In recent years, cities globally have focused on reducing their environmental impact while also seeking to catalyse social sustainability [13]. Many cities, particularly in Australia and the United States, have instigated policies to consolidate urban footprints through the development of medium- and high-density housing in inner urban areas to achieve this goal [14,15,16]. Some literature argues that social aspects have been largely ignored in the way housing policy is developed [17,18], while others highlight that governments have tried unsuccessfully to integrate social sustainability into housing policy [19,20]. One of the key vehicles governments have utilised to address social sustainability in housing is pursuing an affordability agenda based on the development of periurban areas [15]. There is, however, growing recognition in the literature of the significant strain this development places on infrastructure [15,21] and its impact on health and well-being [22,23,24,25,26].

One of these social challenges is ageing. The global population is ageing at an unprecedented rate, with current estimates suggesting 21.1% of the global population will be aged 60 years or over by 2050 [27]. In Australia, this figure is estimated to be 22% by 2057 and reach 25% by 2097 [28]. This rapid growth brings significant challenges to the provision of appropriate housing and urban environments for the older demographic. Higher-density housing has shown a positive impact on the health and well-being of older people, but questions remain as to whether apartment living is adequately satisfying their physical needs [29]. Although traditionally overlooked in housing policy development [30], housing people with disabilities such as movement difficulties has become another challenge to be addressed in Australia since the introduction of the National Disability Insurance Scheme (NDIS) in 2013. Accommodation options for people with disabilities have typically been limited to family support, institutionalisation, social housing, or supplies from the private rental market [30,31,32,33]. The NDIS, however, provides people with disabilities significant financial resources to pursue new housing opportunities [34,35]. Under the above context, a number of new approaches have emerged for the development of housing, from the broader guidelines as to how cities should be developed [36,37,38] to specific housing models through collaborative planning and community development, such as those seen in cohousing [39,40] and to industry-focused guidelines such as those of designing for people with physical disabilities [41,42].

Mixed-use developments are primarily known as a response to the detrimental impact of urban sprawling, such as car dependency, traffic congestion, and air pollution [6], while also contributing to financial viability by diversifying the assets within one specific unit or area [43]. Mixed-use housing developments, by combining residential and a diverse range of nonresidential spaces under one (often vertical) structure, can perform a critical role in mitigating social challenges across multiple scales [44,45]. Such agglomerations, particularly in high-rise developments, are associated with positive impacts such as providing social cohesion [46], a sense of community [47,48], social support [46,49], social interaction [50,51], and social well-being and mental health [52]. These potentials are created by bringing the range of amenities and services together, which are especially beneficial to vulnerable or disadvantaged groups such as older people and people with physical disabilities, leading to enhanced safety and increased movement independence [6]. Although mixed-use housing developments have gained growing interest in the literature, practical examples in the sector are very scarce. An example of such a structure is Kampung Admiralty (https://architectureau.com/articles/kampung-admiralty, accessed on 12 April 2023) in Singapore, which offers a community hub in the form of an integrated building function designed to meet the needs of a variety of social groups, especially older people. The amenities and different functions embedded in the building allow them to be socially and physically independent and provide opportunities for leisure, fitness, and other voluntary activities. Another similar initiative in terms of design and functions is Inspir Carnegie Hill (https://handelarchitects.com/project/inspir-manhattan, accessed on 12 April 2023), a high-rise building in the US for housing and supporting older people and people with movement difficulties.

In this paper, social challenges for housing developments in Australia have been used as a basis to identify a suitable case study for the research investigation. U city, being the only vertical mixed-use housing development of its kind and scale in the country, provides us with unique access to a multifaceted network of stakeholders and organisations involved during its development and construction. Compared to conventional single-use projects, the collaborative processes in mixed-use housing projects are much more complex, and this heightened level of complexity could be better facilitated through digital collaboration.

As building projects become increasingly complex, collaborative practices are becoming increasingly important in the building and construction industry [11,13] as they involve large and diverse project teams, including both professional stakeholders and end-users [53]. Despite this important role, there is less consensus in the literature on the definition of collaboration. Studies also use alternative terms for collaboration in the context of construction research and practice, such as partnership [54], team integration [55], etc. Collaboration is suggested to be a key enabler for addressing the fragmentations in housing construction [11,56], as it ensures the successful delivery of a complex building project entwined with highly effective coordination among the stakeholders across the entire value chain.

Groundwork of defining and understanding collaboration in the building and construction industry has been conducted through comprehensive empirical and theoretical developments. Earlier research defines collaboration as an inter-organisational relationship that is driven by a shared vision between all agents with shared responsibilities, risks, and rewards [57]. Schöttle and Haghsheno [57] argue in order for a new and collaborative project culture to be established, it needs to be based upon trust and transparency, as well as mutual problem-solving through interactive processes. In another closely related work, Xue and Shen [58] define collaboration in the architecture, engineering, and construction (AEC) context to be shaped through human behaviours that are highly dependent on the participants’ perceptions of the shared value. In this definition, collaboration is sustained through a strong organisational culture and long-term relationships between team members, with a great emphasis on relational contracting in adverbial conflict resolution.

