New Roadmap toward Social Sustainability, from Physical Structures to Perceived Spaces

Abstract

This article explores the intricate relationship between urban density and social sustainability by examining the impacts of both physical and perceived density on key social sustainability criteria. Physical density is defined by measurable attributes such as building height, spacing, and population. Perceived density, on the other hand, is shaped by residents’ subjective experiences influenced by visual, functional, social, and spatial factors. This study analyzes data from the literature using the thematic analysis method. It reveals that social sustainability can be negatively affected by increased density, depending on how residents perceive high density. Key factors such as building design, green spaces, availability of amenities, and street layout are crucial in shaping residents’ perceptions of density. These perceptions, in turn, affect inclusivity, community engagement, quality of life, cultural diversity, and social cohesion within urban areas. The research highlights the importance of integrating green spaces, public areas, and community amenities to mitigate negative perceptions of density and enhance overall quality of life. The findings suggest that achieving social sustainability requires a nuanced understanding of both physical and perceived density. This paper provides a comprehensive framework for understanding these complex relationships and offers valuable insights for creating socially sustainable urban environments.

1. Introduction

As urbanization continues to accelerate, the relationship between urban density and sustainability has become increasingly important for city planners and policymakers. Urban density, defined by measurable factors such as population numbers, building spacing, and the design of urban spaces, plays a critical role in shaping the sustainability of urban environments across environmental, economic, and social dimensions.

Urban density has significant environmental and economic implications. Higher urban density can lead to reduced land consumption, more efficient infrastructure use, and lower per capita energy consumption due to the proximity of services and amenities. Additionally, dense urban areas support sustainable transportation systems, reducing reliance on private vehicles and lowering greenhouse gas emissions [1,2]. Economically, high-density areas can enhance productivity by concentrating businesses and services, fostering innovation, and creating vibrant, walkable communities [3]. These benefits underscore the multifaceted importance of urban density in sustainable development. However, urban density is not merely about the number of people per area; it also encompasses the design of buildings, the availability of green spaces, and the layout of streets, all of which significantly impact the quality of urban life [4,5,6]. These elements influence not only the physical aspects of urban environments but also residents’ perceptions of their surroundings, thereby affecting social sustainability.

Despite the benefits, urban density presents challenges that need to be carefully managed to ensure sustainability. These challenges include potential overcrowding, increased pressure on public services and infrastructure, reduced privacy and personal space, and environmental degradation if green spaces and sustainable building practices are not prioritized [7,8]. Addressing these challenges requires thoughtful urban planning that balances density with livability, ensuring that urban environments remain inclusive, equitable, and supportive of a high quality of life.

Social sustainability is a critical component of urban sustainability. It focuses on promoting social cohesion, inclusivity, and quality of life for all residents. High-density environments can either enhance or undermine social sustainability, depending on how they are designed and managed. Well-designed public spaces, mixed-use developments, and accessible amenities can foster community engagement and cultural diversity, while poor management of density can lead to social fragmentation and reduced quality of life [9,10,11]. Therefore, understanding the impact of urban density on social sustainability is crucial for creating resilient and equitable urban communities. Although substantial research has been conducted on the environmental and economic benefits of urban density, there is a notable gap in understanding its impact on social sustainability. Most studies have focused on how high-density environments reduce land consumption and support sustainable transportation [1,2]. However, fewer have explored how these environments can lead to social challenges, such as reduced privacy, increased stress on public services, and potential social fragmentation [7,8]. This study aims to bridge this gap by providing a comprehensive framework that integrates both physical and perceived aspects of density to better understand their combined impact on social sustainability.

The specific objectives of this study (examining building design, green spaces, the availability of amenities, and street layout) were selected based on their critical roles in shaping both the physical and perceived aspects of urban density. These factors were chosen due to their direct influence on how residents experience and interact with their environment, which, in turn, affects social sustainability. Building design determines the extent of privacy and personal space available to residents, while green spaces provide essential recreational opportunities and aesthetic relief. The availability of amenities and the layout of streets are key to ensuring accessibility and fostering vibrant, socially cohesive communities. These criteria were identified through a comprehensive review of the literature and are integral to understanding the multifaceted impact of urban density on social sustainability [4,9,12].

This study uniquely contributes to the existing body of knowledge by integrating both physical and perceived aspects of density into a comprehensive framework that addresses their combined impact on social sustainability. Unlike previous studies, which have often treated these dimensions separately, this research offers a holistic approach that underscores the interdependence of urban design elements and resident perceptions. By emphasizing the importance of nuanced urban planning that considers both measurable and experiential factors, this study provides new insights into creating socially resilient and equitable urban environments.

2. Materials and Methods

This study adopted a qualitative approach to explore the relationship between urban density and social sustainability. The research focused on both physical and perceived density and their impacts on key social sustainability criteria, such as inclusivity, community engagement, quality of life, cultural diversity, and social cohesion.

2.1. Literature Review Process:

A comprehensive literature review was conducted using academic databases, including Google Scholar, JSTOR, and Science Direct. The search utilized specific keywords such as urban density, social sustainability, physical density, perceived density, building design, green spaces, amenities, and street layout. These keywords were chosen based on their relevance to the study’s objectives, aiming to capture a broad spectrum of research on how physical structures and urban layouts influence social sustainability in high-density environments. Initially, approximately 200 references were identified and reviewed based on their titles and abstracts. Articles were selected for further analysis if they met the following criteria: (1) they were published between 1990 and 2024 to include both foundational and recent studies; (2) they directly addressed urban density in the context of social sustainability; and (3) they provided empirical data, theoretical insights, or case studies relevant to the study’s focus. After applying these criteria, 31 articles were selected for detailed analysis. A flow diagram outlining the literature selection process is provided in Figure 1.

2.2. Research Strategy and Data Collection

The research strategy involved systematically reviewing the literature to ensure a comprehensive understanding of the existing knowledge on urban density and social sustainability. This process was informed by recent systematic literature reviews, such as those by Heymans et al. (2019) and Sanei et al. (2022), which provided contemporary frameworks for analyzing urban sustainability through ecological urban planning and the assessment of urban housing sustainability factors [13,14]. These studies highlight the importance of integrating socio-ecological systems and sustainability indicators across various urban contexts, which aligns with the objectives of this research.

2.3. Data Analysis

Data analysis: The selected articles were subjected to thematic analysis to identify key themes, patterns, and gaps in the literature. The thematic analysis involved several steps:

• Familiarization: Engaging deeply with the selected literature to understand the breadth and depth of the content.
• Theme identification: Recognizing significant themes related to physical and perceived density, and their influence on social sustainability.
• Theme development: Developing these themes into coherent categories that reflect the complex interactions between urban density and social sustainability.
• Theme review and refinement: Refining the themes to ensure they accurately represent the data and are aligned with the study’s objectives.
• Integration into framework: Integrating the final themes into a comprehensive framework that informs the study’s conclusions about the relationship between urban density and social sustainability.

Based on the thematic analysis, a conceptual framework was developed to integrate the findings and provide a structured understanding of the relationship between physical and perceived density and social sustainability. This framework includes quantifiable attributes such as building height, spacing, population density, residential density, urban design for physical density, and subjective experiences influenced by visual, functional, social, and spatial factors for perceived density.

3. Literature Review

This article categorized the literature on urban density and social sustainability into three main themes: density and physical structures, resident perception of density, and social sustainability. This section will explore each of these themes in detail, highlighting the perspectives of various researchers and their key findings.

3.1. The Literature on Density and Physical Structures

Many studies that have dealt with density and sustainability focused on the physical and structural aspects of urban areas, such as population density, residential density, the Floor Area Ratio (FAR), and the Building Coverage Ratio (BCR), see Table 1. Newman and Kenworthy (1999) focused on the environmental benefits of high population density. Their research emphasized that high population density can enhance urban efficiency by reducing per capita land consumption and supporting sustainable public transportation systems [1]. This perspective is supported by others such as Ewing and Cervero (2010), who found that higher density reduces vehicle miles traveled, thus lowering greenhouse gas emissions [3]. The recent literature has expanded on these findings; for instance, Smith and Williams (2024) further emphasized the importance of integrating social and environmental perspectives in urban density management, showing that carefully managed density can enhance urban resilience while contributing to sustainability [15]. Additionally, Dupont et al. (2023) explored how urban density affects the provision of health-related ecosystem services, emphasizing the need for green spaces to balance the potential negative impacts of high-density environments [16].

Churchman (1999) critiqued the unmanaged increase in population density, pointing out that it can lead to overcrowding and stress on public services. Churchman pointed out the need to understand the potential social disadvantages of high physical density if it is not managed properly [4]. Similarly, Gifford (2007) and Burdett (2011) highlighted the adverse effects of excessive density on social and mental well-being [17,18]. Forsyth’s study (2003) provided a comprehensive analysis of residential density, arguing that higher residential density can improve the efficiency of infrastructure and service delivery, thereby reducing the urban footprint. However, Forsyth also notes the importance of maintaining a balance to avoid issues such as overcrowding [5]. This view is noted by Jacobs (1961) and Burton (2000), who advocated for a balanced approach to density that maintains livability [2,19]. Li and Zhao (2023) also contributed to this discussion, analyzing the trade-offs between high density and environmental outcomes in various cities, and highlighting the complexities of managing urban density for sustainability [20].

Charou et al. (2015) investigated the implications of the Floor Area Ratio (FAR) and the Building Coverage Ratio (BCR). They suggested that higher FAR values can support urban density by reducing urban sprawl. However, they mention that a high FAR can lead to reduced access to sunlight and ventilation, impacting residents’ quality of life [21]. This note is shared by Ng (2010) and Steemers (2003), who emphasize the importance of environmental quality in high-density areas [22,23]. On the other hand, Haarhoff et al. (2016) focused on the balance between density and the quality of living spaces. They argued that while higher residential density can reduce the urban footprint, it is crucial to ensure that living spaces remain comfortable and private to avoid negative perceptions of overcrowding [24]. Alexander et al. (1977) also stressed the need for design quality in high-density environments to enhance livability [12]. In a similar vein, Wang and Li (2023) explored design strategies for high-density urban environments, focusing on how to maintain livability and avoid the negative impacts of overcrowding [25].

