High-density Urban Environment Research Articles

Optimizing Built Environment in Urban Negative Spaces Using Parametric Methods—Research on a High-Density City in China

In the early stage of architectural design, addressing the challenges posed by negative spaces in high-density urban environments is crucial for enhancing spatial efficiency and building sustainability. Multiple studies employed digital methods and tools to address these issues, such as parametric design, simulation, and genetic algorithms, to investigate architectural generation approaches for urban negative spaces. This article proposes an integrated design process that involves finding the location and form of negative spaces, generating solutions using slime mold and wasp algorithms, and optimizing and analyzing solutions using the Wallacei plugin in Grasshopper. This comprehensive approach underscores the potential of parametric design to yield a multitude of solutions while also acknowledging the convergence challenges encountered during simulations, particularly in optimizing for optimal sunlight exposure during the winter solstice and minimal solar radiation in the summer. Analyzing the optimization goals and parameter values of the 15th Pareto optimal solution in the 100th generation reveals: (1) a higher number of units leads to positive correlation growth in both objectives; (2) within a certain number of units, parametrically generated solutions facilitate the convergence of optimization goals, yielding optimal outcomes. Therefore, factors such as the range of unit quantities and proportions need consideration during early-stage parametric design and simulation. This study explores a design methodology for negative spaces in high-density urban cities, validating the feasibility of various mainstream generation methods and offering insights for future research.

Unveiling the magic of mega-city block environments: investigating the intriguing mechanisms shaping children's spontaneous play preferences.

This study delves into the spatial preferences of children for play spaces within high-density urban block environments, specifically targeting the area of Baihua Second Road in Shenzhen, China. Recognizing the critical role of play in children's development, and the unique challenges posed by dense urban settings, this research employs multiclass logistic regression models and negative binomial regression models to construct a detailed mathematical analysis of neighborhood spatial elements and children's play space preferences. Data was meticulously gathered through both objective observations of 14 different types of spaces within the block, and subjective assessments via children's responses to a series of environment photos, capturing the essence of over 3,000 child participants' interactions and choices. Key findings reveal a pronounced preference among children for soft facility features and visually appealing spatial experiences, suggesting a nuanced understanding of play space needs beyond traditional playground designs. Notably, the study identifies that while cartoon-style designs in play facilities might increase moderate attractiveness, ordinary designs hold broader appeal, indicating a preference for diversity in play space aesthetics. These insights offer profound implications for urban planners and designers, advocating for a child-centered approach in the creation of urban play environments that prioritize aesthetic diversity, and the integration of natural elements. Moreover, the study situates Baihua Second Road as a paradigmatic case, illustrating the methodology and analytical framework applied in addressing the complex interplay between children's play preferences and urban spatial configurations. By incorporating a comprehensive data-driven analysis, this research contributes significantly to the discourse on child-friendly urban design, offering valuable strategies for cultivating inclusive and engaging urban play spaces for children amidst the constraints of high-density city living.

Exploring the combined cooling effect of street canyon geometry and the surrounding built environment.

Exploring the impact of complex urban morphology on the urban heat island (UHI) effect is essential for sustainable environmental management and enhancing human well-being. This study explored the combined cooling effect of street canyon geometry and the surrounding built environment using a CatBoost model and the Shapley method. The findings indicated that in streets with low building height and density, a high proportion of sky and vegetation and a flatter skyline are conductive to mitigate UHI effect. In streets with high building height and density, a lower proportion of sky and vegetation, and a well-proportioned skyline, can effectively mitigate UHI effect. Regardless of the building density and height around the street, street trees are the optimal choice for greening construction and improvement of large and medium-sized cities in China, given their high controllability and the current urban stock background. Therefore, reasonable control and allocation of street trees can effectively adjust the street canyon geometry, providing suitable cooling strategies for streets with different surrounding built environments. This study proposed a method to mitigate the UHI effect through street canyon geometry, which can be extended to other high-density urban thermal environment studies and guide policymakers on street construction and urban design.

