Conservation of historical buildings and building deconstruction: maximizing preservation and minimizing materials flow

Conservation practices had been discussed since the past. To define the authenticity" aspects of a historical building as a meaning of its heritage significance, faces the problems of redundancy, deterioration and obsolescence processes are the causes for the degradation and, at the end, for the demolition of a building. However, preserving the heritage significance of historical buildings means also to maximize the preservation of their tangible and intangible heritage dimensions as a whole. To maximize the preservation of a building is also to maximize the reuse of materials, to minimize waste flow and resources consumption, and to extend the lifetime of a building as a whole. The application of building deconstruction practices to historical buildings is addressed here, by discussing its contribution to preserve both tangible and intangible heritage, and the environmental aspects related, such as the reduction of the construction and demolition waste and the consumption of non-renewable resources. Therefore, conservation of a historical building located at the historical centre of Porto, Portugal, is here presented and analyzed as a case study. The flows of materials mass and embodied energy related to the rehabilitation process were accounted, analyzed, and compared, as a way to measure the environmental benefits of materials reuse, and the preservation of their historical value. The overall results showed that in general selected dismantling highly contributes to minimize the waste flow, as well to reduce the loss of the embodied energy, especially when compared with scenarios of only facade retention.