Recent studies continue to build on these findings. For example, Dehghani et al. (2023) examined the relationship between urban density and resilience in an Iranian metropolis; their study underscores that urban resilience cannot be fully understood without accounting for the multiple dimensions of density, such as physical, functional, and social aspects. Specifically, they found that while higher physical density can improve resource efficiency, it is the perceived density that ultimately determines the success of urban resilience strategies. For example, well-designed public spaces and green areas can mitigate the negative effects of high physical density, thereby enhancing both social cohesion and overall urban resilience. This highlights the importance of considering multiple dimensions of density to develop resilient urban environments. Additionally, Abenayake et al. (2023) developed a spatial simulation framework to assess the impact of urban density on surface runoff, underscoring the significance of density management in mitigating environmental risks [7,26]. Lee and Chung (2024) have also examined how urban density impacts resident satisfaction through the use of green spaces and urban trails, providing new insights into how urban design can enhance the quality of life in dense areas [27].

Table 1. The literature on density and physical structures.

Paper Title	Authors	Reference Number	Processing Keywords
Sustainability and Cities: Overcoming Automobile Dependence	Newman and Kenworthy	[1]	urban efficiency, sustainable transportation, social sustainability
The Compact City: Just or Just Compact? A Preliminary Analysis	Burton	[2]	urban form, compact city, quality of life
Travel and the Built Environment: A Meta-Analysis	Ewing and Cervero	[3]	built environment, travel behavior, sustainability
Disentangling the Concept of Density	Churchman	[4]	density conceptualization, urban planning, social cohesion
Measuring Density: Working Definitions for Residential Density and Building Intensity	Forsyth	[5]	residential density, urban design, sustainability
Designing High-Density Cities for Social and Environmental Sustainability	Ng	[22]	high-density urban design, social resilience, environmental quality
The Role of FAR and BCR in Shaping Urban Density and Land Use Efficiency	Charou et al.	[21]	FAR, BCR, land use efficiency, social interaction
Does Higher Density Housing Enhance Livability? Case Studies of Housing Intensification in Auckland	Haarhoff et al.	[24]	housing density, livability, social sustainability
Energy and the City: Density, Buildings, and Transport	Steemers	[23]	energy efficiency, urban resilience, environmental design
Urban Density Resilience and Sustainability: Integrating Social and Environmental Perspectives	Smith and Williams	[15]	urban resilience, density management, social cohesion
The Effects of Urban Density on the Provision of Multiple Health-Related Ecosystem Services	Dupont et al.	[16]	health-related ecosystem services, green spaces, density impact
The Consequences of Living in High-Rise Buildings	Gifford	[17]	high-rise living, mental well-being, social consequences
Living in the Endless City	Burdett	[18]	urban design, social life, urban density
The Death and Life of Great American Cities	Jacobs	[19]	urban planning, community engagement, density management
Urban Density and Environmental Sustainability: A Cross-City Comparative Analysis	Li and Zhao	[20]	environmental sustainability, urban density, cross-city analysis
Urban Form and Social Sustainability: The Role of Density and Housing Type	Bramley and Power	[28]	social sustainability, housing type, urban form
Collaborative Planning: Shaping Places in Fragmented Societies	Healey	[29]	collaborative planning, community engagement, resilience
Urban Sustainability and Resilience: From Theory to Practice	Romero-Lankao et al.	[30]	urban resilience, sustainability, theoretical perspectives
Design for Social Sustainability	Woodcraft et al.	[8]	social sustainability, community design, public spaces
The Image of the City	Lynch	[31]	spatial perception, urban design, quality of life
Livable Streets	Appleyard	[32]	livability, street design, community interaction
Life Between Buildings: Using Public Space	Gehl	[9]	public space, urban life, social interactions
The Social Life of Small Urban Spaces	Whyte	[10]	public spaces, social life, urban density

Table 1. The literature on density and physical structures.

Paper Title	Authors	Reference Number	Processing Keywords
Sustainability and Cities: Overcoming Automobile Dependence	Newman and Kenworthy	[1]	urban efficiency, sustainable transportation, social sustainability
The Compact City: Just or Just Compact? A Preliminary Analysis	Burton	[2]	urban form, compact city, quality of life
Travel and the Built Environment: A Meta-Analysis	Ewing and Cervero	[3]	built environment, travel behavior, sustainability
Disentangling the Concept of Density	Churchman	[4]	density conceptualization, urban planning, social cohesion
Measuring Density: Working Definitions for Residential Density and Building Intensity	Forsyth	[5]	residential density, urban design, sustainability
Designing High-Density Cities for Social and Environmental Sustainability	Ng	[22]	high-density urban design, social resilience, environmental quality
The Role of FAR and BCR in Shaping Urban Density and Land Use Efficiency	Charou et al.	[21]	FAR, BCR, land use efficiency, social interaction
Does Higher Density Housing Enhance Livability? Case Studies of Housing Intensification in Auckland	Haarhoff et al.	[24]	housing density, livability, social sustainability
Energy and the City: Density, Buildings, and Transport	Steemers	[23]	energy efficiency, urban resilience, environmental design
Urban Density Resilience and Sustainability: Integrating Social and Environmental Perspectives	Smith and Williams	[15]	urban resilience, density management, social cohesion
The Effects of Urban Density on the Provision of Multiple Health-Related Ecosystem Services	Dupont et al.	[16]	health-related ecosystem services, green spaces, density impact
The Consequences of Living in High-Rise Buildings	Gifford	[17]	high-rise living, mental well-being, social consequences
Living in the Endless City	Burdett	[18]	urban design, social life, urban density
The Death and Life of Great American Cities	Jacobs	[19]	urban planning, community engagement, density management
Urban Density and Environmental Sustainability: A Cross-City Comparative Analysis	Li and Zhao	[20]	environmental sustainability, urban density, cross-city analysis
Urban Form and Social Sustainability: The Role of Density and Housing Type	Bramley and Power	[28]	social sustainability, housing type, urban form
Collaborative Planning: Shaping Places in Fragmented Societies	Healey	[29]	collaborative planning, community engagement, resilience
Urban Sustainability and Resilience: From Theory to Practice	Romero-Lankao et al.	[30]	urban resilience, sustainability, theoretical perspectives
Design for Social Sustainability	Woodcraft et al.	[8]	social sustainability, community design, public spaces
The Image of the City	Lynch	[31]	spatial perception, urban design, quality of life
Livable Streets	Appleyard	[32]	livability, street design, community interaction
Life Between Buildings: Using Public Space	Gehl	[9]	public space, urban life, social interactions
The Social Life of Small Urban Spaces	Whyte	[10]	public spaces, social life, urban density

3.2. The Literature on Resident Perception of Density

Some studies on density have gone beyond considering it as a matter of numbers divided by area and have focused on the psychological effects and how residents perceive their residential environment, as seen in Table 2. Alexander et al. (1977) studied the visual perception of density, examining how the appearance of an area, including building height and spacing, influences residents’ perceptions of density. They found that areas with taller buildings or closely packed structures may seem denser, impacting mental well-being and satisfaction [12]. Supporting studies by Rapoport (1975) and Appleyard (1981) underscored the significant roles that visual cues, such as building height, spacing, and architectural design, play in shaping perceived density. They found that these visual elements can influence how crowded an area feels to its residents, impacting their overall satisfaction and mental well-being [6,32]. A recent study by Liu et al. (2024) examined how high-density built environments influence emotional perceptions using social media data. Their study found that positive emotions are spatially varied in high-density environments and are influenced by multiple variables such as the open space ratio and the green space ratio [33]. This research underscores the importance of incorporating green spaces and open areas in high-density urban planning to improve residents’ emotional well-being.

Ma et al. (2023) conducted a study using machine learning to analyze street view images, revealing how the visual characteristics of urban streetscapes influence residents’ perceptions of density and urban vitality [34]. Unal Cilek et al. (2024) investigated the impact of public spaces on urban life quality in Adana, Turkey, highlighting how open spaces and recreational areas contribute to residents’ perception of their urban environment [35].

Gehl (2011) focused on the functional perception of density, emphasizing the importance of having a high concentration of amenities, services, and activities within an area. His findings highlight that areas with diverse amenities within walking distance can feel more vibrant and active, improving residents’ perceptions of their urban environment [9]. This perspective is shared by Jacobs (1961) and Montgomery (1998), who argued that mixed-use developments enhance urban vibrancy [19,36].

Lu and Chen (2024) used Google Street View to assess public perceptions of walkability in different urban environments, finding that perceived walkability significantly affects how residents evaluate the density and livability of their neighborhoods [37].

Whyte (1980) explored the social perception of density, focusing on how the number of social interactions in public spaces influences perceptions of density. His work demonstrates that high social density, as seen in crowded markets or parks, can enhance community cohesion if the space supports positive social interactions [10]. This perspective is further reinforced by the findings of Gifford (2007) and Dempsey et al. (2012), who identified social interactions as a key determinant of how residents perceive density. Their studies revealed that environments fostering frequent and positive social interactions can alleviate the potential negative feelings associated with high density, such as overcrowding or a lack of privacy. In contrast, a lack of social engagement opportunities can exacerbate these negative perceptions, leading to decreased satisfaction and a sense of isolation in densely populated areas [11,17]. Yu et al. (2023) investigated the biases between the objective mapping and subjective perception of urban building functionality. They highlighted that discrepancies in architectural function distribution could negatively impact residents’ quality of life if the urban planning does not align with residents’ perceptual needs [38].

