Digital tools-based process as circular and sustainable strategy for the renovation of existing buildings

The serious emergency conditions to which the ecosystem has been subjected in recent decades and the disastrous consequences resulting from them - including, moreover, the acceleration of the spread of Covid19 - probably related to high PM10 pollution - require the introduction of new control parameters to regulate any anthropic process. In the building sector, as well as in any production sector, the actions undertaken to face the collapse of the environmental system are aimed at limiting energy consumption, reducing CO2 emissions, promoting the use of sustainable, recycled and recyclable materials and products, according to the criteria of circularity and environmental sustainability. In this context, renovation of existing recent buildings (1950-80) constitutes a key factor for sustainability, contributing to reduce the consumption of resources and raw materials, which often have reached only half of their life cycle, as well as to extend the buildings' long-term functionality. Although in many cases the cost-benefit analysis shows that the most cost-effective solution in economic terms corresponds to the demolition and reconstruction of existing buildings, it is clear that this choice cannot represent the strategy to be adopted indiscriminately. Demolition and reconstruction require the presence of temporary buildings for accommodating the same number of people hosted therein for an extended period of time, during the course of the intervention, involving the immediate expense of considerable amounts of money and a complicated management of the process by the owner or the relevant local authority. The research presents a new integrated approach to support designers and operators during the whole building process - analysis, design, realization - for the management of the refurbishment interventions, through the use of innovative continuous envelope solutions that could guarantee high performance and good quality of final products. The objective is to contribute to the development of tools for the renovation of recent buildings, proposing valid processes and methods for the design of interventions, according to the criteria of sustainability and circularity. In particular, the project is focused on the analysis of the recent building stock realized with the modern techniques of prefabrication in reinforced concrete. Today, these buildings present significant performance deficits - structural and energetic - which, for the most part, are embedded in the nature of prefabricated systems, derived from a factory production process, on-site transport and dry assembly through mechanical connections. The research seeks to investigate a new strategy for the energetic and architectural refurbishment of this building stock towards nZEBs, by proposing new envelope solutions based on a process by-products concept and an integrated circular approach. The strategy proposed is based on the implementation of digital tools during the whole process, i.e. from the geometrical survey phase with laser scanners and drones to the design phase with parametric BIM software for the customization of the solutions, and, lastly to the industrialized production phase of the envelope components with 3D printers and CNC machines.