The energy efficiency improvements in social housing have become a priority goal for the European Union, also to promote a culture of energy efficiency among the local population. Characterizing the social housing stock is the first step to be taken, followed by the thermal behaviour analysis of these existing buildings. In hot and dry climate regions such as Madrid, buildings normally use air-conditioning in order to provide an acceptable level of thermal comfort during the summer period. Many times these buildings are overcooled or the use of the HVAC is redundant and kept running for a much longer time than needed. This convectional energy consumption could easily be reduced including bioclimatic techniques. This paper presents the results of a case study example designed to monitor, analyze and evaluate the improvement indoor conditions by upgrading the thermal-physical characteristics of the building envelope in a social housing. With this aim two measurement campaigns were carried out during the summer period (2002 and 2006). The quality of thermal indoor conditions has been assessed accurately during the buildings' occupancy period. The refurbishment of the building envelope, as demonstrated, is always convenient, by considering all possible point of views, better indoor microclimate and thus energy savings [1]. (C) 2014 Elsevier B.V. All rights reserved.