The aim of this paper is twofold: to investigate the applicability of a building-stock modelling methodology to assess the potential of Energy Conservation Measures (ECMs) and their associated effects on carbon dioxide (CO2) emissions for a building stock in a South European climate, with Spain being used as an example; and to analyse the technical potentials and costs of the ECMs when applied both individually and as packages of multiple ECMs for the entire Spanish building stock, including residential and non-residential buildings. The modelling methodology, which has been designed to be applicable to any European country, is fully dynamic and based on an aggregated description of the building stock. This paper updates and validates the methodology to account for the climate and technical characteristics of the region under study. Applying all ECMs as a package gives a potential technical reduction in final energy demand of 55% and a 65% reduction in CO2 emissions, while the corresponding techno-economical potentials are 33% and 37%. Nevertheless, the market potentials estimated are substantially lower (5-10%), which indicate that policy shifts are needed if the techno-economic potentials identified in this work are to be realized. (C) 2014 Elsevier B.V. All rights reserved.