Toward enhanced ecodesign of urban project thanks to City Information Modelling

Environmental impacts are to be taken into account as early as possible in the design stages of urban projects so as to be able to select the most sustainable design. Nowadays, more and more district digital models, modeled according to BIM (building information modeling) standards and guidelines, are produced during the conception and construction of new or renewed districts. City Information Model (CIM) can store data about buildings, underground utilities, roads, city furniture and vegetation (positioning, dimensions, materials and sometimes technical properties). Data about buildings are already used for Life Cycle Assessment (LCA) at the building scale (Marrero et al. 2020) and have been exploited at the district scale to evaluate impact of materials used for construction (Delval et al. 2018). A consequential approach (ie. evaluating environmental consequences of a change in the existing system, here the building stock or the city) could be considered as the most relevant for
ecodesign objectives but is too rarely performed (Frischknecht et al. 2016; Roux 2020). Complementary data from CIM could be used to enhance consequential LCA at the district scale and simulate various scenarios (local climate conditions, shadow analysis from building morphology, impact of public spaces, roads and underground utilities, etc.). This induces a greater complexity as far as data modeling and processing are concerned. Research on urban analysis from CIM data has shed light on numerous issues to be tackled in order to be able to perform analysis at the district or city scale thanks to a CIM, including georeferencing, level of detail management, definition of specific entities and property sets and need for generalized entities (Deprêtre et Jacquinod 2021).

Through this work, we aimed at identifying more precisely CIM data potential for consequential LCA at the district scale in order to propose new methods and processes and test them on case studies. A literature review is performed on eco-design and city information modeling aside with a review on existing city models. Main research potential to improve LCA of urban projects are identified and classified according to the goal and scope of the study. A first field case study is exposed and major drags and opportunities to district LCA are discussed in this specific case where an existing model has been developed without considering an eco-design objective.