Pre-existence and prefabrication. Lacaton & Vassal: methodologies for social housing renovation

«Our approach is to give more to do better. In France, between 2006 and 2015, 125,000 dwellings were demolished and 100,000 rebuilt. The cost of demolition and reconstruction of one dwelling amounted to 165,000 euros. Our alternative approach showed that it is possible to significantly transform a dwelling for the cost of 55,000 euros. Transformation means openness, extension, more space, more light, more freedom of use» (Lacaton, 2020). This article discusses the methodologies developed by Lacaton & Vassal for social housing in French suburbs and examines their “alternative approach” from a constructional and bioclimatic standpoint. Two emblematic cases are taken as an example: the transformation of the Bois-le-Prêtre in Paris and the renovation of three residential blocks in the Grand Parc of Bordeaux