Integrated and sustainable renovation of RC framed buildings through a new timber-based envelope technology

In seismic European countries most of the residential building stock is highly energy-intensive and low earthquake-resistant because it was built before the enforcement of the most recent energy and seismic codes. Furthermore, it is often characterized by a low architectural quality due to poor maintenance and/or construction and design deficiencies. These buildings need deep renovation, but the use of common energy and seismic upgrading techniques is often unsustainable in terms of costs, work duration and occupants’ disturbance. Therefore, new integrated, affordable, fast and low-disruptive renovation actions are strongly needed. This study proposes an innovative energy, seismic and architectural renovation solution for Reinforced Concrete (RC) framed buildings, which consists in adding Cross Laminated Timber (CLT) panels in combination with wooden-framed panels to the outer walls; the two panels integrate insulation and cladding materials in order to improve the energy performance and the architectural image of the renovated building. Moreover, the CLT panels are connected to the existing RC frame through innovative energy dissipative devices. In case of earthquake, these devices in combination with the CLT panels reduce the drift demand of the building, preventing or reducing structural damages and consequent repair costs. In particular, this paper investigates the technical feasibility and energy efficiency of the proposed retrofitting system. To this purpose, dynamic thermal simulations have been conducted on a multi-storey building located in Catania, Italy. The results indicate that this retrofitting technique considerably improves the energy performance of the considered building, with a reduction of the global energy demand by nearly 60%. The presented study is part of a larger research project aimed at investigating also the seismic performance of the above-mentioned renovation solution.