The objective of this work is to propose a procedure to define the level of environmental quality of portions of urban areas. The steps of this procedure can synthetically be summarised as follows: 1) in depth study of the cultural and regulatory aspects of the sustainable development concepts; 2) setting up of a three-dimensional matrix that is able to synthesise the urban reality; 3) definition of a system of indicators of urban quality; 4) definition of a mathematical model that is able to deal with the acquired knowledge; 5) application of a study case. The study of these themes is based on the necessity of a reconciliation between the environment, growth and development over the following decades for the entire planet.