As of 2020, the global population is estimated to be 7.8 billion people, a marked—and for many, alarming—increase from the 7.2 billion of 2015. For wealthy countries, population growth has seen an increasing demand for residential housing that is beginning to outpace supply, as well as outgrow traditional approaches to a city's planning and infrastructure.
Australia is one such country that faces this issue. Its cities grow overcrowded they are built up, forming denser and more compact urban landscapes.
To accommodate rising demand, housing supply must grow rapidly—yet building industry, for the most part, continues to fall short of environmentally friendly practices. With climate and population growth crises working in tandem, the need for the building industry to adopt greener construction practices becomes crucial for a sustainable future. Increasingly, it is also becoming evident that simply focusing on greener design trends and building energy-efficient homes is not enough.
Systemic change is required, one that focuses not only on the operations of a home but looks at the foundations of a house: the materials that go into its construction.
The economics of waste reduction
For Danish architect Kaspar Guldager Jensen, the solution to waste reduction is through the establishment of a system for circular buildings. He proposes a model that joins economy and sustainability, envisioning a future where the building industry is transformed into a 'man-made ecosystem'; he notes that, in nature, ecosystems do not produce waste. They are closed systems, and that is what he hopes circular construction can achieve.
In practice, circular construction is about 'connections, joints, and system layers'; it is about the mechanics of construction, and 'being able to do it in reversible ways'. That is, reusing and recycling materials. Considering, for example, the demolishment process of a building.
After demolishment: where does it all go?
Five significant materials go into building construction: steel, glass, drywall, concrete and flooring.
Steel — is mostly recycled, as is clear glass.
Coloured glass — however, is destined for landfill.
Drywall — in theory, is a highly recyclable material. It simply requires some careful planning in its removal, as drywall is only recyclable if it remains intact.
Flooring — is more complex. Carpet tiles for example, must be removed as cleanly as possible, the backing is usually made up of cheap components that contaminate high-value plastics, rendering the material useless if the flooring is not removed with care.
Concrete — which requires one of the most carbon-intensive production processes, is downcycled, however only if its core materials present downcycling as a feasible, financially efficient option. And a large proportion of it is not, as the concrete used in the construction of buildings is usually full of contaminants and other materials which present a safety risk (as well as requiring a complex process to sort recyclable material) in its recyclability into new products.
As such, much of these materials which can be recycled or reused with more effort are instead waste products. We currently sit at a tipping point, however, where the environmental cost of material production can no longer be ignored.
The core idea of circular construction tackles this problem—it seeks to establish a sustainable system that extends the life-cycle of building material by revising our approach to its production and implementation processes; to feed old building materials into new buildings in a closed system of construction.
Circular construction in Australia
In Europe and North America, circular construction has gained popularity in recent years. Propped up by financial and legislative conditions, as well as government funding, circular construction, in those regions, is being slowly cultivated by a steady, if small, trickle of support.
For Australia, however, such support is absent entirely. Guldager Jensen believes that while interest is here, the opportunity has not yet presented itself. For circular construction to become established as a legitimate, practicable idea in Australia (as well as to improve its legitimacy internationally), a change in policy is required.
More broadly, it requires a change in the way we approach our building industry. For in integrating the principles and methods of circular construction, we are 'remaking the way we make things'. (ET)