Life cycle assessment applied to urban settlements and urban morphology studies

Thèmes : ville durable, analyse cycle de vie, environnement, quartier, thermal simulation, life cycle assessment, outils aide décision, impacts environnement, urban morphology
Life Cycle Assessment (LCA) is increasingly used to improve the environmental performance of products, and its application in the building sector seems promising. Several tools have been developed and compared in the frame of the European Thematic Network PRESCO (Practical recommendations for sustainable construction). An LCA model has been developed for Settlements, in order to help the decision making process during their design or renovation. The system considered includes buildings, public spaces (streets, parks...) and networks (drinking water, sewage, district heating). All phases of the life cycle are modelled: fabrication of products, transport, construction, operation, renovation, dismantling and waste treatment with possible recycling. This model allows an evaluation of different impact indicators (e.g. resource depletion, energy and water consumption, global warming, waste generation, toxicity...), and the comparison between different design alternatives to be performed. The aim is to assess the influence of buildings and urban morphology on the environmental impacts of a settlement project. The operation phase is long lasting, so that processes like heating/cooling play an important role in the global environmental balance. Decisions made at the level of the settlement (orientation of streets, compactness and urban density) have a large impact on heating/cooling loads. Therefore the LCA tool is linked to thermal simulation. Some development is on-going regarding dynamic‐LCA aspects, particularly accounting for the temporal evolution of the electricity production mix. This communication presents an application of the model on case studies inspired by Quartier Vauban in Freiburg. The aim is to define a best practice reference to which other projects can be compared.