Part 2: Circularity in Infrastructure |
IS Thought Leadership By Dr. Jim Goddin, Technical Director Circular Economy
Applying the rationale behind the Material Circularity Indicator (MCI) to infrastructure projects, where are we today and how might MCI inform where we go next?
MCI has already started to see adoption within the industry. InfraBuild recently published their MCI scores alongside their EPDs (the first company in Australasia to do so). This is an encouraging development as there is often an assumption that becoming more circular is enough to improve environmental impacts. This isn't always the case, and the system has to be considered as a whole. Components of implementing a circular economy, such as reverse logistics and additional handling or storage, can significantly change the economic and environmental calculations. Placing EPD and MCI results together is an effective way of demonstrating that the system is being considered holistically and optimised effectively.
Elsewhere MCI and EPD results are starting to form part of the selection criteria for the interior fitout of buildings and some sectors are starting to use MCI, both as a component of their internal design toolkit and for feeding into their science-based targets.
Many of the circular economy initiatives we see in the construction and infrastructure sectors are, however, still stuck in the incremental mindset of doing 'less bad' while minimising disruption to business as usual, typically focussing on waste reduction activities. While reducing waste is undoubtedly a step along the road to a circular economy, on-site waste reduction practices should really be standard practice across the board at this stage. Only shipping to site the materials you need and ensuring that large quantities of these materials don't end up going straight into a skip, simply makes good business sense and goes some way towards reducing the negative impacts and costs of construction.
The adoption of industrial symbiosis, utilising surplus resources from your own or another's activities, is an excellent way to reduce the virgin content coming into your product and minimise waste elsewhere. Here though, we do have to keep in mind the whole lifecycle of the product and look very carefully at what the use of recovered material may mean for future recovery options. When looking at plastics, for example, it is straightforward to create inexpensive and reasonably durable products from mixed plastic streams that would otherwise have little market value and end up in a landfill. The options to recycle these materials (sometimes referred to as monstrous hybrids) can be almost non-existent due to the diverse nature of the polymers, meaning that the production of waste has simply been kicked down the road rather than avoided altogether. Such products will still become waste and, with plastics, in particular, this is something we need to avoid.
We also need to keep in mind that our use of recycled material may be of lower value than alternative solutions. In the example of the mixed plastic above, greater circularity (and economic gain) might be achieved by instead designing products to use a single grade of plastic or to add separation infrastructure to avoid mixing in the first place – leading to a higher value material that can be maintained in use for longer. Or better yet, establishing systems on top of this to ensure the plastics can be reused many times before needing to be recycled at all.
In construction and infrastructure, it's tempting to think of concrete as an ideal option for materials we don't know what to do with. Indeed, as a means of sequestering problematic materials, the volumes are there, and a proportion of recycled content would improve the circularity. For example, if we used 20% recycled aggregate in a concrete bridge, we would get an MCI score of around 0.2 (on a scale of 0 = Linear, 1 = Circular) without any form of end of life strategy in place. But we still need to ask ourselves what the nature of that recycled content means for the durability of that bridge and whether we might be creating another type of monstrous hybrid.
If we were to instead design the same bridge to remain in service for twice as long, we would effectively halve the materials requirement overall. This doubling of the service life gives us an MCI score of almost 0.6 without any recycled content. Looking at this another way, to match the circularity of introducing 20% recycled content on a 40-year design life structure, we would only need to extend the lifetime by 4.5 years. Of course, if we can use recycled content and extend the design life, then that is better still.
Image: Comparison of the Material Circularity Indicator (MCI) for three basic circular economy options for a 40-year design life structure
Might it be a more effective circular option to invest in better materials and/or in perfecting higher quality builds to extend the design life? A problem with this approach is that long-lifetime products, such as those found in aerospace or in infrastructure tend to be very expensive up-front and also tend to become outdated within their own lifetime, lasting long enough to be inadequate or insufficient before the end of their natural service life.
Image: The Auckland harbour bridge, built in 1958 and extended in 1969 to cope with significantly greater traffic, can be considered both as an example of the adaptation of infrastructure to changing needs, as well as an example of failing to predict future needs. (Photo credit Phil Botha, UnSplash)
For infrastructure projects, what we need today isn't the same as what we'll need in the future, and we usually don't know what we may need. For example, we've typically needed more roads as society has developed. With autonomous vehicles and the threat of pandemics impacting commuting, this trend might go into reverse perhaps and radically change our needs.
The challenge, in either case, is one of adaptability. Given that a building/road/bridge/car park may last 40+ years, how do we ensure that we don't need to knock it down before this because our needs have changed? How can we ensure that future needs can be accommodated by extending the existing infrastructure? How do we also ensure those structural components last beyond the initial structure and design them so for reuse in whatever comes next? And how do we address that most challenging cause of premature demolition – people falling out of love with the architecture of the past?
If we can address these then, perhaps, we can get circularity right for the infrastructure sector.
About the Author:
Dr. Jim Goddin is the Technical Director of Circular Economy at thinkstep-anz. He specialises in circular economy systems design and worked alongside the Ellen MacArthur Foundation to co-author the widely adopted Material Circularity Indicator methodology. He is a Chartered Engineer with a PhD in materials engineering and is both a Fellow and a Strategic Advisor of the Institute of Materials, Minerals and Mining. Jim has worked extensively on the development of eco-design tools and the assessment of business risks resulting from critical materials and hazardous substances legislation.