The EPICEA project is a joint collaboration between the City of Paris, the French Meteorological Office and the National Research Centre in Building to quantify the impact of climate change on Paris and the influence of building on urban climate and on adaptation strategy. First goal is to evaluate the evolution of the urban climate of Paris and its area with regard to climate change. Second goal is to realise a sharp analysis of the 2003 heatwave over Paris with simulations using a database of the Parisian urban cover. The ultimate goal is to assess the climatic impacts during heatwave periods that could result of actions on urban parameters. This information will allow the mapping of heatwave vulnerability.