Building Without Waste: The Circular Economy in Construction

Have you ever stopped to think about the origins of all the raw materials that went into your house construction? Even for green, energy-efficient, and healthy homes, the average homeowner has very little connection to the sources of the hundreds of building materials used in the typical home construction project. The silicone in your solar panels, the gravel that strengthens the concrete in your foundation, and the average 16,000 board feet of lumber used for home framing all require mining, logging, and other processes that damage the earth's ecosystems.

Our modern, globalized society has led to an increasing distance between consumers and the sources of the products we consume. This expanding gap makes it easy for us to dissociate from the environmental and social effects of the building materials our homes require. We don't know the extent of ecosystem damage that occurred due to mining a particular raw material. Nor do we realize the social consequences of landfill waste that often borders marginalized communities.

Unfortunately, with the predominant, global linear construction model, builders, contractors, and consumers search for the lowest-priced building materials. The unintended effect of this is that these raw materials are regularly obtained with little concern for the impact on local communities and ecosystems. Though there are wood certification programs for sustainable forestry practices, contractors, homeowners, and others in the building sector don't tend to pay enough attention to the sourcing of other building materials. For instance, the copper in our electrical wires, the gold, silver, and palladium in our electronics and appliances, and even the gravel in our concrete foundation all have essentially unknown origins.

"One person's waste is another person's treasure" is the mantra guiding this economic transition. Here at Rise, we have written about how one company uses industrial waste from potato processing plants to create a unique medium-density fiberboard (MDF).

In the specific case of the building sector, a circular construction model seeks to maintain building materials, products, and resources within the economy for as long as possible. By recycling, up-cycling, reusing, and transforming waste into new, functional building materials, waste generation is minimized.  One study tells us that buildings cause a third of GHG emissions globally. They say that much of these emissions are caused by the embodied energy in building materials. Transitioning to a circular construction model would drastically reduce the embodied energy footprint of homes by limiting the need to extract raw materials for the building sector further.

Increasing the operational energy efficiency of buildings is usually considered the primary strategy for de-carbonizing our homes. A circular construction model would undoubtedly contribute to further de-carbonize the "hidden" sources of carbon emissions that come with the raw materials required for home construction.

A recent forum on the state of the circular construction model brought together leading European thinkers and experts within the building sector. The speakers shared their experiences and the perceived challenges of changing from a linear to a circular construction model.

What Are The Impacts of the Traditional Linear Construction Model?

The construction industry is a significant contributor to the environmental crises that we face today. Sophie Rosso, the deputy CEO of Redman in France, states that the construction industry is responsible for over 30 percent of the extraction of raw materials worldwide and at least 25 percent of waste in the world. In addition, when buildings reach the end of their lifetime, only 40 percent of materials are recycled or reused.  Though much focus is given to increasing our homes' energy efficiency and thermal performance to reduce energy use, Rosso mentioned that there needs to be a more critical focus on the embodied energy of the raw materials that go into our buildings. She notes that around 10 percent of global energy is used for mining "to go and find more resources so we can continue building."

A recent study determined that the global construction market is set to grow by eight trillion dollars by 2030, with the primary growth driven by China, India, and the United States. Might it be possible to meet society's needs for new homes and buildings without continuing to extract enormous amounts of raw materials?

Why Shift to a Circular Economy in Construction?

Nicolas Cruaud is the president of Néolithe, an innovative company that is creating gravel, stone, and other aggregates from non-recyclable waste. According to Cruaud, over 30 million tons of primarily un-recyclable waste is either landfilled or incinerated waste each year in France. This waste is responsible for 6 percent of greenhouse gas emissions. At the same time, around 400 million tons of aggregate (sand, gravel, crushed stone, etc.) is mined and used each year in France for construction purposes.

Recycled Aggregates Are Moving Circular Construction Forward

Néolithe has developed a way to treat non-recyclable waste and turn it into an aggregate used for construction. Following the circular construction model, this process keeps non-recyclable waste out of landfills or incinerators. It also reduces the need for further mining of construction aggregates, which are a finite resource and require enormous energy expenditures to mine and transport.

Neolith takes products at the end of the recycling chain (such as plastics) and mimics nature by turning waste into a small stone. This "fossilization" process is similar to what nature does with its waste. The resulting fossilized plastic waste, called anthropocite by the company, can be used for building roads or for any other concrete use. Moreover, instead of transporting plastic waste long-distance, Cruaud mentions the "fossilized machines" allow for relocation of waste management. Companies or communities can purchase or rent a machine to transform and revalue its problematic waste.

"Builders and real estate developers need to be trained…so that they discover that circularity is a real opportunity for their project," he says.

Similarly, Pascal Eveillard, the Sustainable Business Development director of Saint-Gobain, believes that changing to a circular construction model will not be easy. He said:

"We will have to change the whole value chain from the designer to the inspector so that everyone is engaged in thinking and designing and building in a different way. Circularity in construction represents a whole new ecosystem and a new way of thinking."

Eveillard also believes that there needs to be a focus on training small contractors and distribution outlets. "The building sector is made up of small companies, and this makes it difficult to convert to circular economy model quickly."

All speakers also believed that new regulations would be vital to promote a circular construction model.

"If we want to move the market to more circularity, we need better regulations," Eveillard says. "If we leave the market alone, just 5 to 25 percent of builders will change. Regulation needs to be explained to all stakeholders, and there is a huge need for training and to optimize the design."

Cruaud also believes that increased regulation could present an opportunity for advancing circular building materials. "We offer the same price as current waste services and raw aggregate materials," he says, "but we can't change the market on our own. We need to convince clients to give us their waste…and make owners of construction companies aware of the circular alternatives."

Despite these challenges, Cruaud is confident that most stakeholders are more than willing to transition into a circular construction model. "We don't have enemies in the construction sector as most people want to reduce their footprint," he says. "Even with the quarry owners, they know they have limited resources, and our project can allow their stone quarry products to be used for higher-value things."

Though still a marginal player in the construction industry, the circular economy model should continue to make significant strides in the coming years.

Article by:

Tobias Roberts

Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.