Sustainability is now targeted in nearly all urban projects, but life cycle assessment (LCA) is generally seen as too complex, so that more qualitative approaches are preferred. Indeed, the importance of environmental problems regarding e.g. climate change, human health, biodiversity and resource depletion justifies a more precise decision making process. A life cycle simulation tool has been developed to model urban projects including various buildings, streets, green and other public spaces, and networks (drinking water, waste water, district heating...). This tool, developed in an object oriented approach, associates dynamic building energy simulation and LCA, complemented with modules for open spaces and networks. A set of environmental indicators is evaluated, e.g. resource depletion, energy and water consumption, global warming, waste generation, toxicity. Several alternatives can be compared, constituting an urban design aid. Continuous improvement of the tool has been performed since the 90’s, expanding the boundaries from buildings to districts assessment. A dynamic model was recently introduced to take into account temporal variation of the electricity consumption in buildings and interaction with the electricity system. Results show the importance of this dynamic evaluation in the case of plus-energy buildings. This multidisciplinary approach allows comprehensive assessment of districts, constituting a decision support in early phases of urban projects. The assessment of a project in the Greater Paris Area is presented to illustrate this integrated approach.