Una possibile risposta per l'adeguamento sismico e la valorizzazione dei borghi antichi: il protocollo "Casa21"

The refurbishment of existing buildings is today mainly directed to the energy efficiency and indoor comfort aspects, while the reduction of the seismic risk is left in the background, if not totally ignored. This paper presents the results of a research that has led to the development of an innovative construction system based on the use of CLT panels (Cross Laminated Timber) and an assessment pro-tocol for the reconstruction, the seismic and performance retrofitting of old Italian villages. The project, named "Casa21", considers the building as a whole, and can be applied both for the seismic retrofitting and the upgrading of the existing buildings to the new standards of construction, as well as for the construction of new buildings and for the post-earthquake reconstruction. In the first case, typical of historical and artistic high value buildings, it operates through the emptying and the reconstruction of a new building within the existing façades, that are connected to the new CLT structure with appropriate connectors. In the second case, it operates through the complete demolition and the reconstruction of the building with a CLT panels structure and an outside coating layer in line with the local building traditions. The paper illustrates the construction system characteristics, main applications, potentiality and technological details and it describes the case of a prototype building, designed following the "Casa21" protocol and recently completed in the municipality of Pienza (SI).