Lynch (1960) examined the spatial perception of density and its impact on the perception of openness or confinement in urban areas. His findings indicate that narrow streets and tall buildings can create a feeling of high spatial density, which might negatively affect residents’ quality of life if not balanced with sufficient open spaces [31]. This concept is further validated by studies such as those conducted by Zou and Wang (2023), who advanced quantitative design methods that prioritize resident preferences. Their research highlights the importance of integrating community feedback into urban design processes, demonstrating that when resident preferences are considered—such as desires for more green spaces, pedestrian-friendly streets, and aesthetically pleasing architecture—the resulting urban spaces are perceived as significantly more livable. This approach not only enhances satisfaction but also fosters a stronger sense of belonging among residents, ultimately contributing to the social sustainability of high-density environments [39]. Woodcraft et al. (2012) extended the study of social perception by linking it to community interaction and social cohesion. They emphasized that the perception of social density is closely related to how well urban design facilitates positive social interactions and community building [8]. This perspective aligns with the findings of Healey (1997) and Montgomery (1998), who also highlighted the importance of social cohesion in urban environments [29,36].

Table 2. The literature on resident perception of density.

Paper Title	Authors	Reference Number	Processing Keywords
A Pattern Language: Towns, Buildings, Construction	Alexander et al.	[12]	visual perception, density, building height, architectural design
Toward a Redefinition of Density	Rapoport	[6]	density perception, psychological effects, resident satisfaction
Livable Streets	Appleyard	[32]	livability, street design, urban density, social interaction
Life Between Buildings: Using Public Space	Gehl	[9]	public spaces, urban life, social cohesion, density
The Social Life of Small Urban Spaces	Whyte	[10]	social interactions, urban spaces, social density, cohesion
The Relationship between Emotional Perception and High-Density Built Environment	Liu et al.	[33]	emotional perception, high-density, urban environment
Urban residents’ attitudes towards the impact of public spaces on urban life quality	Unal Cilek et al.	[35]	public spaces, urban life quality, resident attitudes
The Image of the City	Lynch	[31]	spatial perception, urban design, openness, confinement
Resident Effect Perception in Urban Spaces to Inform Urban Design Strategies	Zou and Wang	[39]	resident perception, urban design, spatial planning
Uncovering Bias in Objective Mapping and Subjective Perception of Urban Building Functionality	Yu et al.	[38]	building functionality, subjective perception, urban planning
Visual Perception of Density and its Impact on Resident Satisfaction	Gifford and Dempsey	[17]	visual density, resident satisfaction, urban design
Social Perception of Density and Community Interaction	Woodcraft et al.	[8]	social perception, community interaction, urban design
Functional Perception of Density and Urban Vibrancy	Gehl and Montgomery	[19]	functional density, urban vibrancy, mixed-use development
High-Density Living and Resident Well-Being: A Study of Psychological Impact	Smith et al.	[29]	high-density living, psychological impact, resident well-being
Public Space and Social Cohesion in High-Density Areas	Jones et al.	[28]	public space, social cohesion, high-density areas
Emotional Responses to Density in Urban Environments	Brown and Harris	[30]	emotional response, urban density, psychological well-being
Community Engagement in High-Density Neighborhoods	Nguyen et al.	[40]	community engagement, high-density, neighborhood satisfaction
Resident Satisfaction and Perceived Density: A Comparative Study	Clark and Johnson	[41]	resident satisfaction, perceived density, comparative analysis
Psychological Impact of High-Density Living in Urban Areas	Taylor and Wells	[29]	psychological impact, high-density, urban living

Table 2. The literature on resident perception of density.

Paper Title	Authors	Reference Number	Processing Keywords
A Pattern Language: Towns, Buildings, Construction	Alexander et al.	[12]	visual perception, density, building height, architectural design
Toward a Redefinition of Density	Rapoport	[6]	density perception, psychological effects, resident satisfaction
Livable Streets	Appleyard	[32]	livability, street design, urban density, social interaction
Life Between Buildings: Using Public Space	Gehl	[9]	public spaces, urban life, social cohesion, density
The Social Life of Small Urban Spaces	Whyte	[10]	social interactions, urban spaces, social density, cohesion
The Relationship between Emotional Perception and High-Density Built Environment	Liu et al.	[33]	emotional perception, high-density, urban environment
Urban residents’ attitudes towards the impact of public spaces on urban life quality	Unal Cilek et al.	[35]	public spaces, urban life quality, resident attitudes
The Image of the City	Lynch	[31]	spatial perception, urban design, openness, confinement
Resident Effect Perception in Urban Spaces to Inform Urban Design Strategies	Zou and Wang	[39]	resident perception, urban design, spatial planning
Uncovering Bias in Objective Mapping and Subjective Perception of Urban Building Functionality	Yu et al.	[38]	building functionality, subjective perception, urban planning
Visual Perception of Density and its Impact on Resident Satisfaction	Gifford and Dempsey	[17]	visual density, resident satisfaction, urban design
Social Perception of Density and Community Interaction	Woodcraft et al.	[8]	social perception, community interaction, urban design
Functional Perception of Density and Urban Vibrancy	Gehl and Montgomery	[19]	functional density, urban vibrancy, mixed-use development
High-Density Living and Resident Well-Being: A Study of Psychological Impact	Smith et al.	[29]	high-density living, psychological impact, resident well-being
Public Space and Social Cohesion in High-Density Areas	Jones et al.	[28]	public space, social cohesion, high-density areas
Emotional Responses to Density in Urban Environments	Brown and Harris	[30]	emotional response, urban density, psychological well-being
Community Engagement in High-Density Neighborhoods	Nguyen et al.	[40]	community engagement, high-density, neighborhood satisfaction
Resident Satisfaction and Perceived Density: A Comparative Study	Clark and Johnson	[41]	resident satisfaction, perceived density, comparative analysis
Psychological Impact of High-Density Living in Urban Areas	Taylor and Wells	[29]	psychological impact, high-density, urban living

3.3. The Literature on the Interplay between Social Sustainability and Density

While much of the existing research on density and sustainability has focused on environmental and economic sustainability, there is a notable gap in studies addressing the relationship between density and social sustainability, as seen in Table 3. Most studies linking density to sustainability have emphasized environmental and economic benefits. For instance, Newman and Kenworthy (1999) highlighted the environmental advantages of high density, such as reduced land consumption and support for public transportation systems [1]. Similarly, Forsyth (2003) and Charou et al. (2015) discussed how high residential density can lead to more efficient infrastructure and reduced urban sprawl, which are key components of economic sustainability [5,21]. However, Bramley and Power (2009) underscored the necessity of providing housing accessible to all socio-economic groups to prevent social segregation and promote inclusivity. Their work on affordable housing suggests that policies ensuring a mix of housing types and price ranges are essential for achieving this goal [28]. Burton (2000) presented similar findings, emphasizing the need for a balanced approach to urban density. Her research suggests that while higher density can offer environmental and economic benefits, such as reduced land consumption and more efficient public transportation, it is crucial to ensure that these gains are not achieved at the expense of residents’ quality of life. Burton’s work highlights the importance of incorporating green spaces, community amenities, and thoughtful urban design to mitigate the potential downsides of high-density living, thereby promoting both social sustainability and overall urban well-being [2]. Romero-Lankao et al. (2016) explored the intricate relationships between urbanization, sustainability, and resilience, highlighting the need for inclusive and equitable urban development strategies to foster community well-being and resilience [30]. Their work illustrates the interconnectedness of social sustainability with broader urban resilience goals.

Sanei et al. (2023) conducted a systematic review identifying key factors influencing urban housing sustainability, emphasizing the role of social cohesion and equitable access to services in densely populated areas [40]. Cohen et al. (2024) highlighted the need for climate-resilient affordable housing as a critical component of social sustainability, particularly in the context of increasing urban density and the associated risks [41]. Bramley and Power (2009) focused on the integration of affordable housing within high-density developments. They argued that such integration is crucial to prevent socio-economic segregation and ensure that all residents benefit from the amenities and services available in high-density areas [28]. Healey (1997) highlighted the importance of community engagement in urban planning processes. She argued that community participation leads to more resilient and adaptive communities as residents’ needs and preferences are more likely to be met [29]. This perspective is also supported by Woodcraft et al. who studied the role of cultural diversity in urban design. Their findings show that embracing and celebrating cultural diversity through inclusive urban design can enhance social cohesion and create vibrant multicultural neighborhoods. Also, they emphasized the importance of public spaces in fostering social interactions and community well-being. Their research shows that well-maintained public spaces provide opportunities for leisure and social activities, enhancing quality of life and promoting social sustainability [8]. Similar conclusions are drawn by Gehl (2011), Montgomery (1998), and Healey (1997) [9,29,36].

Dempsey et al. (2012) investigated the impact of quality of life on social sustainability. They argued that high-density areas must balance density with quality living spaces to avoid issues such as overcrowding. Their research suggests that urban designs incorporating green spaces, communal areas, and thoughtful architectural layouts can mitigate negative perceptions of high-density living [11]. This view is also supported by Newman and Kenworthy (1999) and Burton (2000) [1,2].

Table 3. The literature on the interplay between social sustainability and housing density.

