Quantifying and mapping embodied environmental requirements of urban building stocks

Cities and their building stocks result in huge environmental impacts which are critical to reduce. However, the majority of existing studies focus on operational requirements or on material stocks. To date, very few studies have quantified embodied environmental requirements of building stocks and spatialised them. This study describes a bottom-up approach to spatially model building stocks and quantify their embodied environmental requirements. It uses a highly disaggregated approach where each building's geometry is modelled and used to derive a bill of quantities. Construction assemblies relevant to each building archetype (derived based on land-use, age and height) are defined using expert knowledge in construction. The initial and recurrent embodied energy, water and greenhouse gas emissions associated with each material within each assembly are calculated using a comprehensive hybrid analysis technique. This model is applied to all buildings of the City of Melbourne, Australia. Results show that rebuilding the City of Melbourne's building stock today would require 904 kt of materials/km2 (total: 32 725 kt), 10 PJ/km2 (total: 362 PJ), 17.7 Million m3 of embodied water/km2 (total: 640.74 Million m3) and would emit 605 ktCO2e/km2 (total: 23 530 ktCO2e). This study demonstrates the breadth of the model outputs, including material stocks maps and breakdowns of life cycle embodied requirements by material, construction assembly, building and building typology at the city level. Using such model, city councils can better manage building stocks in terms of waste processing, urban mining and circular economy, as well as reducing embodied environmental requirements over time.

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