Residential properties with co-living structures have gained popularity due to the allure of shared operating costs and access to high-quality amenities (such as swimming pools, jacuzzi, saunas, tennis courts, gardens, and restaurants) [1]. For individual residential properties, operating and maintenance costs may be prohibitively high and access to amenities may be limited. However, co-living residential spaces with efficient building maintenance and management have the appeal of lower operating costs. Consequently, the concept of sharing costs among residents has been embraced by many homebuyers, leading to the emergence of housing estates, especially in densely populated cities like Hong Kong [2]. These large-scale housing estates, characterized by high-rise residential towers, also typically offer ample open spaces and amenities, with some even featuring clubhouses resembling those found in hotels. Employing professional property management with robust security systems and efficient maintenance services further justifies the appeal of such co-living housing arrangements [3]. Nevertheless, the advantages of co-living in housing estates may be outweighed by their inconveniences. For instance, excessive congestion or poor management could induce significant costs for co-living residential properties [4].

The concept of sharing spaces and facilities in a housing estate can be viewed as an alternative form of co-living, as co-living is defined as housing arrangements in which individuals have a private self-contained housing space (a house, a flat, or a bedroom) but share a range of communal facilities with others [5]. Co-living has emerged as a new way of urban living that emphasizes community and convenience [5]. However, most previous studies on co-living spaces have focused on small-scale arrangements, such as room sharing within a house ^[3][6][3,6].

2. Co-Living at Its Best—An Empirical Study of Economies of Scale, Building Age, and Amenities of Housing Estates in Hong Kong

Co-living arrangements in residential properties have garnered significant attention in recent years as a response to the escalating housing rents in major cities ^[3][7][8][9][3,7,8,9]. Many individuals turn to co-living as a means to attain homeownership in a more delayed fashion or as a viable alternative when traditional homeownership seems unattainable ^[10][11][10,11]. Co-living refers to a living arrangement where individuals, sometimes unrelated individuals, or families, live together in a shared space, typically in a residential property or community. This arrangement involves sharing common areas, amenities, and sometimes even resources such as kitchens, living rooms, and bathrooms while also maintaining private living spaces like bedrooms [3]. Co-living can take various forms, including short-term rental markets and small-scale home sharing facilitated by platforms like Airbnb, which promote sharing economies and sustainability ^[12][13][12,13]. The concept of co-living often emphasizes community interaction, socialization, and the sharing of responsibilities and resources among residents ^[14][15][14,15]. This study argues that co-living has also been a prevalent practice in many housing estates within high-density cities. These housing estates can be viewed as co-living arrangements, where homeowners come together to share common spaces and estate facilities available within the estates [16]. The management of these common facilities becomes crucial. Facility management, which involves the coordination of space, infrastructure, people, and organization, plays a significant role in the administration, day-to-day operations, and shaping organizational culture ^{[17][18][19][20]}[17,18,19,20]. The emergence of housing estates resembling hotels can be attributed to residents’ desire to enjoy the comforts and conveniences typically associated with hotel accommodations. These housing estates offer a wide range of clubhouse amenities, contributing to a luxurious living experience and enhancing the perceived value of the properties [21]. Agents will also present home buyers with the value of these amenities [22]. Furthermore, efficient building maintenance and management services ensure a hassle-free lifestyle for residents ^[23][24][23,24]. One of the primary motivations for residents to opt for hotel-like housing estates is the opportunity to share costs associated with the provisions and the upkeep of facilities. Maintaining and managing these amenities individually would be financially burdensome for homeowners, making the shared cost model an attractive solution [25]. This shared cost model allows residents to access superior amenities while mitigating the financial strain, leading to the popularity of housing estates, particularly in high-density cities like Hong Kong. However, it is important to acknowledge that there are drawbacks to co-living arrangements, one of which is the potential loss of privacy ^[26][27][26,27]. Privacy is considered a crucial element of individuals’ quality of life, and the absence of privacy in co-living situations can have a negative impact on residents [27]. It is worth noting, however, that the social interactions and support provided within co-living environments may serve as a potential counterbalance to the concerns related to privacy ^[28][29][28,29]. The service quality gap and the level of consumer satisfaction are influenced by the discrepancy between consumers’ perceptions and expectations [30]. When there is an increased number of residents involved, the upkeep and maintenance of different aspects become more challenging, which can impact resident satisfaction ^[31][32][33][31,32,33]. In a study conducted by Au-Yong [34], the factors contributing to the breakdown of lift systems in low-cost, high-rise residential buildings were examined. The findings revealed that ineffective maintenance significantly affected resident satisfaction, highlighting the importance of regular and effective facility maintenance in high-density residential buildings. Olanrele and Thontteh conducted a study that assessed and compared the delivery of facilities management services in public high-rise residential buildings in Nigeria. Their findings indicated that the availability of services and resident satisfaction varied among different estates, suggesting that the quality of services and the social class of residents can influence satisfaction levels [30]. Mokhsin et al. developed a mobile application aimed at improving communication and information sharing for high-rise residential management [35]. This innovative approach has the potential to reduce costs and enhance resident satisfaction. The study highlights the challenges and difficulties faced in enhancing resident satisfaction in high-density residential settings, especially when more residents are involved. Indeed, co-living arrangements can be viewed as exhibiting economies of scale, particularly in terms of cost sharing and resource utilization. By living together and sharing common spaces, amenities, and facilities, residents can benefit from reduced costs per capita. The pooling of resources allows for greater efficiency and economies in terms of maintenance, utilities, and other shared expenses. Moreover, co-living fosters opportunities for collaborative consumption, where residents can collectively purchase and utilize resources more effectively, potentially leading to cost savings and improved resource allocation. However, diseconomies of scale within co-living arrangements are possible. The loss of privacy and potential conflicts arising from shared living spaces can lead to a reduction in overall resident satisfaction. As the number of co-living residents increases, coordination and decision-making processes may become more complex, potentially hindering effective management and decision making. Furthermore, the maintenance and management of facilities can become challenging with a larger number of residents, potentially decreasing service quality and resident satisfaction. Therefore, the extent to which the advantages outweigh the disadvantages in co-living arrangements depends on how to implement effective governance structures, communication channels, and maintenance protocols that can help address challenges associated with increased resident numbers and ensure a positive co-living experience. The success of co-living all depends on striking a balance between the benefits of scale and the effective management of potential drawbacks, thus optimizing the overall experience for residents.