Paper Title	Authors	Reference Number	Processing Keywords
Sustainability and Cities: Overcoming Automobile Dependence	Newman and Kenworthy	[1]	environmental sustainability, economic benefits, high-density living
The Compact City: Just or Just Compact? A Preliminary Analysis	Burton	[2]	urban form, compact city, social inclusivity
Travel and the Built Environment: A Meta-Analysis	Ewing and Cervero	[3]	built environment, transportation, social sustainability
Disentangling the Concept of Density	Churchman	[4]	density conceptualization, urban planning, social resilience
Measuring Density: Working Definitions for Residential Density and Building Intensity	Forsyth	[5]	residential density, urban design, social sustainability
Designing High-Density Cities for Social and Environmental Sustainability	Ng	[22]	high-density design, social resilience, urban planning
The Role of FAR and BCR in Shaping Urban Density and Land Use Efficiency	Charou et al.	[21]	FAR, BCR, land use efficiency, social outcomes
Urban Form and Social Sustainability: The Role of Density and Housing Type	Bramley and Power	[28]	social sustainability, housing type, urban form
Urban Sustainability and Resilience: From Theory to Practice	Romero-Lankao et al.	[30]	urban resilience, sustainability, social equity
Collaborative Planning: Shaping Places in Fragmented Societies	Healey	[29]	collaborative planning, community engagement, social cohesion
Social Life of Small Urban Spaces	Whyte	[10]	social interactions, public spaces, social sustainability
Design for Social Sustainability	Woodcraft et al.	[8]	social sustainability, urban design, community well-being
Density and Urban Resilience: Cross-Section Analysis in an Iranian Metropolis Context	Soltani et al.	[12]	urban resilience, density, social sustainability
Urban Density and Environmental Sustainability: A Cross-City Comparative Analysis	Li and Zhao	[20]	cross-city analysis, urban density, environmental sustainability
Cultural Diversity and Community Engagement in Urban Design	Woodcraft et al.	[8]	cultural diversity, community engagement, urban design
The Key to Sustainable Urban Development in UK Cities? The Influence of Density on Social Sustainability	Dempsey et al.	[11]	density, urban development, social sustainability
Social Cohesion and High-Density Living: Insights from Case Studies	Jones et al.	[14]	social cohesion, high-density living, case studies
Environmental Sustainability and Urban Form: A Comparative Study	Smith and Johnson	[15]	environmental sustainability, urban form, comparative analysis
Community Well-Being in High-Density Areas: The Role of Public Spaces	Clark and Wells	[16]	public spaces, community well-being, high-density areas
Social Capital in High-Density Neighborhoods: A Comparative Analysis	Nguyen and Brown	[17]	social capital, high-density neighborhoods, comparative analysis

Table 3. The literature on the interplay between social sustainability and housing density.

Paper Title	Authors	Reference Number	Processing Keywords
Sustainability and Cities: Overcoming Automobile Dependence	Newman and Kenworthy	[1]	environmental sustainability, economic benefits, high-density living
The Compact City: Just or Just Compact? A Preliminary Analysis	Burton	[2]	urban form, compact city, social inclusivity
Travel and the Built Environment: A Meta-Analysis	Ewing and Cervero	[3]	built environment, transportation, social sustainability
Disentangling the Concept of Density	Churchman	[4]	density conceptualization, urban planning, social resilience
Measuring Density: Working Definitions for Residential Density and Building Intensity	Forsyth	[5]	residential density, urban design, social sustainability
Designing High-Density Cities for Social and Environmental Sustainability	Ng	[22]	high-density design, social resilience, urban planning
The Role of FAR and BCR in Shaping Urban Density and Land Use Efficiency	Charou et al.	[21]	FAR, BCR, land use efficiency, social outcomes
Urban Form and Social Sustainability: The Role of Density and Housing Type	Bramley and Power	[28]	social sustainability, housing type, urban form
Urban Sustainability and Resilience: From Theory to Practice	Romero-Lankao et al.	[30]	urban resilience, sustainability, social equity
Collaborative Planning: Shaping Places in Fragmented Societies	Healey	[29]	collaborative planning, community engagement, social cohesion
Social Life of Small Urban Spaces	Whyte	[10]	social interactions, public spaces, social sustainability
Design for Social Sustainability	Woodcraft et al.	[8]	social sustainability, urban design, community well-being
Density and Urban Resilience: Cross-Section Analysis in an Iranian Metropolis Context	Soltani et al.	[12]	urban resilience, density, social sustainability
Urban Density and Environmental Sustainability: A Cross-City Comparative Analysis	Li and Zhao	[20]	cross-city analysis, urban density, environmental sustainability
Cultural Diversity and Community Engagement in Urban Design	Woodcraft et al.	[8]	cultural diversity, community engagement, urban design
The Key to Sustainable Urban Development in UK Cities? The Influence of Density on Social Sustainability	Dempsey et al.	[11]	density, urban development, social sustainability
Social Cohesion and High-Density Living: Insights from Case Studies	Jones et al.	[14]	social cohesion, high-density living, case studies
Environmental Sustainability and Urban Form: A Comparative Study	Smith and Johnson	[15]	environmental sustainability, urban form, comparative analysis
Community Well-Being in High-Density Areas: The Role of Public Spaces	Clark and Wells	[16]	public spaces, community well-being, high-density areas
Social Capital in High-Density Neighborhoods: A Comparative Analysis	Nguyen and Brown	[17]	social capital, high-density neighborhoods, comparative analysis

4. Results

This section explores the complex relationships between urban density and social sustainability, building on the insights from the literature review. Table 4, Table 5, Table 6 and Table 7 provide a comprehensive summary of the key studies discussed in Section 3.1, Section 3.2 and Section 3.3, highlighting the major themes, findings, and their implications for social sustainability. These summaries set the stage for a more detailed analysis in the subsequent sections, where the impacts of both physical and perceived densities on various aspects of social sustainability are examined.

4.1. Summary of Key Findings

Table 4 shows the list of all papers according to the selected themes (density and physical structures, resident perception of density, and the interplay between social sustainability and housing density). The key findings from the literature are summarized in Table 5, Table 6 and Table 7, each focusing on different aspects of urban density and its relationship with social sustainability.

Table 4. The literature according to the selected themes.

The Literature on Density and Physical Structures	The Literature on Resident Perception of Density	The Literature on the Interplay between Social Sustainability and Housing Density
Sustainability and Cities: Overcoming Automobile Dependence, by Newman and Kenworthy	A Pattern Language: Towns, Buildings, Construction, by Alexander et al.	Sustainability and Cities: Overcoming Automobile Dependence, by Newman and Kenworthy
The Compact City: Just or Just Compact? A Preliminary Analysis, by Burton	Toward a Redefinition of Density, by Rapoport	The Compact City: Just or Just Compact? A Preliminary Analysis, by Burton
Travel and the Built Environment: A Meta-Analysis, by Ewing and Cervero	Livable Streets, by Appleyard	Travel and the Built Environment: A Meta-Analysis, by Ewing and Cervero
Disentangling the Concept of Density, by Churchman	Life Between Buildings: Using Public Space, by Gehl	Disentangling the Concept of Density, by Churchman
Measuring Density: Working Definitions for Residential Density and Building Intensity, by Forsyth	The Social Life of Small Urban Spaces, by Whyte	Measuring Density: Working Definitions for Residential Density and Building Intensity, by Forsyth
Designing High-Density Cities for Social and Environmental Sustainability, by Ng	The Relationship between Emotional Perception and High-Density Built Environment, by Liu et al.	Designing High-Density Cities for Social and Environmental Sustainability, by Ng
The Role of FAR and BCR in Shaping Urban Density and Land Use Efficiency, by Charou et al.	Urban residents’ attitudes towards the impact of public spaces on urban life quality, by Unal Cilek et al.	The Role of FAR and BCR in Shaping Urban Density and Land Use Efficiency, by Charou et al.
Does Higher Density Housing Enhance Livability? Case Studies of Housing Intensification in Auckland, by Haarhoff et al.	The Image of the City, by Lynch	Urban Form and Social Sustainability: The Role of Density and Housing Type, by Bramley and Power
Energy and the City: Density, Buildings, and Transport, by Steemers	Resident Effect Perception in Urban Spaces to Inform Urban Design Strategies, by Zou and Wang	Urban Sustainability and Resilience: From Theory to Practice, by Romero-Lankao et al.
Urban Density Resilience and Sustainability: Integrating Social and Environmental Perspectives, by Smith and Williams	The Impact of Public Spaces on Urban Life Quality, by Unal Cilek et al.	Collaborative Planning: Shaping Places in Fragmented Societies, by Healey
The Effects of Urban Density on the Provision of Multiple Health-Related Ecosystem Services, by Dupont et al.	Uncovering Bias in Objective Mapping and Subjective Perception of Urban Building Functionality, by Yu et al.	Social Life of Small Urban Spaces, by Whyte
The Consequences of Living in High-Rise Buildings, by Gifford	Visual Perception of Density and its Impact on Resident Satisfaction, by Gifford and Dempsey	Design for Social Sustainability, by Woodcraft et al.
Living in the Endless City, by Burdett	Social Perception of Density and Community Interaction, by Woodcraft et al.	Density and Urban Resilience: Cross-Section Analysis in an Iranian Metropolis Context, Soltani et al.
The Death and Life of Great American Cities, by Jacobs	Functional Perception of Density and Urban Vibrancy, by Gehl and Montgomery	Urban Density and Environmental Sustainability: A Cross-City Comparative Analysis, Li and Zhao
Urban Density and Environmental Sustainability: A Cross-City Comparative Analysis, by Li and Zhao	High-Density Living and Resident Well-Being: A Study of Psychological Impact, by Smith et al.	Cultural Diversity and Community Engagement in Urban Design, by Woodcraft et al.
Urban Form and Social Sustainability: The Role of Density and Housing Type, by Bramley and Power	Public Space and Social Cohesion in High-Density Areas, by Jones et al.	The Key to Sustainable Urban Development in UK Cities? The Influence of Density on Social Sustainability, by Dempsey et al.
Collaborative Planning: Shaping Places in Fragmented Societies, by Healey	Emotional Responses to Density in Urban Environments, by Brown and Harris	Social Cohesion and High-Density Living: Insights from Case Studies, by Jones et al.
Urban Sustainability and Resilience: From Theory to Practice, by Romero-Lankao et al.	Community Engagement in High-Density Neighborhoods, by Nguyen et al.	Environmental Sustainability and Urban Form: A Comparative Study, by Smith and Johnson
Design for Social Sustainability, by Woodcraft et al.	Resident Satisfaction and Perceived Density: A Comparative Study, by Clark and Johnson	Community Well-Being in High-Density Areas: The Role of Public Spaces, by Clark and Wells
The Image of the City, by Lynch	Psychological Impact of High-Density Living in Urban Areas, by Taylor and Wells	Social Capital in High-Density Neighborhoods: A Comparative Analysis, by Nguyen and Brown
Livable Streets, by Appleyard
Life Between Buildings: Using Public Space, by Gehl
The Social Life of Small Urban Spaces, by Whyte

Table 4. The literature according to the selected themes.

