The issue of affordable housing has again become crucial in ensuring a greater social equity, increasing social cohesion and reducing inequalities within metropolitan or regional systems which, in the current climate of severe economic crisis, have to respond to global challenges of development, innovation and sustainability.This study aims at building a system of knowledge about the housing affordability on the territorial scale, by which to identify the local characteristics of housing problems that could be solved through traditional planning tools or new practices of social housing, which involves private stakeholders and/or public administrations. This system of knowledge should include the analysis of the wealth distribution both in terms of income and real estate market price, and the calculation of the income-thresholds (based on the HAI-Housing Affordability Index) that filter the access to the real estate market.