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A Danish view on circular construction

As resources become scarcer, building owners may one day be able to sell walls, ceilings and floors to other developers, instead of demolishing them.


This is the vision of Danish architect Kasper Guldager Jensen, widely considered a trailblazer in circular design and construction. Guldager Jensen is founder of GXN, the innovation arm of Danish Architects 3XN that’s redesigning the Quay Quarter in Sydney by reusing 50 per cent of the existing building’s resources and the Sydney Fish Market and author of Building a Circular Future (Lead 3XN architect on Quay Quarter Fred Holt, will feature at The Fifth Estate’s Tomorrowland event on 31 October.)

Guldager Jensen is a trailblazer in circular design and construction who wants industry to see buildings as “material banks”.

“What’s interesting about circular economy is [that] it’s about economy. It’s about creating value and business opportunities,” he told The Fifth Estate during a visit to Sydney last week.

“[It’s] about connecting sustainability to business, and doing it in an industrial, scalable way.”

He says the transition to circular construction will help eliminate the concept of waste, which is a man-made problem.

“Because if you look at nature, waste does not exist … in nature you have closed systems.

“How do you transform the building industry into a man-made ecosystem? It is a big challenge but if we start doing it right, we can show the way and start seeing new business opportunities.”

Joints and connections

The transition to circular building implies that building components must be produced so that they can be cleanly separated for later reuse.

In practise, circular construction is all about the “connections, joints and system layers,” says Guldager Jensen.  For example, windows might be attached using a mechanical method rather than glue, or lime mortar might be used rather than concrete mortar.

“It’s about being able to think about the mechanics and being able to do it in reversible ways.”

Building facades are a good example. 3XN’s Circle House project – 60 social housing units in Copenhagen built to circular principles – uses four façade panels with “visible joints”. These are made of burnt reclaimed wood, demountable clay tiles, cork panels and upcycled plastic shingles (made from recovered municipality plastic) mounted on larch wood.

The panels are easy to detach and reuse and because they can be flipped, the lifecycle of the façade is doubled.

Guldager Jensen says also that circularity is not just technical in nature. Companies need to consider alternative business models such as taking back used products or leasing rather than selling materials.

The next phase of the challenge

In Europe, green building has traditionally focused on the operations side of sustainability but this is now shifting towards materials.

“That’s because now we are at the tipping point where we’re using more energy to make the material than in the cooling and operations of the building.”

Prefabrication is one way to minimise the emissions associated with construction.

“We can talk with greater knowledge about what we’ve built and also how we can reduce the amount we’re using,” he says.

Knowing what’s there is key

Digital tools play a key role in circular construction by arming designers and builders with complete and real time information about the building’s material “recipe”.

There’s already software out there today that can document where materials are in a building and in what values. It’s now also possible and relatively inexpensive to buy soft ware licences that can connect this information to a building management system, he says.

Resources shortage

Guldager Jensen says there are still a lot of resources available to the building industry but this won’t always be the case, especially in light of forecasts that the world’s building stock will double in area in the next 40 years.

There is a strong case for reducing waste over the long term, but there are also short-term benefits of this construction style. It’s about faster, cheaper, higher quality construction that’s more flexible.

“It’s about achieving price parity for faster construction, and making a building that is easy to maintain and is flexible, and then reusing all the materials in the future.”

Sydney’s Quay Quarter Tower, for example, has been designed to be highly flexible so that new tenants can easily remove or relocate components of the building to suit their needs.

Circle House © Tom-Jersø

How far away is this?

Circular construction is already gaining traction in places such as Denmark and other European countries, and in North America.

It helps that there’s been some pioneering circular construction schemes, such as the Circular House project, to prove that it can be done and at a comparable price to traditional construction methods.

Guldager Jensen says this is possible because there are enabling financial and legislative conditions in place, such as government funding and a cap on the square metre price for social housing.

He also suggests a lack of suitable financial structures is holding Australia back from the circular construction revolution. The players are already there, he says, but the financial environment is the issue, with prefabrication actually rated lower than onsite construction despite the fact that offsite construction is more precise and actually minimises risk. 

Around the world, circular construction still needs to be further developed and scaled up.

“We need industry thinking differently, about how to take buildings apart and treat them as components to be sold,” says Guldager Jensen.

This is a truly cross-disciplinary task that includes industry, government and research players, including learning lessons from other industries such as agriculture.

But it won’t be easy. “We’re essentially remaking the way we make things.”


Lead 3XN architect on Quay Quarter Fred Holt, will feature at The Fifth Estate’s Tomorrowland event on 31 October. Secure your seat now.

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