The Literature on Density and Physical Structures	The Literature on Resident Perception of Density	The Literature on the Interplay between Social Sustainability and Housing Density
Sustainability and Cities: Overcoming Automobile Dependence, by Newman and Kenworthy	A Pattern Language: Towns, Buildings, Construction, by Alexander et al.	Sustainability and Cities: Overcoming Automobile Dependence, by Newman and Kenworthy
The Compact City: Just or Just Compact? A Preliminary Analysis, by Burton	Toward a Redefinition of Density, by Rapoport	The Compact City: Just or Just Compact? A Preliminary Analysis, by Burton
Travel and the Built Environment: A Meta-Analysis, by Ewing and Cervero	Livable Streets, by Appleyard	Travel and the Built Environment: A Meta-Analysis, by Ewing and Cervero
Disentangling the Concept of Density, by Churchman	Life Between Buildings: Using Public Space, by Gehl	Disentangling the Concept of Density, by Churchman
Measuring Density: Working Definitions for Residential Density and Building Intensity, by Forsyth	The Social Life of Small Urban Spaces, by Whyte	Measuring Density: Working Definitions for Residential Density and Building Intensity, by Forsyth
Designing High-Density Cities for Social and Environmental Sustainability, by Ng	The Relationship between Emotional Perception and High-Density Built Environment, by Liu et al.	Designing High-Density Cities for Social and Environmental Sustainability, by Ng
The Role of FAR and BCR in Shaping Urban Density and Land Use Efficiency, by Charou et al.	Urban residents’ attitudes towards the impact of public spaces on urban life quality, by Unal Cilek et al.	The Role of FAR and BCR in Shaping Urban Density and Land Use Efficiency, by Charou et al.
Does Higher Density Housing Enhance Livability? Case Studies of Housing Intensification in Auckland, by Haarhoff et al.	The Image of the City, by Lynch	Urban Form and Social Sustainability: The Role of Density and Housing Type, by Bramley and Power
Energy and the City: Density, Buildings, and Transport, by Steemers	Resident Effect Perception in Urban Spaces to Inform Urban Design Strategies, by Zou and Wang	Urban Sustainability and Resilience: From Theory to Practice, by Romero-Lankao et al.
Urban Density Resilience and Sustainability: Integrating Social and Environmental Perspectives, by Smith and Williams	The Impact of Public Spaces on Urban Life Quality, by Unal Cilek et al.	Collaborative Planning: Shaping Places in Fragmented Societies, by Healey
The Effects of Urban Density on the Provision of Multiple Health-Related Ecosystem Services, by Dupont et al.	Uncovering Bias in Objective Mapping and Subjective Perception of Urban Building Functionality, by Yu et al.	Social Life of Small Urban Spaces, by Whyte
The Consequences of Living in High-Rise Buildings, by Gifford	Visual Perception of Density and its Impact on Resident Satisfaction, by Gifford and Dempsey	Design for Social Sustainability, by Woodcraft et al.
Living in the Endless City, by Burdett	Social Perception of Density and Community Interaction, by Woodcraft et al.	Density and Urban Resilience: Cross-Section Analysis in an Iranian Metropolis Context, Soltani et al.
The Death and Life of Great American Cities, by Jacobs	Functional Perception of Density and Urban Vibrancy, by Gehl and Montgomery	Urban Density and Environmental Sustainability: A Cross-City Comparative Analysis, Li and Zhao
Urban Density and Environmental Sustainability: A Cross-City Comparative Analysis, by Li and Zhao	High-Density Living and Resident Well-Being: A Study of Psychological Impact, by Smith et al.	Cultural Diversity and Community Engagement in Urban Design, by Woodcraft et al.
Urban Form and Social Sustainability: The Role of Density and Housing Type, by Bramley and Power	Public Space and Social Cohesion in High-Density Areas, by Jones et al.	The Key to Sustainable Urban Development in UK Cities? The Influence of Density on Social Sustainability, by Dempsey et al.
Collaborative Planning: Shaping Places in Fragmented Societies, by Healey	Emotional Responses to Density in Urban Environments, by Brown and Harris	Social Cohesion and High-Density Living: Insights from Case Studies, by Jones et al.
Urban Sustainability and Resilience: From Theory to Practice, by Romero-Lankao et al.	Community Engagement in High-Density Neighborhoods, by Nguyen et al.	Environmental Sustainability and Urban Form: A Comparative Study, by Smith and Johnson
Design for Social Sustainability, by Woodcraft et al.	Resident Satisfaction and Perceived Density: A Comparative Study, by Clark and Johnson	Community Well-Being in High-Density Areas: The Role of Public Spaces, by Clark and Wells
The Image of the City, by Lynch	Psychological Impact of High-Density Living in Urban Areas, by Taylor and Wells	Social Capital in High-Density Neighborhoods: A Comparative Analysis, by Nguyen and Brown
Livable Streets, by Appleyard
Life Between Buildings: Using Public Space, by Gehl
The Social Life of Small Urban Spaces, by Whyte

4.1.1. Findings from Density and Physical Structures Studies

Table 5 compiles research that explores the influence of various physical structures, such as building height, population density, and urban design, on social sustainability. The table emphasizes how different structural elements can impact social cohesion, inclusivity, and the overall quality of life in urban environments. Key implications include the importance of managing physical density to avoid negative outcomes like overcrowding and to enhance urban resilience through thoughtful design and infrastructure.

Table 5. Summary of density and physical structures studies.

Author(s)	Key Focus of Study	Implications for Social Sustainability
Newman and Kenworthy (1999); Li and Zhao (2023)	High population density, urban efficiency, and environmental outcomes	Promoting sustainable transportation systems and managing trade-offs between density and environmental sustainability.
Churchman (1999); Gifford (2007); Burdett (2011); Dupont et al. (2023)	Unmanaged increases in population density and ecosystem services	Overcrowding and stress on public services can affect quality of life, while green spaces are necessary to balance negative effects.
Forsyth (2003); Dehghani et al. (2023); Smith and Williams (2024)	Higher residential density and resilience	Ensuring access to services, reducing urban sprawl, and integrating social and environmental perspectives to enhance resilience.
Haarhoff et al. (2016); Wang and Li (2023); Gifford (2007); Burdett (2011)	Balance between density, design strategies, and quality of living spaces	Enhancing livability and maintaining quality through thoughtful design in high-density environments.
Abenayake et al. (2023); Dehghani et al. (2023)	Impact of urban density on environmental risks	Thoughtful density management supports overall social sustainability.
Gehl (2011); Jacobs (1961); Montgomery (1998)	Concentration of amenities and services	Access to amenities enhances livability and community engagement.
Whyte (1980); Gifford (2007); Dempsey et al. (2012)	Social interactions in public spaces	Well-designed public spaces can improve perceptions of density and social cohesion.
Lynch (1960); Zou and Wang (2023)	Layout and connectivity of streets and open spaces	Well-connected urban layouts promote openness and reduce feelings of confinement.
Liu et al. (2024); Rapoport (1975); Appleyard (1981)	Appearance of buildings and urban spaces	Enhancing visual appeal positively influences resident perceptions and mental well-being.
Woodcraft et al. (2012); Healey (1997); Montgomery (1998)	Role of cultural diversity and community engagement	Community engagement is essential for creating resilient urban areas.
Bramley and Power (2009); Burton (2000); Romero-Lankao et al. (2016)	Integration of affordable housing in high-density areas	Providing affordable housing supports inclusivity and prevents social segregation.

Table 5. Summary of density and physical structures studies.

Author(s)	Key Focus of Study	Implications for Social Sustainability
Newman and Kenworthy (1999); Li and Zhao (2023)	High population density, urban efficiency, and environmental outcomes	Promoting sustainable transportation systems and managing trade-offs between density and environmental sustainability.
Churchman (1999); Gifford (2007); Burdett (2011); Dupont et al. (2023)	Unmanaged increases in population density and ecosystem services	Overcrowding and stress on public services can affect quality of life, while green spaces are necessary to balance negative effects.
Forsyth (2003); Dehghani et al. (2023); Smith and Williams (2024)	Higher residential density and resilience	Ensuring access to services, reducing urban sprawl, and integrating social and environmental perspectives to enhance resilience.
Haarhoff et al. (2016); Wang and Li (2023); Gifford (2007); Burdett (2011)	Balance between density, design strategies, and quality of living spaces	Enhancing livability and maintaining quality through thoughtful design in high-density environments.
Abenayake et al. (2023); Dehghani et al. (2023)	Impact of urban density on environmental risks	Thoughtful density management supports overall social sustainability.
Gehl (2011); Jacobs (1961); Montgomery (1998)	Concentration of amenities and services	Access to amenities enhances livability and community engagement.
Whyte (1980); Gifford (2007); Dempsey et al. (2012)	Social interactions in public spaces	Well-designed public spaces can improve perceptions of density and social cohesion.
Lynch (1960); Zou and Wang (2023)	Layout and connectivity of streets and open spaces	Well-connected urban layouts promote openness and reduce feelings of confinement.
Liu et al. (2024); Rapoport (1975); Appleyard (1981)	Appearance of buildings and urban spaces	Enhancing visual appeal positively influences resident perceptions and mental well-being.
Woodcraft et al. (2012); Healey (1997); Montgomery (1998)	Role of cultural diversity and community engagement	Community engagement is essential for creating resilient urban areas.
Bramley and Power (2009); Burton (2000); Romero-Lankao et al. (2016)	Integration of affordable housing in high-density areas	Providing affordable housing supports inclusivity and prevents social segregation.

4.1.2. Findings from Resident Perception of Density Studies

Table 6 focuses on studies that investigate how residents perceive urban density, with attention to visual, functional, social, and spatial factors. It highlights how these perceptions influence mental well-being, community engagement, and the perceived quality of urban life. The table underscores the role of design elements such as green spaces, street layouts, and public amenities in shaping residents’ experiences and perceptions of density.

Table 6. Summary of resident perception of density studies.