As the whole AEC industry is significantly influenced by digitalisation, industrialisation, and mechanisation, the effects of their resulting changes in collaboration need to be explored in relation to both the inner- and inter-organisational relationships as to how their collaboration and coordination will benefit from these transitions. In this context, digital collaboration is a key focus. Digital collaboration platforms such as web-based project management applications and network technologies have been extensively studied in the context of construction management for planning and coordination [59,60]. Although such digital platforms are effective for the exchange of project information among different participants, their common applications are limited to scheduling and workflow management suitable for specific stages such as procurement [59], and data being exchanged are mainly around 2D drawings and documents [61]. The integration or inclusion of these earlier tools in the more recent building information modelling (BIM) platforms has been effective in supporting the collaboration of the project team across different design and construction stages. The BIM approach to digital collaboration integrates structured, multidisciplinary data across a building’s entire lifecycle—from planning and design to construction and operation—based on a 3D digital model of the building or infrastructure, which can be further enhanced with machine intelligence and cloud computing. BIM technologies have been found to be able to significantly improve collaborative processes, particularly in large-scale and complex building and construction projects [53,62,63,64], and they are increasingly adopted as the preferred method for collaboration in the industry [65,66].

It is, therefore, logical to predict that digital platforms such as BIM that can facilitate collaboration and data exchange throughout the whole project lifecycle would be equally effective in providing an enhanced collaboration environment for the delivery of complex housing developments addressing a wide range of social, environmental, and economic needs. With further technological advancement and careful implementation, such platforms would also be able to support the increasingly complex and diverse project teams, including both specialists and end-users relevant to those social challenges in housing, as discussed in the above section. However, in the current literature, while there are examples of collaborative processes associated with similarly intricate projects like specialised healthcare developments [53,67,68], there is less research about collaborative practices in complex residentials, especially mixed-use housing developments.

One of the key challenges that has emerged in the adoption of digital collaboration in construction is understanding the ways in which the necessary processes differ from the past ‘status-quo’ models of construction procurement and management [11]. To this end, London and Pablo [11] present a collaborative practice (CP) model that can be used to understand the processes within the building and construction industry. This model can be used as a way of understanding the network-based relationships associated with construction projects when embarking upon transformational changes in the housing sector. Our study builds upon the CP model, which was developed through five comprehensive case studies from small and medium enterprises (SMEs) active in the off-site manufacturing (OSM) housing sector in Australia. The model defines nine key elements that are essential in facilitating the adoption of new technologies and industry-wide transformational changes, as well as the accompanying collaborative practices amongst various stakeholders in complex organisational networks that are required to instigate and sustain the changes. One such element is “Leadership,” which involves creating an environment conducive to change through skilful leadership. “Shared goals” represent another crucial aspect, encompassing the envisioning of compelling project objectives that address specific challenges.

The CP model also emphasises the importance of assembling a team with the appropriate “Expertise”—individuals possessing the necessary skills to contribute meaningfully to the project’s success. Addressing change is another significant dimension, with the model advocating for strategies to manage change and handle potential resistance during the project’s lifecycle.

“Investment” in resources is highlighted as an essential factor, suggesting the conscious allocation of resources to attract, retain, and acquire assets vital to the project’s advancement. “Shared space” is recognised for its role in nurturing productive face-to-face interactions, while “Problem-solving” is underscored for its emphasis on pursuing participative, adaptable, and forward-looking solutions.

The CP model also underscores the significance of “Organizing mechanisms,” emphasising the need to formalise team characteristics to sustain effective work patterns. Finally, “Technical standards” are deemed crucial for documenting and disseminating precise and accurate information, thus contributing to the overall success of collaborative endeavours.

Although the original CP model was developed based on case studies of OSM supply chains in SMEs, the generalisation and extension of the model have been shown to be applicable to the building and construction industry in general by adapting the meaningful relationships between those nine elements as they occur in other specific contexts [8]. We take this model as the basis of a theoretical framework for the data analyses and interpretation narratives because of its effectiveness in unfolding the multifaceted aspects of collaboration. Additionally, our case study and the original case studies upon which the CP model was developed share a similar level of complexity in collaboration, where they both consist of multiple networks of collaborators and organisations working together across different stages of the project. When necessary, adaptation is possible because many of the core structures and processes in these case studies are still equivalent and are applicable to a larger context [69]. In doing so, we aim to enhance the original CP model by extending its application and detailing the interrelationships between those elements as they occur in the new context, focusing on digital collaboration. This will also further improve the transferability of the model.