Eco-friendly exoskeletons for enhancing resilience of the built environment.

Recent natural disasters in the form of earthquakes and extremes events associated to climate-change have further confirmed the need for an urgent effort to improve the resilience of the built environment. In parallel, resource-efficient structural design is growing in interest, and major effort has been focusing to the implementation of nearly-zero energy buildings or net zero carbon construction by using low-emission and eco-friendly materials. Despite this ambitious goal for designing new buildings, the renovation of existing ones in a low-carbon manner remains challenging. This is the case when the upgrading must address both energy performance and other resilience requirements, for example buildings featured by high seismic vulnerability and poor energy performance, that pre-date modern codes that regulate seismic design and energy performance. Even though several solutions have been proposed for the integrated renovation of existing buildings, this study identifies the advantages of, and proposed a framework for, a holistic approach based on a novel technology implementing timber-based, low-damage external exoskeletons. The seismic-resistant low-damage technology considered is the Prestressed-Laminated (Pres-Lam) timber technology, proposed at the University of Canterbury, and implemented in several buildings around the world. The exoskeleton allows for the seismic strengthening/retrofitting of the existing building, and provides the support for a “double-skin” system, also allowing for the improvement of the energy efficiency and for architectural renovation, ensuring an holistic and integrated rehabilitation of buildings. All the components used (i.e., structural/non-structural) are based on dry connections, thereby enabling demountablity/reusability at end of life. This study demonstrates the potential of this technology by means of structural/ energy numerical simulations on a case study building. Furthermore, it points out the importance of a careful and efficient use of the resources in terms of materials used, for implementing an integrated approach that ultimately improves the resilience, efficiency, and sustainability of the built environment.