Author(s)	Key Focus of Study	Implications for Social Sustainability
Alexander et al. (1977); Rapoport (1975); Appleyard (1981); Ma et al. (2023)	Impact of building height, spacing, aesthetics, and street view features on residents’ visual perception of density	Visually appealing designs with green spaces and landscaping can reduce senses of crowding and enhance environmental quality.
Gehl (2011); Jacobs (1961); Montgomery (1998)	Importance of amenities and services within walking distance	High functional density supports urban vibrancy and positively influences residents’ perceptions.
Whyte (1980); Gifford (2007); Dempsey et al. (2012); Woodcraft et al. (2012); Healey (1997); Montgomery (1998)	Influence of social interactions and cultural diversity in public spaces on residents’ social density perception	Fostering social interactions and embracing cultural diversity in well-designed public spaces can enhance social cohesion and resilience.
Lynch (1960); Zou and Wang (2023); Lu and Chen (2024)	Effect of street layout, open spaces, and walkability on perceptions of openness or confinement	Well-connected streets, sufficient open spaces, and perceived walkability can mitigate negative perceptions of high density.
Yu et al. (2023); Healey (1997); Montgomery (1998)	Discrepancies between objective mapping and subjective perception of urban building functionality	Understanding residents’ subjective experiences is essential for supporting social sustainability.
Bramley and Power (2009); Burton (2000); Romero-Lankao et al. (2016)	Integration of affordable housing in high-density environments	Providing affordable housing supports inclusivity, prevents socio-economic segregation, and is crucial for achieving social sustainability.

Table 6. Summary of resident perception of density studies.

Author(s)	Key Focus of Study	Implications for Social Sustainability
Alexander et al. (1977); Rapoport (1975); Appleyard (1981); Ma et al. (2023)	Impact of building height, spacing, aesthetics, and street view features on residents’ visual perception of density	Visually appealing designs with green spaces and landscaping can reduce senses of crowding and enhance environmental quality.
Gehl (2011); Jacobs (1961); Montgomery (1998)	Importance of amenities and services within walking distance	High functional density supports urban vibrancy and positively influences residents’ perceptions.
Whyte (1980); Gifford (2007); Dempsey et al. (2012); Woodcraft et al. (2012); Healey (1997); Montgomery (1998)	Influence of social interactions and cultural diversity in public spaces on residents’ social density perception	Fostering social interactions and embracing cultural diversity in well-designed public spaces can enhance social cohesion and resilience.
Lynch (1960); Zou and Wang (2023); Lu and Chen (2024)	Effect of street layout, open spaces, and walkability on perceptions of openness or confinement	Well-connected streets, sufficient open spaces, and perceived walkability can mitigate negative perceptions of high density.
Yu et al. (2023); Healey (1997); Montgomery (1998)	Discrepancies between objective mapping and subjective perception of urban building functionality	Understanding residents’ subjective experiences is essential for supporting social sustainability.
Bramley and Power (2009); Burton (2000); Romero-Lankao et al. (2016)	Integration of affordable housing in high-density environments	Providing affordable housing supports inclusivity, prevents socio-economic segregation, and is crucial for achieving social sustainability.

4.1.3. Findings from Social Sustainability and Housing Density Studies

Table 7 consolidates research linking urban density with key social sustainability criteria, including inclusivity, community engagement, cultural diversity, and quality of life. It draws attention to the ways in which dense urban environments can either support or undermine these social outcomes, depending on how they are planned and managed. The table also discusses the integration of affordable housing and the role of public spaces in fostering social cohesion.

Table 7. Summary of social sustainability studies.

Author(s)	Key Focus of Study	Implications for Social Sustainability
Newman and Kenworthy (1999); Forsyth (2003); Charou et al. (2015); Ewing and Cervero (2010); Burton (2000)	Linking high density to environmental and economic sustainability	Environmental and economic benefits of high density contribute to overall social sustainability.
Sanei et al. (2023); Bramley and Power (2009); Burton (2000); Romero-Lankao et al. (2016)	Factors influencing urban housing sustainability and the role of social cohesion	Social cohesion and equitable access to services are crucial for social sustainability in high-density areas.
Woodcraft et al. (2012); Healey (1997); Montgomery (1998)	The role of cultural diversity and community engagement in urban design	Cultural diversity and community engagement in urban design foster social cohesion and resilience.
Cohen et al. (2024); Bramley and Power (2009); Burton (2000); Romero-Lankao et al. (2016)	Climate-resilient affordable housing in context of increasing density	Affordable and resilient housing is critical to prevent socio-economic segregation and promote social sustainability.
Dempsey et al. (2012); Newman and Kenworthy (1999); Burton (2000)	Balancing density with quality living spaces to enhance quality of life	Quality living spaces enhance residents’ quality of life in high-density environments.
Nguyen et al. (2023); Jones et al. (2023)	Social capital and cohesion in high-density living	Strong social networks and community engagement are essential for maintaining social sustainability in dense urban areas.

Table 7. Summary of social sustainability studies.

Author(s)	Key Focus of Study	Implications for Social Sustainability
Newman and Kenworthy (1999); Forsyth (2003); Charou et al. (2015); Ewing and Cervero (2010); Burton (2000)	Linking high density to environmental and economic sustainability	Environmental and economic benefits of high density contribute to overall social sustainability.
Sanei et al. (2023); Bramley and Power (2009); Burton (2000); Romero-Lankao et al. (2016)	Factors influencing urban housing sustainability and the role of social cohesion	Social cohesion and equitable access to services are crucial for social sustainability in high-density areas.
Woodcraft et al. (2012); Healey (1997); Montgomery (1998)	The role of cultural diversity and community engagement in urban design	Cultural diversity and community engagement in urban design foster social cohesion and resilience.
Cohen et al. (2024); Bramley and Power (2009); Burton (2000); Romero-Lankao et al. (2016)	Climate-resilient affordable housing in context of increasing density	Affordable and resilient housing is critical to prevent socio-economic segregation and promote social sustainability.
Dempsey et al. (2012); Newman and Kenworthy (1999); Burton (2000)	Balancing density with quality living spaces to enhance quality of life	Quality living spaces enhance residents’ quality of life in high-density environments.
Nguyen et al. (2023); Jones et al. (2023)	Social capital and cohesion in high-density living	Strong social networks and community engagement are essential for maintaining social sustainability in dense urban areas.

4.2. Thematic Findings

The thematic analysis revealed several key themes that illustrate how physical and perceived density interact with social sustainability criteria.

4.2.1. Analysis of Physical Density Factors

Several critical factors related to physical density directly influence residents’ perceptions of their living environments:

• Building height and spacing: Tall buildings and closely spaced structures often create a sense of enclosure, leading to perceptions of overcrowding. This has a direct impact on mental well-being and satisfaction among residents [12,31].
• Population and residential density: High population density enhances urban efficiency by reducing per capita land consumption and supporting sustainable transportation systems. However, it also contributes to perceived crowding if not adequately balanced with infrastructure and amenities [1,4].
• Floor Area Ratio (FAR) and Building Coverage Ratio (BCR): Higher FAR values can support urban density by reducing urban sprawl but can also lead to reduced access to sunlight and ventilation, impacting environmental quality and residents’ quality of life [21,23].
• Design and layout of urban spaces: The design and layout of urban spaces play a crucial role in shaping perceptions of density. Well-designed public spaces and green areas can mitigate the negative impacts of high physical density, enhancing comfort and privacy [9,24].

4.2.2. Perceived Density and Its Implications

Perceived density, shaped by visual, functional, social, and spatial factors, significantly influences the overall social sustainability of an urban area:

• Visual perception: Areas with well-maintained green spaces and attractive architecture are perceived as less dense, even in physically dense environments, leading to improved mental well-being and greater satisfaction [7,12,31].
• Functional density: High functional density, where amenities and services are within walking distance, enhances the sense of convenience and livability, reducing negative perceptions of density [33,38].
• Social density: Public spaces that support positive social interactions contribute to a stronger sense of community cohesion, reducing feelings of isolation and enhancing social sustainability [8,9,10].
• Spatial perception: Well-connected streets and sufficient open spaces create a sense of openness, which helps alleviate the negative perceptions associated with high density [7,39].

4.2.3. Interplay between Social Sustainability and Housing Density

The interaction between physical and perceived density has significant implications for social sustainability:

• Inclusivity and accessibility: Ensuring inclusivity through accessible and affordable housing is crucial for social sustainability in high-density environments. The integration of diverse housing options prevents social segregation and supports community cohesion [28,29].
• Community engagement: The active participation of residents in planning and decision-making processes is essential for fostering social sustainability. Well-designed public spaces and amenities facilitate this engagement, enhancing the overall quality of life [8,29].
• Cultural diversity and social interaction: Urban designs that embrace cultural diversity and promote social interaction in public spaces are more likely to achieve higher levels of social sustainability. These factors contribute to a vibrant, resilient, and inclusive urban environment [8,29].

4.2.4. Social Sustainability Criteria

From the literature, this study identifies several key criteria essential for achieving social sustainability in urban environments. These criteria are directly influenced by the interaction between physical and perceived density:

• Inclusivity: This is the ability of urban environments to provide equal opportunities for all community members, regardless of their socio-economic background. Inclusivity is supported by diverse housing options and equitable access to amenities and services [28].
• Community engagement: This is the level of resident participation in planning and decision-making processes. Community engagement is enhanced by accessible public spaces and amenities that encourage social interaction and collective involvement [29].
• Quality of life: Overall well-being, including health, housing satisfaction, and access to essential services, is a crucial component of social sustainability. Quality of life is influenced by the availability of green spaces, the design and layout of urban environments, and the effective management of density [21,24].
• Cultural diversity: This is the extent to which cultural diversity is embraced and promoted within the community. Cultural diversity is supported by inclusive urban design that reflects the values and identities of diverse population groups [8].
• Social cohesion: The strength of social bonds and a sense of belonging and security among residents are critical for social sustainability. Social cohesion is fostered by well-designed public spaces that encourage positive social interactions and community building [8,9].

