As tomorrow’s cities are already largely built, many strategies stress the importance of urban renewalprocesses to address current energy issues. This paper focuses on the Spanish residential building stockbuilt until 2001, which has a low level of energy performance.Considering the current economic crisis, the future lies in renovating the built environment, whichholds a significant energy-saving potential. This potential is here quantified by applying the cost-optimalmethodology, initially proposed by the Energy Performance of Buildings Directive, and which calculatescost-optimal levels of minimum energy performance requirements at the building and component scale.The originality of our study lies in the application of this methodology at the territorial scale, comparingdifferent retrofitting scenarios by scaling-up building-scale results through an archetypal approach. Wealso describe an Excel-based tool allowing two types of studies: (i) at the building scale, for one archetypein a particular climatic zone; (ii) at the territorial scale, to have an overview of all building archetypesand climatic zones simultaneously. Results include economic aspects, energy consumption and savingsand associated emissions.The outcome can help construction-sector firms adapt their business plan, while also providing stake-holders with decision-support to promote a sustainable renewal of the building stock.