The United Nations (2010) forecast that the world’s urban population will increase by 2.7 billion people between 2010 and 2050. Built environment stocks, such as durable goods, buildings and infrastructure, are key to human development (D.B. Muller et al., 2013). They provide fundamental physical settings that the provision of basic human needs, such as food, shelter and transport, on which we rely and thus reflect the development level of society, such as urbanisation and industrialisation. These stocks also link the services humans enjoy to industrial material production and energy use in the societal metabolism (S. Pauliuk et al., 2013).
There has been rapid growth in South Africa’s urban areas, too, which has put immense pressure on the existing material resources. There is an increase in land use for infrastructure, housing, recreation, and industry (DMR, 2014). 63% of South Africans already live in urban areas, and this figure will rise to 71% by 2030. By 2050, 8 in 10 people will be living in urban areas, increasing demand for basic infrastructure. Infrastructure development should be undertaken to address the impacts of urbanisation. (PMG, 2021). Urbanisation needs to be planned; it calls for urban policies that require an understanding of the demographic changes that will happen within the city, to facilitate orderly development. The result is that in the case of South Africa, it is unclear, and the absence of planning will generate chaos (Ruhiiga, 2014).
Building and embodied carbon emissions
The growing population in urban areas has increased the demand for housing. The built environment stocks, such as buildings and infrastructure, are key to human development but also contribute to anthropogenic greenhouse gas (GHG) emissions associated with material use throughout their construction, operation and end-of-life-cycle management phases (C. Lin, 2016). This is referred to as embodied carbon emissions.
In South Africa, the non-residential and residential building sectors account for around 23% of total emissions. Based on historical trends and anticipated government programs, the likelihood is that investment in this sector will grow an average of 2% per year, between 2008 and 2050, resulting in the total building stock doubling by 2050. South Africa has policies in place to advance energy efficiency and reduce greenhouse gas emissions; however, the challenge remains translating intent into action (UNEP, 2009).
Waste and waste management in South Africa
International studies have found the construction industry to be a generally wasteful sector (L.L. Ekanayake, 2000) due to its linear approach. It is estimated that about 15% of material delivered to a construction site will end up in a landfill, while at demolition sites, about 100% of the waste generated ends up in landfills. Demolition sites usually generate the highest proportion of Construction & Demolition Waste (C&DW) (A. Aboginije, 2020).
South Africa relies on landfilling as its primary waste management system. However, landfills are running out of capacity, due to factors such as urbanisation, economic and infrastructure development, etc., according to the Department of Environmental Affairs (DEA). The disposal of C&DW in landfills negatively affects the fertility of the surrounding environment and obstructs the collection and reuse of the waste. It has become imperative to find other options to manage C&DW, especially those that can be converted into resources.
Waste management must make an essential contribution to a sustainable environment. (DEA, 2011) However, there is a significant shortage of recycling facilities at official landfill sites and a lack of administrative capacity in small municipalities, which slows the growth of the national recycling segment and hinders the government’s ambitions to achieve the objective of zero waste in landfills (Zedda, 2015).
Sustainable solutions-zero waste principles
During the last decade, the focus of researchers and policymakers addressing the construction sector broadened from reducing a building’s energy consumption in use to a comprehensive approach that considers the building’s entire life cycle (M. Buyle, 2017; L.F. Cabeza et al, 2014). According to Saghafi and Hosseini Teshnizi (2011), the most efficient method to reduce the environmental impacts of the building is to repair and reuse the whole building.
The zero-waste hierarchy is a concept that introduces ways to conserve all resources through responsible production, reuse, recycling, and the recovery of materials without burning or disposal to land, water or air that poses a threat to the environment or human health. According to the hierarchy, it is essential to rethink or redesign strategies to avoid unnecessary and wasteful consumption of materials and to make better use of, or reuse, materials on construction sites. Recycling activities should be simultaneous with material recovery, and a waste management system is not sustainable (Zero Waste Alliance, 2018).
