A circular construction sector: Mirage or reality?

Baltic Rim Economies

André Stephan
Associate Professor in Environmental Performance and Parametric Design
Université Catholique de Louvain
Louvain-la-Neuve, Belgium

Andre.Stephan@uclouvain.be

Construction: a resource-intensive activity

The construction sector is responsible for most of raw material extraction, by mass. Raw materials are processed, manufactured into building products, transported to construction sites and assembled, to be locked into built stocks for decades, sometimes centuries. The processing of raw materials, their manufacturing, transport, construction, replacement and end-of-life, require significant amounts of energy and water, and result in a range of outflows, notably waste and greenhouse gas emissions. These embodied flows are very significant and can represent most environmental flows across the life cycle of a building, as research conducted by others and myself has shown.

In short, there is a critical need to rethink the entire life cycle of buildings and infrastructure, across design, use, maintenance, and decommissioning. This helps reduce resource use and environmental damage associated with construction. The circular economy (CE) is one approach in this direction and has been gaining traction.

Circularity: new paradigm or back to the roots?

The CE has three main principles: 1) eliminating waste and pollution, 2) circulating products and materials, and 3) regenerating nature. When applied to construction, most CE initiatives tend to focus either on principle one or two. An example is the use of prefabricated bio-based construction assemblies with reduced waste, produced in factories using renewable energy. Prefabricated assemblies (e.g. partition walls) could be designed for disassembly, so that constituting elements can be re-used.

While the CE has had traction in recent years, it has been the paradigm that humans have used for most of their existence. Aboriginals in Australia have established land-management techniques and societies that are in harmony with nature and which have been sustained for more than 40,000 years. CE principles are also present in extractive agrarian societies. The current citadel of Byblos in Lebanon was erected by crusaders by re-using centuries/millennia old stones on site, used by Romans, Persians, Egyptians and Phoenicians in other buildings. While the CE model is now being adapted to the Anthropocene, its basic principles have been around for millennia and much knowledge can be gathered by studying previous practices.

Limits to circularity

Despite the promises of a more circular construction sector, there are limits that must be considered. Firstly, if economic models are based on blind growth, even if humans manage to circulate the entirety of materials in the Technosphere, there will always be an extractive demand for more. This is magnified by increasing demand, population, and affluence in many societies.

Secondly, a more circular construction sector depends heavily on “critical mass” – a large enough amount of materials that is worthwhile harvesting and looping. With variability between buildings, lack of standardisation, and the disaggregated spatial and ownership nature of built assets, it becomes very expensive, labour-intensive, and technologically challenging to re-use existing materials. Large construction projects, such as hospitals or high-rise building, might present the critical mass for re-use, as done in ancient citadels.

Thirdly, the critical mass factor is compounded by the lack of pricing of embodied environmental flows of construction materials. It is sometimes cheaper to extract a virgin material far away, manufacture it overseas and ship it in, as compared to reusing locally. While other factors such as differences in wages and economies of scale come into play, the absence of an adequate price for embodied flows hinders deploying a circular construction sector.

Finally, the lack of knowledge and tools that enable deploying circularity in the construction sector is notable. Existing practitioners and even recent graduates are often ill-equipped in conceptual thinking and technical literacy, to deploy a circular construction sector.

Towards a more circular construction sector

While full circularity is still a mirage, measures can already help decrease resource use in the construction sector. A short list includes:

  • Educating current and future generations of practitioners to design, operate, maintain and decommission (if necessary) built assets with a circular economy mindset, drawing on knowledge from the past
  • Improving the design of buildings, notably by building smaller and reusing existing buildings and/or materials and systems
  • Devising global mechanism to internalise the environmental and social costs of extraction and embodied flows into construction materials (e.g. a global ‘carbon’ tax)
  • Better understanding existing material stocks in buildings and infrastructure, using geographic information systems, expert knowledge, artificial intelligence, and other means.

These measures, combined with a move away from growth as the sole metric for economic prosperity, a more circular construction sector might slowly start moving from mirage to reality.

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