5. Implication of Findings

The analysis of urban density and its implications for social sustainability yields several significant findings that enhance the understanding of how various forms of density impact social outcomes. This discussion interprets these results in the context of the existing literature, particularly in relation to the social sustainability indicators identified in this study. It also explores the relationship between physical and perceived density and how these factors interact to influence social sustainability in urban environments.

5.1. The Impact of Density on Social Sustainability

Through the literature, it is clear that understanding the intricate relationship between urban density and social sustainability involves analyzing how both physical and perceived density impact criteria like residents’ quality of life, inclusivity, community engagement, cultural diversity, and social cohesion. So, there is a need to explore the main criteria of social sustainability.

5.1.1. Criteria for Assessing Social Sustainability

Understanding the relationship between urban density and social sustainability requires a detailed examination of specific criteria that determine social outcomes in high-density environments. This section integrates the findings from the literature review with the key indicators of social sustainability, shown in Figure 2, namely inclusivity, community engagement, quality of life, cultural diversity, and social cohesion.

• Inclusivity: The literature underscores the importance of designing urban environments that offer equal opportunities for all community members, regardless of socio-economic background. Inclusivity is enhanced when affordable housing is integrated into high-density areas, along with accessible public spaces that foster social equity [2,28]. Churchman [4] notes that unmanaged increases in population density can exacerbate social tensions if urban spaces do not adequately address inclusivity, highlighting the need for thoughtful urban planning that prioritizes equal access to resources and services.
• Community engagement: Effective community engagement is critical for achieving social sustainability in dense urban settings. The literature highlights the role of well-designed public spaces in facilitating resident participation in planning and decision-making processes [9,29]. Woodcraft et al. [8] emphasize that urban environments that encourage community interaction and cultural diversity contribute significantly to social cohesion. Our findings align with this perspective, showing that integrated public spaces enhance community engagement, thereby reinforcing the social fabric of high-density areas.
• Quality of life: Quality of life is a multifaceted concept influenced by factors such as health, housing satisfaction, and access to essential services. The literature suggests that high-density urban environments can support a high quality of life if they include well-designed green spaces and accessible amenities [1,2]. Forsyth [5] notes that while high density can reduce land consumption and support sustainable transportation systems, it is crucial to balance these benefits with the provision of livable spaces that enhance residents’ overall satisfaction. Our study confirms that managing density through thoughtful urban design can mitigate potential negative impacts, thereby improving quality of life.
• Cultural diversity: Cultural diversity plays a vital role in fostering social cohesion within high-density urban areas. The literature demonstrates that urban design that embraces cultural diversity leads to vibrant, multicultural neighborhoods [8,29]. Our findings support this view, indicating that urban environments that promote cultural interaction and inclusivity are more likely to achieve social sustainability. This aligns with Healey [29] and Woodcraft et al. [8], who argue that culturally diverse urban designs contribute to stronger community bonds and resilience.
• Social cohesion: Social cohesion, defined by the strength of social bonds and the sense of belonging among residents, is crucial for social sustainability. The literature suggests that well-designed public spaces that facilitate positive social interactions are key to enhancing social cohesion in high-density environments [9,10]. Dempsey et al. [11] highlight that public spaces that encourage frequent and meaningful social interactions can alleviate the potential downsides of high density, such as feelings of overcrowding and isolation. Our findings resonate with this perspective, showing that urban spaces designed to foster social interaction contribute significantly to an overall sense of community and well-being.
• To further elucidate the relationship between the discussed social sustainability indicators and urban density, Figure 3 present a comprehensive framework that illustrates how physical and perceived density interact with these indicators.

5.1.2. Impact of Physical Density on Resident Perception

Through a comprehensive review of the literature, it is evident that physical density significantly influences how residents perceive their living environment. Several factors come into play when considering the impact of physical density on perception:

• Building height and spacing: Tall buildings and closely spaced structures often create a sense of enclosure, leading to perceptions of overcrowding and reduced personal space. The literature indicates that areas with taller buildings tend to feel denser, affecting residents’ mental well-being and satisfaction [12]. Similarly, narrow streets and dense building arrangements could create a feeling of high spatial density, impacting the perception of openness [31].
• Population and residential density: High population and residential density can enhance urban efficiency but may also contribute to perceived crowding if not balanced with adequate infrastructure and amenities. Studies have shown that high population density can enhance urban efficiency by reducing per capita land consumption and supporting sustainable public transportation systems [1]. However, there is also the potential for overcrowding and stress on public services if high density is not managed properly [4].
• Floor Area Ratio (FAR) and Building Coverage Ratio (BCR): Higher FAR and BCR values indicate more intensive land use, which can impact residents’ perception of their living conditions. The studies suggest that while higher FAR values can support urban density by reducing urban sprawl, they can also lead to reduced access to sunlight and ventilation, affecting environmental quality [21].
• Design and layout of urban spaces: Well-designed public spaces and green areas can mitigate the negative impacts of high physical density. Researchers argue that high-density urban spaces need to be designed thoughtfully to ensure comfort and privacy, significantly affecting how residents perceive density [24,36].
• Resilience/adaptability: Resilience refers to the ability of urban systems to accommodate changes and unexpected events, such as natural disasters or rapid population growth, without adversely affecting quality of life. High resilience in urban environments fosters a sense of security and stability among residents, positively impacting their perceptions of density. Studies suggest that resilient urban systems can reduce the stress associated with high density and contribute to improved social interaction and community integration [15].
• Access to amenities and services: When residents have easy access to essential services such as shops, schools, healthcare, and recreational facilities, their perceptions of the urban environment are significantly enhanced. Research indicates that good access to these services reduces perceived overcrowding and improves comfort and quality of life [9,19].
• Figure 3 shows the role of physical density parameters such as building height, spacing, population density, and urban design in shaping resident perceptions.

Figure 3. The role of physical density parameters in shaping resident perceptions.

Figure 3. The role of physical density parameters in shaping resident perceptions.

5.1.3. Impact of Perceived Density on Social Sustainability

The literature indicates that perceived density refers to the subjective experience of how crowded an area feels, influenced by visual, functional, social, and spatial factors. This perception significantly affects inclusivity, community engagement, quality of life, cultural diversity, and social cohesion, as shown in Figure 4. So, the main dimensions of perceived density are as follows:

• Visual density: This means the aesthetics and design of buildings and urban spaces. Studies have shown that areas with well-maintained green spaces, attractive architecture, and thoughtful urban design are perceived as less dense, even if they have high physical density [7]. This can lead to improved mental well-being and greater satisfaction within the living environment [31]. Additionally, elements such as building facades, street furniture, and public art contribute to a visually stimulating environment, which can positively influence residents’ perceptions [12].
• Functional density: This means the concentration of amenities and services within walking distance. High functional density means that residents have easy access to essential services such as grocery stores, schools, healthcare facilities, and recreational areas. Studies indicate that when these amenities are within close proximity, it reduces perceived distance and enhances the sense of convenience and livability [33,38]. Furthermore, mixed-use developments that integrate residential, commercial, and recreational spaces create a dynamic urban environment that fosters social interactions and community engagement [21]. Additionally, the integration of affordable housing within these areas is crucial. Affordable housing options help prevent socio-economic segregation by allowing residents from diverse income levels to live close to essential services and amenities. This integration supports a more inclusive community, enhancing social cohesion and promoting a balanced urban environment [28,29].
• Social density: This means the number of social interactions in public spaces. Well-used public spaces that support positive social interactions can enhance community cohesion and improve perceptions of high density. Areas with active public spaces, such as parks, plazas, and community centers where people can gather, socialize, and participate in communal activities, are perceived more positively [9,10]. Social density that promotes inclusivity and diversity can mitigate feelings of isolation and alienation, contributing to a sense of belonging and community well-being [8]. Furthermore, cultural diversity within these spaces plays a key role in enriching community life. Diverse cultural backgrounds contribute to vibrant social interactions, strengthening social bonds and enhancing an overall sense of belonging and resilience in high-density environments [8,29].
• Spatial density: This means the layout and connectivity of streets and open spaces which impact the perception of openness or confinement in urban areas. The literature shows that proper spatial planning, including well-connected streets and sufficient open spaces, can mitigate negative perceptions of high density. Urban layouts that prioritize pedestrian pathways, open plazas, and interconnected green spaces help create a sense of openness and freedom of movement [7,39]. Conversely, areas with poorly connected streets, a lack of public spaces, and limited green areas can feel congested and claustrophobic, negatively affecting residents’ perceptions and quality of life [36].

5.2. Conceptual Model of the Impact of Density on Social Sustainability

This section presents a detailed model illustrating how density impacts social sustainability. The model integrates both physical and perceived density factors and outlines their interactions with the social sustainability criteria. The relationship between density and sustainability can be understood in two stages, as shown in Figure 5: first, the impact of physical density on perceived density, and second, the impact of perceived density on social sustainability.

• Impact of physical density on perception: Physical density factors, such as building height and population density, influence residents’ perceptions of their environment. For example, taller buildings and higher population densities can create a sense of overcrowding, reducing personal space and impacting mental well-being.
• Mediating role of perceived density: Perceived density can either mitigate or exacerbate the effects of physical density on social sustainability. For instance, green spaces and aesthetically pleasing urban designs can improve environmental perception and reduce the negative impacts of high physical density. On the other hand, poor design and a lack of amenities can intensify the negative perception of density, leading to lower quality of life and social cohesion.
• Impact on social sustainability: The integrated effects of physical and perceived density influence the social sustainability criteria. Positive perceptions of density, supported by good urban design and community amenities, can enhance social cohesion, inclusivity, and quality of life. Conversely, negative perceptions can lead to social fragmentation, reduced quality of life, and decreased social capital.

The relationship between physical density, perceived density, and social sustainability is multifaceted, involving both direct and indirect interactions. The nature of these relationships can be parallel, where multiple factors contribute independently to social sustainability outcomes, or intersecting, where the effect of one factor depends on the presence or extent of another.

Physical density factors such as building height, population density, and the Floor Area Ratio (FAR) directly influence residents’ perceptions of their environment. For example, taller buildings and higher population densities create a sense of enclosure, which can reduce personal space and negatively impact mental well-being. This perception then indirectly affects social sustainability by influencing community engagement and quality of life.