To truly participate in the sustainable development process, it is imperative to examine all the aspects of waste minimisation across the project life cycle. The 4-Rs of waste minimisation are: Recovery, Reuse, Recycle and Reduction (P.A. Vesilind et al., 2002).
The link between waste and urbanisation
The flow of natural resources into cities and waste produced represents one of the largest challenges to urban sustainability. Circular looped metabolisms are more sustainable than linear ones. Recycling will continue to be an essential part of responsible materials management, and the greater the shift to a linear economy towards a continuously circulating materials, the greater both material gains and greenhouse gas reductions (R. Rogers, 2000). The closed-loop approach plays a significant role in achieving sustainable construction goals, as it aims to close material life-cycle loops in which waste from one process becomes a resource for another (J. Brennan, 2014).
The above image illustrates the whole-life-cycle approach for both linear and closed-loop flow. It is imperative to implement a closed-loop flow when considering the sustainability of buildings or other infrastructure, with an emphasis on embodied carbon projects and minimising this when possible. It is suggested that this can be achieved by specifying reused materials. To improve reuse and future use, it is recommended that new buildings be designed for later deconstruction, or selective dismantlement of building components, therefore maximising the quantity of material that can be recovered with minimal damage. It is recommended that this type of design practice be promoted by specific inclusion within environmental assessment methods (D.D. Densley, 2011).
This is referred to as the Design for Deconstruction approach, and it is considered to encourage a closed-loop flow as an alternative to the traditional linear process. The closed-loop approach plays a significant role in achieving the goal of sustainable construction as it aims to close material life-cycle loops in which waste from one process becomes a resource for another (J. Brennan, 2014). The implementation of the Design for Deconstruction approach during the design phase of projects plays an important role in achieving high levels of recycling and reuse while reducing the risk of cross-contamination that may hamper the recovery of useful coarse concrete aggregate at the end of the life of the buildings. Therefore, encouraging a circular economy for concrete in the South African construction industry. The construction industry plays a pivotal role in building communities and providing critical infrastructure.
How our organisation is achieving this
While the transition from a linear to a circular economy is still in its infancy, as Zutari, we have taken some strides in the correct direction. Our digital delivery approach supports circular construction principles through structured information management, BIM, ACC, ISO 19650 workflows, asset data, change control, quality management, and lifecycle records.
Circular construction depends on reliable information about what is designed, procured, installed, changed, maintained, reused, replaced, and finally decommissioned. Zutari’s digital tools support this by creating a structured digital record of infrastructure assets from design through construction and into handover or asset management. Zutari’s ISO 19650 registration also aligned information management and Autodesk Construction Cloud to control project information through defined stages, namely reference information, work in progress, shared information, published information and archived records. The ACC procedure confirms that published information may be used for construction or asset management, while archived information is retained as built drawings, design stage approvals, reports, calculations, as constructed models, change audits, asset data, operation and maintenance information, and health and safety records. This is directly relevant to circular construction because these records enable future maintenance, repair, refurbishment, reuse decisions and lifecycle planning.
Although some of our policies thus far do not directly link to circular construction, there are documented processes that support its core principles. These include reducing design and construction waste, avoiding rework through clash detection and coordinated model reviews, improving the reliability of asset data, retaining as-built information, recording change audits, supporting operational and maintenance planning, and enabling future refurbishment, reuse and lifecycle decision-making. In this context, Zutari’s digital delivery process serves as an enabling platform for circular construction, preserving the information needed to keep assets and materials in productive use for longer and to make informed decisions over the full infrastructure lifecycle.
Additionally, Zutari’s implementation of digital tools across the infrastructure lifecycle supports circular construction by ensuring that infrastructure information is created, checked, coordinated, approved, published and retained in a controlled digital environment. Through BIM, Autodesk Construction Cloud, ISO 19650-aligned workflows, structured naming conventions, metadata, review workflows, issue management and archived asset records, Zutari creates a traceable digital information environment that extends beyond design and construction into asset management, operation and maintenance.
Conclusion
As such, to improve the recovery and reuse of recycled concrete aggregate, South Africa should adopt a Design for Deconstruction approach at the early design stage of projects. This requires integrating
