Spatiotemporally Explicit Mapping of Built Environment Stocks Reveals Two Centuries of Urban Development in a Fairytale City, Odense, Denmark.

The urban built environment stocks such as buildings and infrastructure provide essential services to urban residents, and their spatiotemporal dynamics are key to the circular and low-carbon transition of cities. However, spatiotemporally explicit characterization of urban built environment stocks remains hitherto limited, and previous studies on fine-grained mapping of built environment stocks often focus on an urban area without consideration of temporal dynamics. Here, we combined the emerging geospatial data and historical maps to quantify the spatially and temporally refined stocks of buildings and infrastructure and developed a novel indexing method to track the construction, demolition, and renovation for each building across various historical snapshots, with a case study of Odense, Denmark, from 1810 to 2018. We show that built environment stock in Odense increased from 80 t/cap in 1810 to 279 t/cap in 2018. Their dynamics appear overall in line with urban development of Odense over the past two centuries and well reflect the combined effects of industrialization, infrastructure development, socioeconomic characteristics, and policy interventions. Such spatiotemporally explicit stock mapping offers a physical and resource perspective for measuring urbanization and provides the public and government insight into urban spatial planning and related resource, waste, and climate strategies.

Spatiotemporal tracking of building materials and their related environmental impacts.

Urban development will increase the demand for new buildings expected to cause significant environmental impacts in the coming decades. Spatiotemporal prediction for new buildings, their typologies, resource quantities and types required for construction, and the associated impacts are crucial to effectively tackle strategies to reduce the related greenhouse gas emissions. Within the context of Denmark, this study establishes a prognosis of expected yearly embedded impacts across the country towards 2050 based on Business as Usual (frozen policy) trends. Through the Holt-Winters method's additive version, the study forecasted the future amount of building types in each Danish municipality. The embedded impacts disaggregated into building types, components, materials, and life cycle stages are calculated from the material intensity coefficients of real projects. Considering a 'business as usual' scenario, the prediction shows an increase in demand by 6.5 % for new gross floor areas compared to the number of current buildings constructed in the past years. The GHGs from the upstream processing of materials correspond to 7 % of current consumption-based yearly emissions in Denmark. To strive for sustainable development, the findings of the study help inform stakeholders in the built environment to better correlate the material mechanism 'supply-demand' for circularity and where efforts to minimize the impacts should be prioritized.