Designing Out Waste: A Call for Circularity
We are living in a period of environmental breakdown: a climate emergency, mass biodiversity loss, pollution and extinction, the over-utilisation of natural resources and a global waste crisis. There are an increasing number of complex global risks accelerating our planet’s breakdown, and it is undeniable that our current linear systems which extract, transform and use materials are causing immeasurable damage to the planet and its people.
The Shape of our Economy
Globally, our linear take-make-waste systems are putting us on track to environmental, social and economic disaster, with the use of materials and products trending in a dangerously unsustainable direction — 2023 estimates predict the world is only 7.2% circular (a reduction from 8.6% in 2020 and 9.1% in 2018). Today, high-income countries are generating more than one-third of the world’s waste, yet they only account for 16% of the world’s population. In lower-income countries an estimated 93% of waste is illegally dumped, and by 2050 waste generation in Sub-Saharan Africa is expected to more than triple from current levels.
An estimated 2 billion tonnes of municipal solid waste was generated in 2016, and in 2050, this number is expected to grow by 70% globally to 3.4 billion tonnes. In 2022, a year’s worth of biological resources were used in just seven months, which means the equivalent of 1.75 planet Earths would be required to supply this level of demand per year. Today, five of the nine key ‘planetary boundaries’ that measure environmental health across land, water and air have been broken.
Today’s efforts to combat climate change have focused predominantly on the critical role of renewable energy and energy-efficiency measures within the built environment; these measures would address 55% of emissions from the sector. However, meeting climate targets will also require tackling and prioritising the remaining 45% of emissions associated with the things we make, including building materials.
All stakeholders in the built environmental value chain have a role to play in enabling circular solutions at scale. Circular design and construction offers extensive environmental opportunities and socio-economic benefits if the appropriate design and construction strategies are implemented. In practical terms, it requires all stakeholders including investors, clients, developers and design teams to take a longer-term view, considering the past, present and future use of a building’s products and parts.
Circular Buildings
Building operations and the materials used in the construction of buildings are estimated to account for around 37% of global CO2 emissions.
Our homes, localities and infrastructure cover less than 2% of the earth’s surface, yet our cities produce an estimated 70% of all global greenhouse gas emissions and consume almost half the resources extracted globally. Once a city is built, its physical form and land-use patterns can be locked in for generations, leading to unsustainable sprawl. Projections suggest this trend is only accelerating, with estimates stating that 68% of the world’s population will live in cities by 2050. Today, the expansion of urban land consumption outpaces population growth by as much as 50%, which is expected to add 1.2 million km² of new urban built-up area to the world by 2030.
High-income countries are generating more than one-third of the world’s waste, yet they only account for 16% of the world’s population. In lower-income countries, an estimated 93% of waste is illegally dumped, and by 2050 waste generation in Sub-Saharan Africa is expected to more than triple from current levels. An estimated 2 billion tonnes of municipal solid waste was generated in 2016, and in 2050, this number is expected to grow to 3.4 billion tonnes— that represents an increase of 70%.
The transition to a circular economy within the built environment will bring together resource efficiency and opportunities to decouple economic growth from carbon emissions.
Globally, the circular economy could yield up to US $4.5 trillion in economic benefits between today and 2030. In Europe alone it is estimated that a transition to a circular economy could generate a net economic gain of €1.8 trillion per year, this represents a potential 7% increase in the region’s GDP.
A Definition for a Circular Building is: A circular building optimises the use of resources whilst minimising waste throughout its whole lifecycle. The building’s design, operation and deconstruction maximise value over time using:
- Durable products and services made of secondary, non-toxic, sustainably sourced, or renewable, reusable or recyclable materials
- Space efficiency over time through shared occupancy, flexibility and adaptability
- Longevity, resilience, durability, easy maintenance and reparability
- Disassembly, reuse or recycling of embedded material, components and systems
- Lifecycle assessment (LCA), lifecycle costing (LCC) and readily available digital information (such as building material passports).
WASTE
Implementing circular economy principles and approaches is essential when designing out waste. By using resources efficiently from the design stage, the aim is to plan to use available materials as efficiently as possible to minimise the amount used during an asset’s construction and operation.
