The world is growing at a pace never known or perceived before. Sky-scrappers, multi-lane roads, long bridges and other infrastructures have defined the new world, shaping our lives surrounded by concrete jungles. But little have we thought about what happens to these concrete structures when they serve the purpose?
The world’s construction sector consumes at least 45% of the total global resources (Onat and Kucukvar, 2020) and about 40% of the total energy(World Economic Forum, 2016). The materials encompass a wide scope of an array from primary materials like sand, limestone, clay, soil, crushed stones, etc. to the more complex cement, concrete, steel reinforcements – each requiring strength and quality checks. The energy is consumed for several processes from the manufacture of construction materials to the making of any structure along with operation and maintenance. And in this list, let us not forget the huge volumes of fuel used in the transportation of materials.
Not just that the construction sector is super resource-intensive, it is also a party to environmental pollution. Right from the initial stages i.e., from the land acquisition and clearing for new structures, the ecological imbalance is observed. To add to this, there is significant pollution caused by quarrying for stones, manufacture of cement, tiles, sanitary ware and steel. Although most of the constructions are designed for a longer period, at the end of their service life, in many instances, these structures are demolished with little to no consideration for material recovery. Despite established construction and demolition waste management regulations in most of the countries, developing and under-developed nations suffer the perils of illegal landfilling and open dumping. Such instances have caused numerous cases of ecological damage, and destruction of the natural environment.
Certainly, suspending the development operations would not be a solution to this concern. The infrastructure projects aid in the businesses and economic development of regions. The new residential buildings are home to the growing population in cities that are inseparable from the region’s development. Not to forget the quantum 34% of the population which is employed directly or indirectly in the construction industry, whose lives depend on the growth and an increasing number of construction projects.
So, what would be an ideal way ahead?
A way which ensures the development of infrastructure as well as other structures, with minimum to little damage to nature and the environment. The concept of a circular economy gained momentum in the early 2000s. Based on the principles of industrial ecology and bio-based design, circular economy stresses process redesigning from cradle-to-grave to cradle-to-cradle. The circular economy encompasses a wide array of ideas that expand the scope of 3R – Reduce, Reuse and Recycle – to redefining the functionality of a product, to redesigning the product to be more durable, to focus on minimum usage of resources and minimum wastage, to enable material recovery at the end of the service life of a product, to facilitate sharing of resources, to encourage repair and reuse, to promote recycling and to maximize the use of renewable sources of energy (Kirchherr et al., 2017). That is, in a circular built-environment, we are no longer looking at efficient disposal of waste, but we are practising a more sustainable method of construction wherein every material is carefully selected for long term usability along with a focus on recovering these materials for reuse/recycle at the end of the service life of that structure.
Sounds a little too complicated?
Here is what it means. Let us suppose the case of concrete – the most important material for any construction. Concrete is a mixture of cement along with sand and variably sized aggregates, mixed in with correct proportions of water. In a linear model, concrete would be made using sand from rivers or beaches, aggregates from stone quarries and cement. At the end of the service life of the structure, this concrete, mixed in a composite form would be disposed of.
However, in a circular construction instead of sand, the crushed waste glass could be used, Aggregates can be replaced by granular volcanic ash, incinerator ash, rice husk or even recycled aggregates. The cement mixture can include fly ash, volcanic ash and similar materials with cementitious properties. And at the end of life, this concrete could be separated from the reinforcement and be recycled for aggregates or other materials depending on the requirement.
This was just the case of concrete. Almost every construction material can go circular, reducing the wide-scale damage to the environment as well as excessive resource depletion. Numerous countries have started to adopt a circular economy as an inclusive development ideology. The legislation on circular in built-environment draws its roots to regulatory organizations of China, like the State Environmental Protection Administration and National Development and Reform Commission. These organizations have implemented policies and regulations for the application of circular economy practices in urban infrastructure owing to the extensive resource consumption pattern in China (Fern, 2007). Following the Chinese model, in the later years Germany, Japan, and Europe incorporated policies promoting a circular economy (Merli et al., 2018). It has been proved that the adoption of circular economy in built-environment by slowing, closing and narrowing the loop by reusing materials, designing for disassembly, material substitution, and resource optimization can reduce the green-house gases emissions by at least 30% - 50% (Gallego-Schmid et al., 2020).
As a lesson from the experiences of the early adopters of the circular economy, be it any sector, multi-level stakeholder collaboration and coordination is the key to achieving the circular goal. Essentially for the built-environment or the construction sector, along with stakeholder collaboration, a clear determination of material stocks and their flows is imperative. This can enable ease in the circulation of materials as well as the sharing of resources. Another important enabler would be the development of infrastructures, such as material segregation and recovery facilities, recycling units and storage and warehousing facilities. Awareness and training workshops at all levels of working individuals on material reuse and recycling can aid in increasing the potential of optimum use of resources as well as a selection of more durable resources. Also, careful supervision at the design stage can be considered the most important step in enabling circularity in constructions. Further, governments’ influence by designing taxes and subsidies for enabling circular economy also have a great push for sustainable constructions.
Thus, we as a generation can hope that with firms’ sustainable policies and larger cooperation among the stakeholders along with suitable government interventions, the transition to a circular economy in the construction sector is very conveniently possible. It is always better sooner than later to make the circular transition.
About the Author
Purva Mhatre is a Doctoral Researcher at the National Institute of Industrial Engineering, Mumbai working in the department of Sustainability Management. My research is based on the incorporation of the Circular Economy in Built-environment.
Fern, J.E., 2007. Resource Consumption of New Urban Construction in China 11, 99–115.
Gallego-Schmid, A., Chen, H.M., Sharmina, M., Mendoza, J.M.F., 2020. Links between circular economy and climate change mitigation in the built environment. J. Clean. Prod. 260, 121115.
Kirchherr, J., Reike, D., Hekkert, M., 2017. Conceptualizing the circular economy: An analysis of 114 definitions. Resour. Conserv. Recycl. 127, 221–232. https://doi.org/10.1016/j.resconrec.2017.09.005
Merli, R., Preziosi, M., Acampora, A., 2018. How do scholars approach the circular economy? A systematic literature review. J. Clean. Prod. 178, 703–722. https://doi.org/10.1016/j.jclepro.2017.12.112
Onat, N.C., Kucukvar, M., 2020. Carbon footprint of the construction industry: A global review and supply chain analysis. Renew. Sustain. Energy Rev. 124, 109783. https://doi.org/10.1016/j.rser.2020.109783
World Economic Forum, 2016. Shaping the Future of Construction A Breakthrough in Mindset and Technology.