Modeling the long-range transmission of airborne bioaerosol releases in a high-density urban environment

In this study, the effect of different meteorological conditions in four seasons on the flow field in a high-density urban environment was examined using numerical simulations. The effect of different thermal conditions on bioaerosol dispersion was evaluated. The dispersions of bioaerosol under three leakage scenarios, i.e., far from crowds (Release 1), close to crowds (Release 2), and simultaneous leakage at two locations, were analyzed. The flow field analysis shows that the wind speed is higher during the summer solstice than the other dates in the vertical direction. The concentration field analysis shows that compared with stable thermal conditions, the lateral dispersion range of bioaerosol in unstable thermal conditions is smaller and the dispersion distance is longer. Compared to Release 2, the Release 1 condition exhibits narrower lateral dispersion. In simultaneous releases, while the vertical concentration distribution trends remained unchanged, there were notable variations in concentration levels and dispersion range. The deposition analysis shows ground deposition in building areas surpasses building wall surface deposition across diverse leakage scenarios and meteorological conditions. Additionally, in Release 1, unstable thermal conditions enhance bioaerosol deposition on building walls but reduce it on the ground within the building area, compared to stable thermal conditions.

A distributed route network planning method with congestion pricing for drone delivery services in cities

Unmanned aerial vehicle (UAV)-based commercial services, exemplified by drone delivery, have captured wide interest in tech companies, entrepreneurs, and policymakers. Structured route-based UAV operations have been implemented for traffic management of UAVs in support of commercial delivery services in cities. Yet, its essence, multi-path planning with constraints is not well solved in the existing literature. Centralized planning might result in inefficiencies and unfairness in the allocation of precious urban airspace to individual routes. This paper describes a novel distributed route planning method to support UAV operations in a high-density urban environment. The method allows each origin–destination (OD) pair to compete against other OD pairs for an optimized route (e.g. shortest distance), coordinated by a system-level evaluation, leading to a network design that maximizes the performance of not only the individual routes but also the entire system. The core concept is the introduction of congestion pricing, a soft constraint to coordinate the allocation of airspace. The method is tested in standard 2D scenarios and compared with other state-of-the-art methods. The results show that (1) the method is able to generate routes with short individual distances as well as occupying the least airspace by the route network; (2) in some complex scenarios, the method is able to find a solution in a short period of time while other state-of-the-art method fails. The method has also been applied to a real urban environment (Mong Kok in Hong Kong) to demonstrate its capability.

The Mechanism of Street Markets Fostering Supportive Communities in Old Urban Districts: A Case Study of Sham Shui Po, Hong Kong

In old urban districts with tenement buildings, street markets address the working class’s social and economic needs. They are pivotal in fostering supportive communities, in particular for low-income residents in sub-standard housing. However, their outdated overall environment impedes the delivery of adequate support to residents. Prior research on street markets has focused on those in the Americas and Europe, and has revealed the societal support values of these markets. However, studies on street markets in high-density cities like Hong Kong are lacking. This study introduces an evaluation framework to assess the impact of street markets on the development of supportive communities for Hong Kong’s sub-divided apartment residents. Employing the Pei Ho Street market in Sham Shui Po as a case study, an importance-performance analysis highlights critical but underperforming factors including public facilities, activity venues, commerce, and employment. Based on these findings, the study proposes four improvement strategies for the renewal of street markets in high-density communities, which could apply to other cities with similar high-density urban environments. It concludes that street markets in Hong Kong display unique spatial characteristics shaped by low-income lifestyles in a high-density urban environment, enriching daily social life and promoting sustainable community development.

Designing for health: A study of architecturally oriented models of public space

AbstractIn the post-pandemic period, cities are committed to creating healthier and more healing urban environments. In high-density urban environments, urban complexes are increasingly assuming the function of enriching the external space and activating the vitality of cities, and their architecturally oriented public spaces have great potential for the promotion of residents' health. However, current research on public space and health has focused on green spaces and neighborhoods, and has not yet systematically sorted out the pathways that influence how building-oriented public space can contribute to health. In order to fill the gap, this study attempt to establish a model of health-promoting architecturally oriented public space, which can provide a reference for the similar projects.

