Urban Science

Urban energy systems are expected to undergo a rapid transition towards smart, sustainable, and resilient infrastructures. Within this transformation, the interaction between smart buildings and energy grids plays a critical role in shaping future urban energy solutions. Smart building–grid interaction strategies facilitate the bidirectional energy flow between buildings and urban energy systems and support the integration of renewable energy sources (RESs) into cities’ energy systems through advanced control systems, sensing technologies, and digital infrastructures. However, the adoption of these solutions remains complex due to fragmented key performance indicators (KPIs) and the diversity of enabling technologies, and it requires accurate performance-driven design and operation. Despite recent advancements, the management and evaluation of the interaction of smart buildings and urban energy systems remain challenging due to overlapping and fragmented KPIs as well as the complexity of enabling technologies. Therefore, this study aims to review the recently published research works and provide a holistic taxonomy of KPIs and enabling technologies for such interplay between smart buildings and urban energy systems to achieve the goal of sustainable energy transition in cities. The study identifies and categorizes several existing KPIs across sustainability dimensions, including technical, environmental, economic, and social, covering the KPIs to measure the performance of smart building–urban energy systems from a sustainability-aware lens, offering an integrative framework for assessing urban energy resilience and efficiency. Additionally, the study contributes to classifying the enabling technologies for smart building and urban energy system interaction and discusses the interdependencies among such technology clusters. The findings contribute to ongoing urban energy transitions by promoting systemic approaches to planning, performance evaluation, and decision-making for sustainable and equitable urban energy futures. This contributes to the sustainability of the building and energy sectors at the urban scale by promoting and helping multi-dimensional performance assessment and informed decision-making.

Urban streams often suffer from poor water quality, in part due to nutrient pollution, especially in highly developed areas. Poor water quality, driven by high concentrations of nitrate and phosphate entering waterways from runoff, wastewater, and stormwater systems, contributes to urban stream syndrome. This study evaluates the long-term performance of a floating wetland (FW) system installed in a canal of the North Branch of the Chicago River near Goose Island, an area heavily impacted by urban runoff. From 2018 to 2023, surface and subsurface water samples were collected upstream and downstream of a 90 m² FW system and analyzed for nitrate as nitrogen (NO₃-N) and phosphate (PO₄³⁻) using ion chromatography. A paired t-test and two-way ANOVA revealed statistically significant reductions (p < 0.001) in NO₃-N (mean: 1.31 mg/L surface, 1.02 mg/L at 0.3 m) and PO₄³⁻ (mean: 0.64 mg/L surface, 0.57 mg/L at 0.3 m) between waters entering and exiting the FW, with no significant seasonal differences in removal efficiency. These results highlight the FW’s consistent, year-round nutrient mitigation performance driven by plant uptake and microbial processes. Over the five-year period of the study, the FW served as a means of improving the water quality, delivering a sustainable, low-maintenance solution for urban stream management with broader implications for ecological resilience and water quality enhancement.

This study examines how Bulgarian municipalities plan for disasters through the analysis of their municipal disaster protection plans’ public availability. These documents are legally mandated and form the cornerstone of local prevention, preparedness, response, and recovery. The research combined a systematic search for publicly accessible plans across all 265 municipalities with a detailed review of the plans from the 27 regional centers. A GIS dataset was constructed linking municipalities with plan availability, population data, and direct links to documents. The analysis revealed that while most municipalities publish disaster-related documentation, accessibility remains uneven and many documents are hidden in poorly organized websites or uploaded as scanned image-only PDFs, limiting usability. Structural analysis of regional center plans showed that all cover the legally required hazards of earthquake, flood, and nuclear or radiological accidents, but the depth, clarity, and inclusion of additional risks vary widely. Only a few municipalities integrate climate change and emerging hazards, while most remain focused on traditional risks. The findings point to a gap between formal compliance with the Disaster Protection Act and effective public-oriented disaster planning.