The environmental impact of the construction and demolition industry is enormous. Thus, architectural "waste" is an issue that needs to be taken more into consideration. Especially in the case of Greece, where the problem of the aging building stock, also, needs to be faced, the management of the existing building volume emerges as an extremely important aspect. To date, the most environmentally friendly treatment tactic, of the waste generated during the construction and demolition of buildings, is considered to be recycling. However, in recent years, new methods of approaching the existing building material, but also the design, appear in the light of the circular economy. For this reason, the practice of "upcycling", i.e. the reuse of elements of buildings, in a way that creates a product of higher quality or value than the original, is studied in this research. The design of buildings with the possibility of disconnecting and reconnecting their members, so that they can be reused in the future (Design for Dissasembly) will also be investigated. These techniques are analyzed as methodologies, as well as ways of acting against the existing problem of building volume as waste. Through the analysis of examples of different scales, the way of their application in architecture is further studied both technically, in relation to the materials that are (re-) used and their connection forms, as well as aesthetically, in relation to the spatial qualities that are created. Furthermore, the social aspect of reuse in architecture is also taken into account.