Sustainable waste management closes the loop by reusing and recycling as much waste as possible, allowing it to re-enter the economy instead of being sent to a landfill. A circular economy depends upon using materials to their most efficient extent, and waste management is the last step in that process.
Where waste is inevitable and products are not practically reusable, careful consideration must be given to achieve optimum use of all waste streams. Best practice waste management plans for construction must be prepared in the early stages of a project, considering waste as a valuable resource. Environmental impacts are reduced when the contractor diverts a targeted percentage of construction and demolition waste from landfills. Equally, an appropriate plan for operational waste should be prepared that ensures the building design includes adequately sized waste storage areas to facilitate efficient, safe separation, collection and recovery.
A circular economy is only possible with sustainable waste management systems. Adopting a zero-to-landfill approach is a specific, measurable and achievable target. However, it is also essential to have transparent, published data on the recovery and destination markets available for all materials and products.
The Waste Hierarchy:
To minimise the negative impacts of waste, the Waste Hierarchy was proposed as a model to establish preferred programme priorities and evaluate processes that protect resources.
The European Commission, for instance, developed a five-step “waste hierarchy” for the EU Waste Framework Directive, in which preventing waste is the preferred option, and sending waste to landfill should be the last resort.
The Directive highlights waste management principles, such as:
- avoid endangering human health and harming the environment,
- avoid risking water, air, soil, plants or animals,
- avoid causing a nuisance through noise or odours, and
- avoid adversely affecting the countryside or places of special interest
It explains when waste ceases to be waste and becomes a secondary raw material, and how to distinguish between waste and by-products. The Directive also introduces the “polluter pays principle” and the “extended producer responsibility”.
Organisations such as the United States Environmental Protection Agency follow a similar hierarchy and highlight the potential of energy recovery. Converting non-recyclable waste materials into electricity and heat generates a renewable energy source and reduces carbon emissions by offsetting the need for energy from fossil sources, and reduces methane generation from landfills. After energy is recovered, approximately 10% of the volume remains as ash, which is generally sent to a landfill
Minimising waste at deconstruction, Kāinga Ora — Homes and Communities
Construction and demolition waste may represent up to 50% (6 million tonnes per year) of all waste to landfills in New Zealand.
Consequently, the municipality of Kāinga Ora established an ambitious deconstruction and demolition programme, which aims to reuse or recycle up to 80%, or more, of uncontaminated materials by weight in Auckland and Northland development areas, and 60% of uncontaminated materials in all other regions.
The programme prioritises house relocation and deconstruction over demolition, wherever possible. Relocation enables a whole house to be repurposed, while deconstruction allows for greater reuse of materials. In 2021, Kāinga Ora expanded the relocation programme to cover at least 7% of all public houses removed from development areas nationally. These targets complement the Kāinga Ora Environment Strategy which includes a range of initiatives to reduce the impact of construction and demolition on the environment.
The Kāinga Ora municipality completed its first public housing deconstruction project, where 8 houses were removed using deconstruction at a Mount Albert development in Auckland. The project achieved 85% diversion from landfill, diverting 203 tonnes of building construction and demolition waste. What’s more, the cost and duration of the deconstruction were found to be similar to conventional demolition.
Is this the End, or the Beginning?
In the natural world, nothing goes to waste. It is undeniable that humans, with our current linear systems which extract, transform, use and waste materials, are causing immeasurable damage to ourselves and the planet.
The use and waste of materials and products is trending in a dangerously unsustainable direction. Our homes, localities and infrastructure cover less than 2% of the earth’s surface, yet our cities consume almost half the resources extracted globally. Current estimates are that the world is only 7.2% circular, and continually overshooting planetary boundaries.
A circular economy is an essential part of the sustainability solution. All governments and the building and construction sector must prioritise the massive material and waste footprint of our current linear system and embrace a circular transition that leverages social value for all. The transition to a circular economy within the built environment brings opportunities to decouple economic growth from carbon emissions and could yield up to US $4.5 trillion in economic benefits between today and 2030.
