Detailed energy assessment of modern prefabricated housing units with on-site investigations

Many buildings have been built in Europe in the period 1960-1980 with prefabricated systems. Today these buildings offer poor thermal performances and require serious energy retrofitting interventions. Most of them are social housing buildings. Due to the shortage of financial resources, many of these constructions are in precarious conditions and little attention is payed to their energy assessment. On top of that, there is no detailed information available on the employed building technology: the original projects are lost or, in the best cases, they are forgotten in archives. In these last years the need to improve the energy performance of buildings has emerged. Unfortunately, people approaching the energy rehabilitation of existing buildings often make mistakes in energy calculations. The aim of the paper is to give some examples of the information needed for this typology of buildings in order to facilitate their energy assessment. In the first part technical aspects of European prefabrication techniques are given, explaining some features of the buildings. In the second part a detailed investigation on a selected case study in Italy is given. In particular, some simulations of thermal bridges and joints are offered, focusing on issues related to construction details and materials. Finally, an investigation with thermal flux sensors has been carried out, in order to offer detailed information on the properties of prefabricated panels, matching the available information. The correct knowledge of details has a relevant impact on energy calculations, if the goal is to effectively improve the energy performance in soft or deep renovation projects.