Improving the integration of outdoor spaces in urban project ecodesign tools 

Cities are, by definition, centers of accumulation: of population, buildings, goods, and resource consumption (energy, raw materials). These concentrations generate multiple social, technical, and environmental consequences. To address these challenges, ecodesign—aimed at reducing the environmental impacts of a product or system throughout its entire life cycle—is increasingly recommended. Within ecodesign, Life Cycle Assessment (LCA) is generally chosen because it is considered the most comprehensive, rigorous, and suitable method for assessing impacts at the urban project scale. However, in urban planning, LCA has historically focused on buildings and has addressed outdoor spaces only in a simplified manner. Yet these spaces play a crucial role in meeting expectations related to reducing urban heat islands, limiting stormwater runoff, or contributing to carbon storage. This dissertation seeks to enhance existing tools by developing more detailed models dedicated to evaluating these components of urban districts. 

A first model was developed to assess the environmental impact of pavements, from construction through maintenance. It introduces processes that are usually absent from environmental databases, enabling more complete evaluations. When applied to a real district, the model shows that pavements account for less than 3% of total impacts, although reducing their footprint remains important in a context where public-space interventions are becoming more frequent and must adapt to future climate conditions. 

The research then focuses on green spaces, particularly urban trees—the main providers of ecosystem services in cities, such as stormwater reduction, carbon storage, and improvements to quality of life. A model that integrates tree growth makes it possible to better quantify these services and highlights the importance of mature trees, whose canopy can be up to fourteen times larger than that of young trees. Applied to the case study, the model shows that trees have low environmental impacts but deliver substantial benefits, including intercepting around 20% of annual rainfall. 

Finally, an open-data compilation effort led to the creation of a database containing more than 300,000 urban trees in France. This dataset was used to develop allometric equations tailored to the French context, enabling better estimation of tree growth and characteristics. Together, this database and the developed models open the way toward more complete tools to support urban policies, particularly regarding material choices, green-space planning, and microclimate management. 

Key words: Urban projects, LCA, Ecodesign, Pavement, Urban trees, Geodata