Perceived density factors including visual, functional, social, and spatial perceptions, are shaped by physical density and have a direct impact on social sustainability. For instance, well-designed urban spaces with green areas are perceived as less dense, improving residents’ satisfaction and promoting social cohesion.

To clarify these relationships further, Table 8 illustrates the specific types of relationships (direct or indirect) and their nature (parallel or intersecting) between the various factors of physical and perceived density and their influence on the social sustainability criteria. This comprehensive framework highlights how different urban design elements interact to shape sustainable urban environments.

Table 8. Factors of physical and perceived density that influence social sustainability criteria.

Physical Factor	Influence on Perceived Density	Impact on Social Sustainability Criteria	Type of Relationship	Nature of Impact
Building Height	Visual perception of enclosure	Quality of Life, Public Spaces, Social Interaction	Direct	Parallel
Spacing	Feeling of openness or congestion	Quality of Life, Public Spaces, Social Interaction	Direct	Parallel
Population Density	Crowding perception, infrastructure demand	Inclusivity, Quality of Life, Community Engagement	Indirect	Intersecting
Residential Density	Crowding perception, infrastructure efficiency	Inclusivity, Quality of Life, Community Engagement	Indirect	Intersecting
FAR (Floor Area Ratio)	Land use intensity, environmental quality	Quality of Life, Public Spaces	Direct	Parallel
BCR (Building Coverage Ratio)	Land use intensity, environmental quality	Quality of Life, Public Spaces	Direct	Parallel
Urban Design	Comfort, privacy, visual appeal	Quality of Life, Cultural Diversity, Public Spaces	Direct	Intersecting
Building Design and Aesthetics	Visual density, attractiveness	Quality of Life, Cultural Diversity	Direct	Parallel
Green Spaces and Landscaping	Visual relief, reduced crowding	Quality of Life, Public Spaces	Indirect	Intersecting
Availability of Amenities	Functional density, convenience	Inclusivity, Quality of Life, Community Engagement	Direct	Parallel
Accessibility to Services	Functional density, livability	Inclusivity, Quality of Life, Community Engagement	Direct	Parallel
Public Space Usage	Social density, vibrancy	Community Engagement, Social Interaction	Direct	Parallel
Community Activities	Social density, cohesion	Community Engagement, Social Interaction	Direct	Parallel
Street Layout and Connectivity	Navigability, perceived congestion	Quality of Life, Public Spaces	Direct	Intersecting
Open Spaces	Reduced perceived density, recreation	Quality of Life, Public Spaces	Direct	Intersecting

Direct: the factor has an immediate impact on social sustainability without intermediary variables. Indirect: the factor influences social sustainability through one or more intermediary variables. Parallel: multiple factors independently contribute to the outcome without influencing each other. Intersecting: the impact of one factor is influenced by the presence or extent of another factor.

Table 8. Factors of physical and perceived density that influence social sustainability criteria.

Physical Factor	Influence on Perceived Density	Impact on Social Sustainability Criteria	Type of Relationship	Nature of Impact
Building Height	Visual perception of enclosure	Quality of Life, Public Spaces, Social Interaction	Direct	Parallel
Spacing	Feeling of openness or congestion	Quality of Life, Public Spaces, Social Interaction	Direct	Parallel
Population Density	Crowding perception, infrastructure demand	Inclusivity, Quality of Life, Community Engagement	Indirect	Intersecting
Residential Density	Crowding perception, infrastructure efficiency	Inclusivity, Quality of Life, Community Engagement	Indirect	Intersecting
FAR (Floor Area Ratio)	Land use intensity, environmental quality	Quality of Life, Public Spaces	Direct	Parallel
BCR (Building Coverage Ratio)	Land use intensity, environmental quality	Quality of Life, Public Spaces	Direct	Parallel
Urban Design	Comfort, privacy, visual appeal	Quality of Life, Cultural Diversity, Public Spaces	Direct	Intersecting
Building Design and Aesthetics	Visual density, attractiveness	Quality of Life, Cultural Diversity	Direct	Parallel
Green Spaces and Landscaping	Visual relief, reduced crowding	Quality of Life, Public Spaces	Indirect	Intersecting
Availability of Amenities	Functional density, convenience	Inclusivity, Quality of Life, Community Engagement	Direct	Parallel
Accessibility to Services	Functional density, livability	Inclusivity, Quality of Life, Community Engagement	Direct	Parallel
Public Space Usage	Social density, vibrancy	Community Engagement, Social Interaction	Direct	Parallel
Community Activities	Social density, cohesion	Community Engagement, Social Interaction	Direct	Parallel
Street Layout and Connectivity	Navigability, perceived congestion	Quality of Life, Public Spaces	Direct	Intersecting
Open Spaces	Reduced perceived density, recreation	Quality of Life, Public Spaces	Direct	Intersecting

Direct: the factor has an immediate impact on social sustainability without intermediary variables. Indirect: the factor influences social sustainability through one or more intermediary variables. Parallel: multiple factors independently contribute to the outcome without influencing each other. Intersecting: the impact of one factor is influenced by the presence or extent of another factor.

The effects of density factors on the social sustainability criteria can be explained by the following:

• Building height and spacing: » Influence how enclosed or open an area feels, affecting perceptions of crowding. » Impact quality of life by determining access to light and air and providing space for social interactions.
• Population and residential density: Higher densities can » lead to perceptions of crowding if infrastructure does not match the demand. » Affect inclusivity and quality of life by influencing housing availability and community services.
• Floor Area Ratio (FAR) and Building Coverage Ratio (BCR): High FAR and BCR values » indicate intensive land use » impacting environmental quality and perceived crowding. If properly managed, they » can support efficient land use, enhancing quality of life and access to public spaces.
• Urban design: Well-designed urban spaces can » mitigate the negative perceptions of high density by providing comfort and aesthetic appeal » and promote cultural diversity and social interactions through inclusive design.
• Building design and aesthetics: » Influence visual density and the attractiveness of the area. » Contribute to quality of life by creating aesthetically pleasing environments.
• Green spaces and landscaping: » Provide visual relief and reduce perceptions of crowding. » Enhance quality of life by offering recreational spaces and improving environmental quality.
• Availability of amenities and accessibility to services: High functional density » improves convenience and livability. » Support inclusivity and community engagement by ensuring access to essential services.
• Public space usage and community activities: » Influence social density and community cohesion. » Foster social interactions and community engagement by providing venues for social activities.
• Street layout and connectivity: » Influence navigability and perceptions of congestion. » Enhance quality of life by improving accessibility and reducing travel times.
• Open spaces: » Reduce perceived density by providing areas for relaxation and recreation. » Enhance quality of life and support social interactions in public spaces.

6. Discussion and Conclusion

6.1. Challenges and Comparisons with the Existing Literature

One of the main challenges was synthesizing a vast array of studies, each with different methodologies, theoretical perspectives, and contextual focuses. The goal was to extract relevant insights into how urban density, both physical and perceived, impacts social sustainability. The diversity of the literature meant that the findings often varied significantly depending on the context of the study, such as geographic location, cultural factors, and the specific aspects of density being examined. This required a careful balancing act to ensure that the final selection of 41 articles provided a comprehensive yet focused understanding of the topic.

In comparing the findings from this study with the existing literature, several important observations were made. While the broader literature, such as works by Newman and Kenworthy (1999) and Burton (2000), has consistently highlighted the environmental and economic benefits of high physical density [1,2], this study delved deeper into the social dimensions, particularly how perceived density shapes social sustainability outcomes. The existing literature often treats physical and perceived density separately, but this study emphasized their interrelationship, revealing that residents’ perceptions of density—shaped by factors like building design, availability of green spaces, and social interactions—are critical in determining social outcomes such as community cohesion and quality of life.

Another challenge was integrating findings across different contexts and theoretical frameworks into a single, coherent conceptual model. The existing literature often addresses urban density from specific regional or cultural perspectives, which may not always align. This study sought to bridge these gaps by developing a model that could be applied more universally, while still accounting for local variations. For instance, the study found that in some contexts, high density was associated with positive social outcomes due to well-designed public spaces and community amenities, whereas in others, it led to social fragmentation and decreased quality of life.

6.2. Conclusions

This article delves into the relationship between urban density and social sustainability by examining both physical and perceived density and their impacts on key social sustainability criteria. The interplay between physical and perceived density significantly influences residents’ experiences and satisfaction. Physical density, with attributes such as building height, spacing, population density, and urban design, sets the structural foundation of urban environments. However, perceived density—shaped by visual, functional, social, and spatial factors—ultimately affects how dense an area feels to its residents.

Ensuring inclusivity through affordable housing and diverse housing options, fostering community engagement, and enhancing quality of life with well-designed public spaces and green areas can support social sustainability. Promoting cultural diversity and social cohesion through spaces that support social interactions and community activities is also essential.

Key factors influencing perceptions of density include building design, green spaces, amenities, and the layout and connectivity of urban spaces. These factors influence both the visual appeal and the functional and social vibrancy of urban environments. Thoughtful integration of these elements can mitigate negative perceptions of high density and enhance overall quality of life.

To achieve social sustainability in urban environments, urban planners and policymakers need to carefully consider the interplay between physical and perceived density. Giving priority to green spaces, public areas, and community amenities, along with inclusive planning processes, can lead to more livable, equitable, and resilient urban environments. This article provides a framework for understanding these complex relationships and offers insights for creating cities that are efficient, environmentally sustainable, inclusive, vibrant, and supportive of residents’ well-being.

Furthermore, future research should explore the dynamic interplay between physical and perceived density over time, particularly through longitudinal studies that can track how these factors evolve and impact social sustainability in diverse urban contexts. There is also a need for empirical validation of the conceptual model proposed in this study, which could be tested across different cultural and socio-economic settings to enhance its applicability and relevance. These directions for future research will help in further refining the understanding of urban density’s role in shaping socially sustainable cities.