likely affect the growth and development of NORCs, whose pattern of influence needs to be explored in future studies. Fourthly, among the census units with a high proportion of older household members (65+), some of them (accounting for less than 0.5% of the total census units, and many located in national parks or remote usual areas) have a small number of total household members (less than 200). As a result, the proportion of senior residents in these census units can be easily affected by the relocations of older people, even in a very small number. Therefore, whether these census units can be identified as NORCs needs to be further investigated according to the actual living environment and neighbourhood relationship.

The occurrence mechanisms of NORCs requires further investigation in the future. An ageing policy and related services regarding NORCs may be promoted to provide better ageing-in-place for older Australians.

**Author Contributions:** Conceptualisation, B.X.; methodology, J.E.; formal analysis, J.E.; writing original draft preparation, B.X. and J.E.; writing—review and editing, L.B. and T.Y. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Ethical review and approval were waived for this study, due to the data set this search using was from the Australian Bureau of Statistics Census Data which is the open resources database can be visited publicly.

**Informed Consent Statement:** Patient consent was waived due to no specific patient information was used in this study because the data set this search using was from the Australian Bureau of Statistics Census Data which is the open resources database can be visited publicly.

**Data Availability Statement:** Data are available in a publicly accessible repository that does not issue DOIs. Publicly available datasets were analysed in this study. These data can be found here: [www.abs.gov.au] accessed on 5 July 2021, Census TableBuilder, 2006, 2011 and 2016 Census-Counting Persons, Place of Usual Residence.

**Conflicts of Interest:** The authors declare no conflict of interest.