Combining Pocket Parks with Ecological Rainwater Management Techniques in High-Density Urban Environments

In this paper, the benefits of combining pocket parks with Sustainable Drainage Systems (SuDS) in densely built urban areas are demonstrated, through an application proposal in a medium to low-income neighborhood of the historical center of Thessaloniki, Greece. After an outline of the urbanization impact upon rainwater management, the features of the proposed site are presented, in particular those related to rainwater runoff (e.g., rather large ground slope, narrow sidewalks), which result in considerable nuisance, even during medium intensity rainfall events. The choice of the SuDS components, namely a small-scale rain garden and a permeable pavement zone is explained next. Then, the basic design details of the proposed rain garden are given, including the form of the inlet structures and a list of plants, suitable for the climatic conditions of many North Mediterranean regions. The role and the features of the permeable pavement zone are also discussed and some ideas for the urban equipment required to upgrade the park are presented. A preliminary estimate of the cost for the construction of the rainwater management works and for upgrading the available lot to a pocket park is also included. Compared to the cost of sewer pipe network reconstruction, it can be concluded that the proposed solution is cost-efficient, even without considering aesthetic and social benefits. Moreover, it allows for stepwise construction, based on the available funds.

Failed pedestrian street experiments in high-density urban Asia: A matter of policies?

Promoted by sustainable urban agendas and urged by global pandemic measures, street experiments (SE) are booming in Europe but remain latent in Asia. These experiments aim to reconfigure streets as more than spaces for motorized traffic movements, enabling a temporary urban paradigm shift. Such a shift involves balancing active mobility and public space uses in streets while envisioning radically different settings and uses. Recently, eminent scholars urged considering SE in connection to the system and planning framework within which SE are conceived to trace their trajectories. This article examines four decades of temporary-pedestrianization policies and planning instruments in Hong Kong, an Asian city representative of high-density urban environments with highly intensive use of road space and conservative and prescriptive planning. In doing so, the article identifies four trajectories and illustrates two emblematic cases: Chater Road, the first street temporarily pedestrianized under a commercial initiative, and Sai Yeung Choi Street South, a street pedestrianized under a government initiative, now turned back to its original function. The competing roles and practical uses that pedestrianized streets must fulfil partially determined their fate. However, the trajectories these cases followed also differ due to the contextual planning approach and decision-making process. The study contributes to scholarship on SE by shedding new light on the geographical context of high-density urban Asia, forwarding challenges that policymakers might need to address in the planning and governance of SE in similar environments.

Impact of Physical Environmental Factors on Mental Wellbeing of Condominium Dwellers

This paper attempts to reveal the outcomes of the empirical research investigating how the physical environments of the residential high-rises, known as condominiums, including the urban and community contexts, impact mental wellbeing of the dwellers since the emergence of condominiums in Bangkok’s real estate market has continued to proliferate. The principal objectives of the research are to determine the assumption that the high-density urban environment and unique structure of condominiums are the significant determinants affecting occupants’ mental status. Based on the quantitative research approach, the two-stage stratified sampling technique and a cross-sectional survey were performed to engage 1,206 participants from eighteen high-rise condominiums in Bangkok. The interdisciplinary research instruments applied in this study are a Physical-Environmental (PE) Assessment for evaluating the physical environment and surroundings of the condominiums and a Personal and Psychological (PP) Questionnaire for collecting respondents’ attributes and their psychological status quo: safety concerns, privacy satisfaction, and a sense of community at the time of their dwelling in condominiums. At the analytical stage, three inferential statistics, Pearson product-moment correlations, independent sample t-test, and one-way analysis of variance, were applied at the p-value ≤ 0.05. The results endorsed three urban factors: geographical zoning, land use zoning, and density of population as significant dominants of safety concerns, including the sense of community of condominiums’ dwellers, whereas community and architectural factors appeared to have distinctive effects on all three psychological variables.

