Integrated Deep Renovation of Existing Buildings with Prefabricated Shell Exoskeleton

Abstract

The European goal to reach carbon neutrality in 2050 has further put the focus on the construction sector, which is responsible for great impacts on the environment, and new sustainable solutions to renovate the existing building stock are currently under development. In this paper, the AdESA (Adeguamento Energetico Sismico ed Architettonico, in Italian) system, a holistic retrofit technique for the integrated renovation of the existing buildings, is presented. The system was developed by a consortium of enterprises and universities and was applied to a pilot building. The system consists of a dry, modular and flexible shell exoskeleton technique that implements different layers depending on the building retrofit needs (cross-laminated timber (CLT) panels for the structural retrofit, thermal insulation panels for the energy efficiency amelioration, and claddings for the architectural restyling). In order to foster actual sustainability, the solution contextually targets eco-efficiency, safety and resilience. To this end, the system not only couples the structural and energy interventions to reduce the operating costs, but it is also conceived in compliance with life cycle thinking (LCT) principles to reduce impacts throughout the remaining building service life (from retrofit time to the end of its life). The system is designed to be easily mountable and demountable to allow for the reuse/recycling of its components at the end of life by adopting macro-prefabricated dry components and standardized connections, to reduce damage caused by earthquakes by reducing the allowed inter-story drift, and by amassing the possible damage into sacrificial replaceable elements. The paper describes the AdESA system from a multidisciplinary perspective and its effective application for the deep renovation of an existing gymnasium hall.

In-plane capacity of existing post-WWII beam-and-clay block floor systems

“…This leads to a reduced stress level in the new structural elements and in the foundation system and to a higher lateral stiffness compared to the shear wall solution. Some examples of shell exoskeletons are wooden shells (Zanni et al 2020(Zanni et al 2021, steel shells, or steel diagonal grid systems (diagrid exoskeletons) (Mele et al 2021;Di Lorenzo et al 2020;Labò et al 2020), which may be in adherence of the existing building or may present an offset with respect of the building façades.…”

Technological analysis of a prefabricated timber-based system for the integrated renovation of RC framed buildings

“…First works on this topic have been carried out by Sustersic and Duijc [17], who proposed a low invasive retrofit solution consisting in applying a new outer CLT-shell to the external envelope of the building by realising the connection between the panels and the RC structure through special steel brackets provided of ductility and energy dissipation capacity. The external application of CLT panels has also been investigated within the AdESA project [18], resulting in a real application in a case study. The Adhesa system uses dissipative connections with out-of-plane bending capacity and provides for cladding the CLT panels on-site with insulation and finishing materials.…”

The LCT Challenge: Defining New Design Objectives to Increase the Sustainability of Building Retrofit Interventions

“…Finally, when natural hazards are considered, construction systems may be designed for minimizing possible damage, adopting stricter structural design targets, and/or for lumping the damage into sacrificial structural fuses, which allow for ductile collapse mechanisms and which may be easily replaced after the hazardous event [20,[44][45][46]. In the former case, this principle may be in contrast with the principle of material optimization, since higher dimensions of the structural elements could be required.…”

“…Finally, some strategies may be adopted to increase both the sustainability and the feasibility of the retrofit interventions, thus overcoming some of the major barriers to the renovation. Applying a retrofit solution from the outside of the building would avoid occupants' relocation, but also reduce demolition of internal finishes, thus reducing the raw material and waste streams [20,[44][45][46]51]. Incremental rehabilitation, instead, is a strategy that allows one to distribute retrofit actions in time, combining them with programmed maintenance interventions, as long as each step increases the performances of the building with respect to the previous one.…”

“…All these LCT principles, when adopted at an early stage of the design, allow for the selection and design or reengineering of sustainable construction techniques, especially when coupled together. An example of a combination of these principles is presented in Zanni et al (2021) [46], where a holistic (seismic, energy and architectural) retrofit intervention from the outside, inspired by LCT principles, was designed and applied to a real case study.…”