# Integrated Deep Renovation of Existing Buildings with Prefabricated Shell Exoskeleton
## 2 AdESA System: An Anti-Seismic, Eco-Efficient Wooden Shell  
AdESA is a new system for the structural, energy, and architectural retrofit of the existing building stock of the urban outskirts [16]. The AdESA system entails the use of innovative technologies and virtual design systems (BIM), and it is based on the application of a layered shell to the existing building, encompassing: (1) a structural layer, consisting of an anti-seismic shell made of prefabricated cross-laminated timber (CLT) panels (or similar) and a fire protection layer, if necessary; (2) an energy layer, consisting of a thermal insulating coating; and (3) an architectural layer, encasing the previous layers with highly customizable finishes, ranging from simple skimming, to maintain the appearance of traditional plaster, up to coatings with high architectural and technological impact (Figure 2). As for the structural and energy layers, they are applied only if needed. When the existing building is already provided with thermal insulation panels, the structural, architectural, and possible additional energy layers may be applied without removing the existing panels, except for those areas corresponding to the floor and the roof, where connections between the building and the shell are introduced. On the other hand, when a portion of the building does not need structural strengthening or requires minor interventions, the energy and architectural layers only may be implemented. As for the architectural layout, depending on the urban constraints, the system allows for different levels of morphological transformation, determined by the choice of the shape of the shell and the offset from the existing building facades. The shell may be either in close proximity to the building, thereby creating a structural-energy coat, or placed at a distance to obtain volumetric expansion with the introduction of new living spaces. The AdESA system was conceived to maximize the synergies of an integrated intervention, by reinvesting the tangible and immediate gain achieved with energy efficiency amelioration to partly compensate for the costs of the seismic improvement, thereby increasing the feasibility of the retrofit. In addition, the system was conceived as highly industrialized both in terms of the production process and for the installation of components, ensuring construction times, site management and costs comparable to those of energy and architectural interventions, but with additional benefits in terms of the safety of the building and of the inhabitants. From an LCT point of view, the system is conceived to reduce environmental, economic, and social impacts throughout the whole building life cycle, and beyond, thus also implementing the concepts of the circular economy. In the production stage, the system adopts eco-efficient materials, either new and certified raw materials from renewable sources, with Environmental Product Declarations (EPD), or recycled/reused elements. Each component of the engineered shell is highly industrialized. Construction materials are optimized by providing multiple functions to the same element (e.g., reducing the thickness of the energy layer by exploiting the thermal properties of the structural panels, optimizing the traditional connection systems, etc.). In the construction process stage, impacts are reduced through the adoption of dry technologies and the prefabrication of components. Components are pre-cut using computer-controlled cutting machines implementing BIM-based algorithms, transported to the construction site, and are easily moved by light cranes. Depending on the adopted technologies, structural, energy, and architectural layers may either be set up in sequence, at the construction site or previously assembled off-site and shipped as a unique modulus. Connections are also prefabricated in the factory and standardized to minimize installation operations, as well as to enable removal and reuse at the end of life; connection detailing is designed to enable managing the inevitable construction tolerances.