Modeling walking accessibility to urban parks using Google Maps crowdsourcing database in the high-density urban environments of Hong Kong

Accessing urban parks is important for promoting physical activities and improving public health. In this study, we propose the use of Google Maps crowdsourcing data and the incorporation of park attractiveness to model urban park accessibility in the complex urban environments of Hong Kong. The difference between using geometric and route distance, the effect of park attractiveness in measuring accessibility, and the benefits gained from using walk time compared to distance are investigated. Our result shows that (1) route and geometric distances have a strong correlation with a conversion factor of about 1.5; (2) the common assumption that park size can be a proxy for describing attractiveness may not be correct. Instead, park attractiveness should be explicitly considered for a more effective accessibility modeling; and (3) estimation by walking time shows that there are non-negligible impacts from street conditions and traffic on urban park accessibility. Moreover, district hotspots short of park accessibility or attractiveness can be explicitly detected. Overall, this developed approach provides a flexible and informative approach to model the accessibility to urban parks. The outputs will help city planners, health professionals, and policymakers to evaluate and improve urban park planning and equity in accessibility in high-density cities.

Hong Kong kindergartens in urban space: policy aspirations, historical trajectories, and contemporary disparities

ABSTRACT This paper investigates problems of space in Hong Kong kindergartens. It reports survey findings of a policy study relating to the Kindergarten Education Scheme (KES). KES emphasizes holistic development and child-centred pedagogy, which require larger and more flexible spaces than traditional desk-based learning. The study aimed to explore kindergartens’ responses to the resulting challenges around providing adequate space within Hong Kong’s high density urban environment. Questionnaires were sent to principals of 751 KES kindergartens. 325 valid questionnaires were collected (response rate: 43.5%). Analysis comprised descriptive statistics, inferential tests of relationships between operation mode and other variables, and coding of open-ended question responses. The paper highlights three key findings: (i) kindergartens reported a wide range of challenges relating to space; (ii) most augment their provision by using public spaces outside the premises, but these spaces come with their own challenges; and (iii) there were significant differences in the extent of reported problems between kindergartens operating in different modes, with long-whole-day kindergartens experiencing greater difficulty and disparity. Situating these findings in the historical context of Hong Kong’s uneven urban development, we argue that policy improvement of spatial provision will require reducing pressures on kindergarten spaces, rather than merely setting out spatial standards.

Impacts of green-blue-grey infrastructures on high-density urban thermal environment at multiple spatial scales: A case study in Wuhan

Land surface temperature (LST) has been broadly applied to urban climate studies. However, the sensitivity of LST to urban green-blue-grey infrastructures (GBGI) is still not clear, particularly at multiple spatial scales. A case study at a high-density area in Wuhan investigated the impacts of 27 indicators, including area proportion (AP), plot ratio (PR), and landscape fragmentation index (LFI), on LST at ten different spatial scales. The effects of individual and combined GBGI characteristics on LST were examined with correlation tests and multiple regression models, respectively. In single-factor test, LST is most sensitive to blue infrastructure (BI) and grey infrastructure (GYI) at 1600 m. BI_AP, BI_PR, River_AP, GYI_AP, Pavement_AP, and Building_AP showed strong correlations with LST at all scales. Regarding GNI (green infrastructure), LST is the most sensitive to GNI_LFI and Woodland_LFI at 1600 m, while to GNI_AP and GNI_PR at 50 m. In the hybrid state, LST has the highest sensitivity to GBGI sub-components at the district scale (1200–1600 m) based on multiple regression models. Finally, we evaluated the efficiency of different GBGI-based strategies by comparing 12 designed scenarios. This study provides important references for selecting effective spatial scales and indicators to maximize cooling efficiency in urban climate research and planning.

Air pollution dispersion in Hail city: Climate and urban topography impact

Due to the rapid urbanization of many cities around the world, industrial manufacturing plants have been expanded quickly, leading to the discharge of large amounts of pollutants into the environment. Consequently, a significant deterioration in local air quality is recorded, representing a high health risk for the city's residents. In this context, the main objective of this work is to understand the dispersion of gas pollution in high-density urban environments, specifically the Hail region of Saudi Arabia. The simulations carried out with Ansys Fluent 19.0 were based on actual climatic conditions, with particular attention paid to accurately reproducing the exact topography of the study area. The main results concern the characterization of flow behavior and the dispersion of gas pollutants emitted by power plants. Several factors, including building geometry and wind speed, are examined. The study reveals that for a reference wind speed of more than 7 m/s, gaseous pollution exhibits a significant tendency to accumulate within buildings, resulting in significant concentrations.

