This paper presents preliminary results of an assessment of different urban transformation scenarios, associated to different planning choices, and highlights the impacts generated by the consequent land-use changes. In particular, the analysis evaluates the environmental impact of a change from natural land use (forest land and cropland) to urban land use for a reference area of 1 ha located in Lombardy (Milan hinterland) and two settlement scenarios (characterized by different population densities). Impacts are quantified in terms of energy consumption and CO2 emissions, related also to the reduction of the carbon stock.