By replacing new materials with recycled or re- adapted ones, the construction sector can take advantage of circularity by reducing new resource production and waste.
Construction and demolition waste includes concrete, bricks, wood, glass, metals and plastic, comprising waste from the construction and demolition of buildings and infrastructure, including the planning and maintenance of roads.
A paper published last year in the Waste Management & Research journal explained that a circular economy depicted a system based on business models, which replaced linear production and disposal practices with circular ones.
It added that linear economic models were based on a ‘take, make, dispose’ mindset, implemented in raw materials extraction, onsite production, construction and disposal.
The authors said: “Circular economy replaces the end-of-life concept with reduce, reuse, recycling and other alternative waste management practices and strives in keeping products and materials ‘in the loop’.”
Key to incorporating circular principles into the built environment are sustainable design approaches that ensure a building can be deconstructed at the end of its life, with its various materials reused and recycled in a circular economy which mitigates or eliminates waste material.
It is estimated that with circular economy approaches integrated into its operations, the Australian construction industry could reduce 165 million tonnes of carbon emissions each year by 2040.
Another distinct aspect of the circular economy is adaptive reuse, which can be described as an eco- friendly process of converting an existing structure, often unused or heritage buildings, to new uses and more appropriate contemporary functions.
Sustainability is central to the design principles of adaptive reuse, as it negates much of the embodied carbon and associated greenhouse gases that are created during the construction of new buildings.
Published last year by Built, the Demystifying the Circular Economy report outlined four principles necessary to transform the construction industry from one defined by wastage to one supporting resource conservation – design for disassembly, building materials as a service, adaptive reuse, and waste as a resource.
The authors wrote: “The most important phase is the first one – how we develop materials and make key design decisions.
“We need to question the technical and functional aspects of a product, to select more durable and better performing materials, [and] to design with future uses in mind.
“How we maintain and extend – use and reuse – a product’s lifespan is also at the core of circularity.”
A number of factors are driving up the demand for recycled building materials, including higher materials costs, increasing number of construction projects, high government recycling targets, and consumer pressure for more sustainable products and practices.
The cost of conventional construction materials in Australia has been increasing for several years, while consumer surveys show nine out of 10 Australians are more likely to prefer ethical or sustainable products.
Using recycled or reclaimed building materials in construction often has lower cost than virgin materials, and allows for the implementation of a circular economy approach to construction, which minimises waste, energy use, and carbon emissions.
As awareness of the benefits of recycling construction waste grows, recovery rates have improved, but are still not widespread.
A circular approach not only reduces pressure on finite natural resources, but also reduces the amount of construction waste materials going to landfill, which has both commercial and environmental costs.
Circular buildings can be achieved through several avenues, including using durable products made of secondary, non-toxic, sustainably sourced, or renewable, reusable or recyclable materials; disassembly, reuse or recycling of embedded materials; and lifecycle assessment (LCA), lifecycle costing, and readily available digital information such as building material passports.
A material passport describes the characteristics and value of building materials and products for recovery, reuse and recycling purposes in larger volumes in open markets.
The concept is currently being developed by multiple parties, particularly in European countries, and there are several existing market tools linked to material passports, such as LCA and environmental product declarations.
Information about the material resources of a building can be useful for refurbishment purposes, or when a building is deconstructed and the products become available for other buildings or applications.
Helene Carpentier, Global Head of Circular Economy & Zero Waste at CBRE, explained that one key area in the building sector where resource consumption and waste generation were a challenge were space fit-outs, which are responsible for a third of emissions over the life of a building.
Carpentier said: “A fit-out is a process whereby interior building materials and components are installed, including flooring, wall and window coverings, partitions, doors, furniture and equipment.
“Before each fit-out, interior spaces are stripped of their components, with most products considered waste, [and] on average, fit-outs happen every eight years.
“By adopting a circular approach to building fit-outs, we can eliminate waste across the value chain and limit the negative impacts associated with the over- consumption of materials.
“There are three principles to a circular economy: design out waste and pollution, keep products in use for as long as possible and regenerate natural systems.
“Considering these principles, the built environment can reduce waste and embodied carbon while creating jobs and new capabilities locally through promoting repair, reuse, remanufacturing and closed-loop recycling.”
