Meaning and importance
During the use phase:
If we want to limit waste production during the use phase of the building, when designing the building it is essential to keep elements with a longer expected lifespan (e.g. structural elements) as separate as possible from elements with a shorter expected lifespan (e.g. dividing elements). A building consists of several functional layers, which in turn consist of elements with different technical, functional and economic lifespans. We call these ‘shearing layers’. We go through them below in order of lifespan, starting with the shortest:
- Furniture: the furniture, furnishings and appliances are the objects with the shortest lifespan within the building;
- Space plan: the dividing elements and the flexible coverings (floor, ceiling and other finishes) also have a fairly short lifespan;
- Services: this layer includes all components (production, distribution, delivery, storage) for ventilation, heating, electricity and plumbing;
- Skin: this layer is made up of facade elements and exterior surfaces. One way to be able to adapt the building in the event of a change to layout or function is with a facade that is independent of the structure.
- Structure: this is the load-bearing layer of the building. It includes the load-bearing structural elements and the foundations. The structure is the layer that potentially has the longest lifespan. It is also the layer with the fewest opportunities for change and traditionally contains the largest mass of material.
- Site: this corresponds to the geographical location of the structure (eternal).
The technical lifespan of these functional layers can vary greatly, ranging from a few months to a decade. It is therefore essential when designing the building to keep elements with a reasonably long expected lifespan well separated from elements with a shorter expected lifespan. So make the shorter-lifespan components easily accessible for maintenance and/or possible replacement, in order to not damage the other functional layers during these changes to the building, and to limit waste production.
In addition, it is important to make it both technically and practically more feasible to disassemble the elements with a short lifespan. This feasibility is influenced by the hierarchy and relationships between the parts, the technical lifespan, the use of basic elements and the number of actions required for disassembly.