Healthy Dwelling: The Perspective of Biophilic Design in the Design of the Living Space

As urbanization continues to advance rapidly, the emergence of biophilic design offers a positive perspective to address the alienation between humans and nature, becoming a hot research topic in areas related to human living environments. Biophilic design, as a design concept inspired by nature, has positive significance in promoting the development of ecological diversity and improving human physical and mental health. This paper makes a comparative analysis of two of China’s residential communities in the same high-density environment through the main influencing factors of plot ratio, greening rate, external facades environments, and internal living space. Starting from the five senses of the human body, namely, sight, hearing, touch, smell, and taste, this paper aims to investigate the design of living spaces through the lens of biophilic design, and proposes a biophilic design model, along with strategies and recommendations tailored to high-density urban environments, in the hope of serving as a valuable reference and source of inspiration for future healthy dwelling design.

The Impact of High-Density Urban Wind Environments on the Distribution of COVID-19 Based on Machine Learning: A Case Study of Macau

The COVID-19 epidemic has become a global challenge, and the urban wind environment, as an important part of urban spaces, may play a key role in the spread of the virus. Therefore, an in-depth understanding of the impact of urban wind environments on the spread of COVID-19 is of great significance for formulating effective prevention and control strategies. This paper adopts the conditional generative confrontation network (CGAN) method, uses simulated urban wind environment data and COVID-19 distribution data for machine training, and trains a model to predict the distribution probability of COVID-19 under different wind environments. Through the application of this model, the relationship between the urban wind environment and the spread of COVID-19 can be studied in depth. This study found that: (1) there are significant differences in the different types of wind environments and COVID-19, and areas with high building density are more susceptible to COVID-19 hotspots; (2) the distribution of COVID-19 hotspots in building complexes and the characteristics of the building itself are correlated; and (3) similarly, the building area influences the spread of COVID-19. In response to long COVID-19 or residential area planning in the post-epidemic era, three principles can be considered for high-density cities such as Macau: building houses on the northeast side of the mountain; making residential building layouts of “strip” or “rectangular” design; and ensuring that the long side of the building faces southeast (the windward side). (4) It is recommended that the overall wind speed around the building be greater than 2.91 m/s, and the optimal wind speed is between 4.85 and 8.73 m/s. This finding provides valuable information for urban planning and public health departments to help formulate more effective epidemic prevention and control strategies. This study uses machine learning methods to reveal the impact of urban wind environments on the distribution of COVID-19 and provides important insights into urban planning and public health strategy development.

Spatiotemporal characteristics of Chinese metro-led underground space development: A multiscale analysis driven by big data

Nowadays, the use of metro-led underground spaces (MUS) has become imperative in high-density urban environments. However, a comprehensive and systematic understanding of MUS development patterns in densely-populated countries like China is still lacking. Therefore, this study employed a data-driven spatiotemporal analytical framework based on multisource big data to investigate the development mechanism of Chinese MUSs using a full sample. The multiscale analysis, covering MUS, urban, and regional scales, was conducted to identify the driving forces of MUS development over five temporal stages. The results revealed that the development characteristics of Chinese MUSs varied across different spatiotemporal contexts. At the micro level, the primary driving factors, including density, diversity, distance to transit, and destination accessibility, had a strong explanatory power, which is consistent with the mainstream transit-oriented development (TOD) theory. At the macro level, the main drivers included economic factors, environmental factors, and development scale factors. This study provides new insights for MUS development in high-density regions worldwide, and the obtained regularities could be effectively adopted in the planning and design for MUS.

