Design for reuse and recycling
A building consists of materials and products combined into a whole unit. The way in which this is done has a significant impact on the lifespan of the materials and components used and their potential for reuse and recycling. For example, the laying or integration of electrical cables in walls or behind finishing materials leads to a certain production of waste when they need to be replaced or removed. Or opting for spray foam insulation against a concrete structure means that the concrete cannot be recycled in the event of future demolition. If we want to limit the waste a building produces during its entire life cycle, and not just during the construction phase (see also the part on 'waste management and maintenance'), design choices must take into account both the use phase (maintenance, replacements, repairs, renovations) and the end-of-life phase (option to disassemble, reuse, recycle).
- Meaning and importance
- How was this included in the Circular Built tool?
- How can you measure this?
- CBCI Living Lab examples
- Which tools can help us here?
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.
At end of life:
When designing the building, we can already prepare for its end of life by ensuring that the construction materials and elements can be reused or recycled. To be able to bring construction materials and products back into circulation, it is essential that we can remove them from the building intact and in an economically feasible way. Designing with future recoverability in mind is called ‘design for deconstruction’.
The ability to disassemble components and connections for reuse or recycling depends on several factors:
- Accessibility: the elements and their fixings must be easily accessible;
- Connection techniques: connections without fixings or with reversible fixings are preferred. Furthermore, the number of different types of fixings should be kept to a minimum.
- Risks: the elements must be selected so that the handling risks during assembly and disassembly are as small as possible and so that simple, everyday tools can be used;
- Time: preference is given to constructions with as few components, fixings and fixing types as possible in order to limit the disassembly time. In addition, they must be designed so that disassembly can take place in different areas at the same time.
- Information: all the info to be able to correctly disassemble the elements needs to be provided. More specifically, the materials, components and their method of assembly must be documented and, if necessary, a disassembly guide must be provided.
- Standardisation of shape and dimensions: prefabricated modular components that are easy to manipulate are preferred. In addition, the number of different components in the same construction must be limited.
How can you measure this?
In the Circular Built tool, this is ‘measured’ in a simple way by verifying a number of criteria and assigning a score to each one. However, there are other ways to measure the extent to which building components have been designed for reuse and recycling, and some of them are very precise.
- The most detailed way is to use the Reuse Potential Tool developed by Elma Durmisevic. This provides you with a very detailed score to express the reuse potential for an entire building. The theory behind the method is described in Elma Durmisevic’s report ‘Reversible Building Design’. Currently, this method still involves a very intensive calculation phase, but in the future this could be automated based on BIM information. Reversible Building Design – Elma Durmisevic – BAMB 2018
- Durmisevic’s theory was also used as the basis of the measurement methodology for the detachability index, albeit in a basic, simplified way. This methodology allows you to express – using a detachability score – to what extent a construction node has been designed for reuse and recycling. This method was integrated into the Breeam.nl Report on a Measurement Methodology for the Detachability Index v2.0 (Dutch) – Alba Concepts, DGBC (Dutch Green Building Council) Detachability Index Tool (Dutch) – Alba Concepts, DGBC
- In Level(s) there is a calculator ‘Design for Deconstruction’ for level 3. This is also a simplified version of Elma Durmisevic’s method. Level(s) indicator 2.4: Design for deconstruction
- In the building certification scheme of the DGNB (the German abbreviation for the German Sustainable Building Council), there is an indicator (TEC1.6) that assesses the extent to which the different functional layers of the building have been designed for recovery and recycling. TEC1.6 Ease of recovery and recycling
Which tools can help us here?
- Calculator “design for reuse and recycling” which is part of the Circular Built tool (go to my projects)
- The End of life calculator was developed within the CBCI project, in cocreation with clients and parties in the construction sector. This tool helps to estimate the economic added value of remountable construction early in a project. For example, it allows clients to concretise the value of "facilitating end-of-life disassembly". With this information, clients can sharpen their plan and factor the value into design and investment decisions. Video on how to complete the tool?
- Video with lessons-learned from the Temporary Court Asterdam (Dutch) which was built completely demountable and has since been dismantled and reassembled in Enschede