Guglielmo Carra, Arup's Materials Consulting Lead, Europe, is a civil engineer and materials scientist. Here he outlines how the construction industry needs to change the way it thinks about waste, and how structural engineers can contribute.
Rethinking production and the life cycle
Despite continuing efforts to reduce inefficiencies in the construction industry, excessive waste remains a problem: there is a real need to rethink production of components and systems (which are inefficient from a resource use and manufacturing technology standpoint) making better use of advanced manufacturing technologies and prefabrication.
When we think about waste we also have to consider maintenance and asset management of buildings, which are frequently inadequate, relying on limited data to monitor the building’s condition. This means that when a building reaches the end of its life, a critical stage, it’s hard to practice selective demolition - which could retain parts of a structure and reduce waste.
Some companies try to reduce waste by using demolition contracts that allow an effective stream of construction waste - however, this is typically limited to traditional construction materials, such as concrete and metals. The issue becomes more complex when you consider composite materials, and complex building components and systems. There is a need to develop regulations and procedures to allow the recovery of more demolition waste.
Disassembly not demolition
Really we should use the term ‘disassembly’ rather than ‘demolition’ - meaning that each material should be chosen and designed to be easily detached and separated from the others. Even better, a ‘selective disassembly’ would allow components still in good shape to be reused in other projects and construction works. This is not fiction, but well-established practice in other industries, such as the automotive industry. There are limited examples of established recycling in construction: steel, aluminium and copper are reused in secondary production streams, while concrete is ground and re-used as filler in future mixes. Still, there is a long way to go. The advance of technology and digital platforms will be a key enabler of a transition to selective disassembly.
Urban Bio-Loop: Sharing Waste
There is much to do to expand re-use, re-manufacturing and re-cycling in the construction sector, but I see an opportunity to merge different sectors to share waste as a resource. The example that we present in The Urban bio-loop: Organic waste from our cities and the coutryside, traditionally managed through landﬁll and incineration could become a resource for the creation of construction engineering and architecture products, before being fed back into the biological cycle at the end of their service life. Opportunities like this will become more valued in the future, as stakeholders realise waste is actually a precious resource.
An important first step is to work with governments to rethink construction codes and regulations, providing opportunity to repurpose waste on an industrial-scale.
Then we need to invest to develop bio-based materials, proving their applicability from a performance standpoint, for example, in respect to fire performance or durability. Improved understanding will allow us to exploit the huge untapped potential of organic resources in construction for specific applications.
Bio-composite materials are a mix of bio-polymers and natural fibres. Their advantage is that, depending on the case and polymer composition, they are compostable and biodegradable. These products are derived from natural resources that grow abundantly in nature, such as hemp, flex, jute and soy so are potentially infinite, regenerable, and clean.
Arup recently demonstrated that a circular building approach, using entirely re-usable components, is very possible - through the circular house project.
A number of factors need to be refined to make circular buildings more attractive from an investment standpoint, as well as to mitigate associated risks. Regulations and a governance-level approach will be needed to make this transition happen in the future, alongside a large education campaign to make stakeholders aware of the benefits of a circular economy.
3 ways structural engineers can help create a zero-waste future:
- Design for the End of Life - Engineers should work for a different design approach, that pays more attention to the end of buildings’ lives, and how structural components could be designed to be easily detachable and possibly re-usable.
- Design for future flexibility - Engineers can ask design teams to consider buildings’ future functional implementation, in case of design life extension and repurposing.
- Design for an efficient use of resources - engineers should promote the use of the latest manufacturing technologies to minimize resource consumption, without compromising the performance.