## 5 Results
The use of reversible assembly techniques (such as bolting for the connections of structural nodes of structural steel or timber profiles or the interlocking of a reinforced concrete pillar in a prefabricated plinth) and modular components that allow the reciprocal interlocking and the structural collaboration (such as the reinforced concrete panels of facades and floors) allow the construction of the building to be completed more quickly, due to the absence of binders, and with the help of a reduced number of laborers and machinery [69]. The structural elements are often designed to host non-structural elements, such as floors and internal partitions, which can also be integrated with finishing elements (plastic, cladding, flooring) or thermal and acoustic insulation, as well as facade walls that already have the housing for doors and windows [72]. It is evident that buildings made of prefabricated components generally present a high degree of deconstruction ability, since, at the end of their lifecycle, they often do not need to be demolished but rather need to be processed with a \"construction-on-reverse\" strategy that goes step by step, starting from the non-structural elements up to the structural ones. The relative ease and speed of disassembly allows many \"second-life\" options regarding reuse and recycling: doors and windows can be disassembled at low risk of damage and sold in the second-hand market [87]; the ceiling and facade panels can be dismantled and stored until a possible subsequent reuse in another lifecycle [88]; the steel and wood structural elements can be reused several times, down-cycled, and then recycled [86]. It must be said that these results can only be obtained due to an accurate study in the design phase and the level of detail of the techniques with which the connections are obtained [66]. Finally, on the basis of the considerations made so far, it is possible to define a series of principles that can allow an easier and more efficient deconstruction of a building for the reuse and recycling of deconstructed components, regardless of the construction system and the materials used. These principles, which must necessarily be considered in the design phase to be effectively valid, can be summarized in major groups, depending on the strategy level:  
1. Reduction of the building complexity. A good strategy to reduce complexity is to minimize the number of components, for example choosing fewer but larger elements. The use of modular and lightweight building components, manufactured in a factory and then assembled with codified procedures also contributes, improving buildability as well as simplifying the deconstruction process, as well as the storage and transportation in large units. In addition, it is possible to act on the connections between the elements: simplify the connections, making them visible or accessible, can allow efficient construction and deconstruction, reducing the need for a high range of tools as well as reducing the installation time. The simplification of the connections between non-structural elements allows separating the openings and the technical systems within non-structural elements for the further selective removal of the components. 2. Smart choice of materials and building components. The utilization of materials that are worth being reused and/or which are eco-compatible allow for adaptability and repurposing in the future in a new lifecycle. Materials such as wood, steel members, brick, and carpet tiles can easily be reused or refurbished, unlike materials such as cement, concrete, mortar, and plaster, which are often intended for landfill. Hazardous materials should be avoided, but if they are required for any reasons, it should be considered to tag them for a fast identification, so they can be properly handled at the end of their life.