26. Urban Agriculture for Urban Regeneration in the Sustainable City

Dense cities are often perceived as universal models for urban transition to sustainability (Williams et al. 2000). Of course, there is a strong case for considering high urban density as a requisite for sustainability, if only because sustainability usually means making a better use of what is already there—for example, recycling the urban fabric and urban functions without going through phases of degraded neighbourhoods (Whitehead 2003). This is all well and good, but it should be accepted nevertheless that low urban density offers some advantages as far as sustainability is concerned. It reduces the concentration of nuisances and pollution and lowers the density of urban centres that are sometimes on the brink of congestion (Neuman 2015). Besides, climate policies introduce new arguments for low-density urbanizations. Green neighbourhoods planted with trees presenting a high water loss coefficient can lower the local temperature (Boutefeu 2007). In low-density areas, more square metres of roof per household are available than in high-density areas; thus, generalized photovoltaic roofs can be significant. Such facts compel us to cast an eye without prejudice on the very notion of sustainable city, which does not consider from the start that “sustainable” means “dense”.