**4. Discussion**

omies of scale.

**4. Discussion**  Our analysis results reveal that NORCs have developed rapidly over the 10-year period in the greater Brisbane region. The cluster of older population may generate both positive and negative impacts on active ageing. Firstly, in NORCs, service providers and Our analysis results reveal that NORCs have developed rapidly over the 10-year period in the greater Brisbane region. The cluster of older population may generate both positive and negative impacts on active ageing. Firstly, in NORCs, service providers

and multilevel collaborations may serve the older people more efficiently because of the spatially proximate locations for NORC residents living within a reachable range. It is a great opportunity for the government to provide home and community care in NORCs where the older people can enjoy professional care with comparatively low cost due to the economies of scale.

According to the Queensland Department of Communities, Housing and Digital Economy [35], the distribution of retirement villages in the greater Brisbane area is highly consistent with the distribution of older people, where the areas with high density of older residents have one or more retirement villages located around them. This implies that the retirement village developers have realised the advantage of the economic scales brought by the concentration of the older population. Similarly, one or more nursing homes can also be found in these popular areas with older people. NORC supportive service programmes as the solution of ageing-in-place provide the older people with another choice of ageing, which is different from the retirement village or nursing home, and the NORC participants can enjoy some of the services that the institutional care system could not provide, such as exercise and dance classes, trips and cultural events [36]. For the government, NORC programmes play a positive role in reducing the pressure of resource scarcity in the healthcare system [37]. However, it must be clarified that NORCs are different from NORC Service Support Programmes where multilevel collaborations, services and supports are provided to those NORCs with a high proportion of older people. Governments should provide NORC service support programmes to existing NORCs, with the ultimate purpose of providing an age-friendly urban environment to facilitate older Australians' ageing-in-place.

Nevertheless, neither academic research nor government policies recognise this housing option for older Australians. Although the Advisory Taskforce on Residential Transition for Ageing Queenslanders [38] recommended that the Queensland Government and the local governments provide incentives for the development of NORCs as one of the diverse age-friendly housing solutions, no relevant initiatives are available to date, most likely as NORCs do not fit the definition of a retirement community. However, NORCs present a huge opportunity for governments because supporting ageing-in-place can ultimately result in significant public expenditure savings, particularly given the fiscal demands of institutional aged care and healthcare.

In addition, a high density of older population may lead to diverse social networks in later life, which are related to more positive outcomes, including better cognitive functioning [39], lower levels of depressive symptomatology [40], better outcomes in serious physical illnesses [41], reduced likelihood of loneliness and anxiety and increased likelihood of happiness [42]. Studies have found that in maintaining a positive attitude and preventing depression, the existence of a network of friends is as important as, or even more important than, the existence of family members [43]. The Robert Woods Johnson Foundation also emphasises that communities that provide social services and material support have a positive impact on the health of their residents [44]. Moreover, Cornwell, Laumann [45] found that an older adult's larger socialisation network of friends and the frequency of that socialisation positively impact their longevity. However, it should also be noted that while ageing-in-place and ageing-in-community may have the advantages of familiarity and maintaining one's connections, it may also set older adults up for social isolation, particularly if they have limited mobility or access to other people. Social isolation and loneliness have been shown to have negative effects on health and well-being [46].

The temporal distribution of NORCs shows that the formation of NORCs closely aligns with spatial distributions of older population, which could be caused by the in-migration (move into a certain area for permanent living inside or outside the state), out-migration (move out of a certain area to a more suitable place for permanent living) and ageing of existing populations [47]. The increase of high-high clusters and hotspots along the coastal areas, where most of the NORCs are located, might be very likely due to the in-migration of older household members (65+), given that many Australians would like to live in an environment with seaside scenery, convenient seacoast facilities for activities and extending social networks. These people are known colloquially as 'sea-changers' [48].

Likewise, some of the rural residential suburbs and their neighbouring suburbs, such as Esk, Laidley, Boonah and Beaudesert, became ageing hotspots after a 10-year change of demographic mainly because of the out-migration of youth and tree-change in-migration of older people. The proportion of local young generations leaving their rural homelands was high—more than half of the cohort population in some cases [49]. Meanwhile, tree-change as a relatively nascent migration trend of urban residents moving towards inland regional areas of Australia becomes another option for some older people [50]. Clearly, NORCs in rural areas have the great potential to accommodate 'tree-changers', even though current facilities and services can be sparsely located/provided in these areas.

Compared with the increase of the above-mentioned hotspots for older people, the increase of coldspots in the inner city areas are mainly due to young people moving in for job opportunities, along with older people choosing out-migration for retirement [51]. On the contrary, the decrease of low-low clusters in inland areas, caused by the increasing proportion of older population, is mainly due to the natural ageing and younger generations moving out for job opportunities in capital cities or regional centres. Currently, how to better support older people who prefer to remain at home and independent in inland areas can be a challenge for the Australian society.

Understanding the distribution of hot and coldspots associated with NORCs may be useful in guiding governments in resource allocation and optimising investment to promote financial efficiency. As NORCs are clustered in the same hotspot areas, collaborations between industry and local governments across different NORCs, such as sharing the existing infrastructure and services (e.g., transportation and healthcare), will have the great potential to maximise their value to older people due to the increased economic scale. Since NORCs are based on the existing resources of the community, they may become a supplementary part of the local service delivery system. NORCs have become an opportunity to develop and/or strengthen community partnerships to improve how the community responds to the changing needs of residents as they age-in-place [11].

The growth of NORCs in the greater Brisbane region aligns with the phenomenon of population ageing not only in Australia but also in all developed countries. Today, more than 530 cities and communities from 37 countries are participating in the WHO's Global Network of Age-Friendly Cities and Communities; however, government structures are often isolated and lack flexibility to formulate and implement effective age-friendly programmes covering multiple disciplines. Working with local NGOs, citizen groups, service providers and other private sector entities, NORC supportive service programmes will enable local governments to integrate the vision of the age-friendly programme with the interests of older people, coordinate stakeholder priorities and leverage existing resources. With the identification of NORCs and their formation patterns, researchers, communities and local governments can collaborate to understand the local history, economic activities and experience of older residents in those NORCs to enrich policy planning. As the most popular interstate destination for people aged 65+ years (with 31% of interstate arrivals in 2015) [52], Queensland has launched the programme Queensland: An Age-friendly Community since 2016, aiming to ensure older people are free from age-related barriers that prevent community participation. The findings of this study provide a valuable data support this programme.
