To promote the effective combination of photovoltaic (PV) utilization and urban development, this study proposes that solar PV generation should be taken as an important resource and environmental carrying capacity factor, which is defined as “Photovoltaic Carrying Capacity (PVCC)”, to be integrated into future urban planning. According to the PVCC assessment on global cities, the sensitivity of PVCC to different influence factors is analyzed and the benefits of different optimization strategies on PVCC are also discussed. Additionally, in an equilibrium analysis of PVCC distribution in six sample countries, we discuss both the causes and impact of their distribution gap. That analysis shows that the average PVCC in global urban areas can reach 23.13%, which approaches the anticipated needs of PV development in cities by 2050.Though different optimization strategies may be feasible to promote urban PVCC, they might only make significant changes in medium or large cities. When considering the high-efficient utility of local energy, dispersed layout of cities and population is necessary to implement PV spatial planning. According to the assessment and analysis results, the adjustment suggestions of PV spatial planning in each sample country are also discussed. Finally, it is pointed out that the proactive PV spatial may be of great significance to achieve higher solar energy supply and PVCC will be an available cognition in guiding this planning in the future.

Against the background of rapid global urbanization, the renewal and renovation of historic districts have become an increasingly important concern. As a city with a long and rich history, Beijing contains numerous historic districts that are in urgent need of systematic renewal and renovation. This study proposes a functional enhancement and renovation design methodology for urban historic districts based on space syntax theory and analytical methods, applying it to the Qianmen Historic District in Beijing. Through traffic flow and business format analysis, the research examines traffic patterns and business format distribution characteristics in the Qianmen area and ultimately guides the design based on these findings. Research indicates that restrooms and attractions in Beijing’s Qianmen historic district exhibit dispersed space distribution, broad service coverage, high metric step depth (447 m and 436 m, respectively), and low topological connectivity. In contrast, hotels and restaurants feature smaller service areas, lower metric step depth (395 m and 297 m, respectively), and higher topological connectivity. Based on these findings, this study proposes targeted design recommendations for Qianmen’s street renovations based on traffic flow analysis results. Considering the need for vehicle parking and pedestrian rest demands in urban functional renewal, rest seats and shared charging piles are set up on the streets with big pedestrian flow to meet the needs of pedestrians. Moreover, cycling routes are designed to connect big-traffic-flow streets with small-traffic-flow ones. These renewal measures aim to enhance the overall vitality of the Qianmen district. The renovation approach and methodology proposed in this study can serve as a reference for future updates and renovations of historic districts.

Global urbanization and climate change are intensifying challenges in the sustainable management of the Food–Energy–Water (FEW) system. This study introduces a multi-objective optimization framework that redefines urban spaces through a dual rooftop-ground hierarchy, interlinkage nodes for mapping material and energy flows, and the application of NSGA-II optimization to balance food production, energy output, and costs. The framework was applied to a case study area, generating non-dominated solutions with diverse resource-cost configurations. The findings revealed that optimal scenarios could meet 40.6% of local energy demands and exceed 102.9% of local grain demands, while maintaining economic viability. This approach bridges resource systems theory and spatial planning practice, providing economically viable pathways for high-density cities to transform into hybrid production-consumption spaces, effectively addressing the dual pressures of urbanization and climate change.

In many highly dense urban environments, the urgent needs of residents for increasing green space, improving the quality of the community environment and reconstructing the relationships among residents have given birth to the new space type of community gardens. However, China still lacks this relevant experience. In contrast, New York City's community gardens had a relatively early start, and they now have rich experience in space construction, operation and maintenance. Given their level of experience, they can be used as references for the development of community gardens in China. This paper adopts a bibliometric research method, identifies 201 periodical literature sources published between 2000 and 2020 from the core library of the Web of Science as the object of study, and finally assesses the research hotspot for transferring from macro-research to space-type construction method, social impact, and so on, through CiteSpace software analysis. By virtue of the research process analysis and the results of field surveys and interviews, this paper probes the development status of space construction and social organization construction of the community gardens in New York City, and summarizes that area's effective experience of development. Based on the current development situation of China's community gardens, it is proposed that the development of community gardens should be directed by ensuring the land for development, giving full play to social benefits, and mobilizing social organizations, so as to effectively realize urban space construction and social governance.

Urban morphology is a critical determinant of photovoltaic (PV) potential in cities, yet current design practices rarely incorporate this relationship systematically. Existing studies often struggle to balance analytical precision with computational efficiency and to translate data-driven insights into practical design implementation, limiting the role of morphological optimization in zero-energy urban transitions. To address these challenges, this study develops a three-stage computational workflow: (1) a lightweight surrogate model that replaces computationally intensive physical simulations to efficiently quantify multidimensional morphological impacts on PV potential; (2) an optimization algorithm that integrates the surrogate model to identify optimal urban configurations; and (3) a design translation framework that converts analytical outputs into actionable planning strategies. A case study in Tianjin demonstrates the method’s effectiveness, identifying floor area ratio (FAR) as the most influential parameter (β = 0.969, p < 0.001) and deriving optimal morphological values (FAR = 4.02; Shape Coefficient = 0.23) which yield substantial PV potential improvements of 13.9%–56.9% in new developments and 8.0% in retrofit scenarios. This generalizable method offers planners and policymakers an evidence-based tool applicable across diverse urban contexts, advancing the integration of morphological and energy optimization in the pursuit of zero-energy cities.