0367 Urban Stress and Sleep Health by Proximal Neighborhood Groups in Washington, DC

Abstract Introduction African Americans are disproportionately affected by environmental factors that increase the risk for negative health outcomes. Analyses from National Health Interview Survey (NHIS) data estimated 15 to 75 percent of the disparities between Black and White respondents being accounted for by residential context. Poor sleep health, particularly short sleep duration, has been linked to metabolic and cardiovascular disease. A population study indicated that sleep duration of less than 6 hours was more common among African Americans compared with other racial groups in the United States and this association was accounted for by African Americans living in high density urban environments. Threats of violence may engender feelings of vulnerability when sleeping and be an important determinant of sleep health though this relationship has not been adequately studied. The aim of this study is to determine how an individual’s sleep health relates to violent crime rates in their neighborhood of residence as well as indicators of neighborhood stress endorsed in a self-reported survey. Methods African- American men and women between the ages of 18-35 filled out the insomnia severity index (ISI) and city stress inventory (CSI). Sleep duration and sleep efficiency were obtained through home-based actigraphy. Participants were categorized as poor sleepers if two out of three criteria were met: sleep duration of less than six hours, ISI greater than 10, and sleep efficiency below 85%. Participants addresses were linked to one of the 51 proximal neighborhood groups (PNG) defined by the DC Department of Health and Office of Planning using MAR geocoder and QGIS mapping software. Violent death rates and other social health determinants are indicated by PNG in the DC DOH’s Health Equity Report (2019). Results Sleep measures were not correlated with neighborhood violent death rates (Pearson r’s: .05 - .17; all NS). SE and TST were weakly correlated with CSI scores (both r’s = -.22, NS). Conclusion The negative findings may be related to sample size, the presence of threat and crime in all of the locations, and the importance of individual coping. Support (if any) NIHLB grant R01HL136626 to Dr. Thomas A. Mellman and NCATS grant for a Clinical Translational Science Award UL1-TR001409.

Identification of source location in a single-sided building with natural ventilation: Case of interunit pollutant dispersion

A sudden outbreak of COVID-19 occurred in December 2019 and its rapid spread over the last two years caused a global pandemic. A special airborne transmission via aerosols called interunit dispersion is risky in a high-density urban environment, which needs more attention. In order to identify the source location of pollutants or viruses under the interunit transmission condition with natural ventilation, this study adopted the inverse Computational Fluid Dynamics (CFD) simulation with the adjoint probability method. The detailed process of the inverse modeling was presented. Also, the possible interunit transmission routes of the pollutants or viruses were analyzed. A three-story building model with single-sided openings was built. Six different combinations of fixed sensor locations were tested, and it was determined that setting sensors in the four corner regions of the building was the optimist strategy. A total of 25 cases with five different wind directions (0°, 45°, 90°, 135°, and 180°) were tested to verify the accuracy of the source location with inverse modeling. The results showed that 67%–78% of the rooms in the building can be identified with a limited number of pollutant sensors and all rooms can be identified with one additional sensor in the downstream room of the building under different wind direction. This research revealed that the inverse modeling method could be used to identify the pollutant source in the coupled indoor and outdoor environment. Further, this work can provide guidance for the pollutant monitor positions in the applications.

Benchmarking the sustainability of concrete and steel modular construction for buildings in urban development

The modular approach has been increasingly adopted for building projects. However, few previous studies investigated the performance of different modular construction systems and their impacts on urban development. This paper aims to contribute to a more systematic understanding of modular construction for buildings in high-rise high-density urban environment, through measuring the sustainability of both concrete and steel modular construction. The measurement was conducted using two real-life modular building projects in Hong Kong covering 11 indicators in environmental, social, and economic sustainability. Results reveal that modular construction significantly outperforms the conventional practice, e.g., 46%-87% of waste reduction thus reducing the burden of urban waste disposal. Nevertheless, performance of the steel modular system varies from the concrete one, e.g., being 40% faster thus more suitable for emergency project delivery, but 20% more of electricity consumption. From the discussion, eight system boundaries were identified for dialectical sustainability benchmarking, e.g., density boundary to indicate the project context; and systematic strategies were proposed for sustainability enhancement, e.g., design for circularity for temporary modular facilities. The paper should facilitate the selection of suitable modular systems by demonstrating the sustainability of different modular construction systems and contributing dialectical thinking to construction performance measurement.