Circularity
Sustainability

Design for reuse: a key element of sustainable buildings

Susanne Dyrbøl
Susanne Dyrbøl
27 August 2020

It’s time for building design to look beyond the present and consider how materials and components of a building can be reused or recycled to make other buildings.

Circular house prototype by Tom Jersø

When it’s finished sometime in 2023, the Circle House project located outside the city of Aarhus, Denmark will achieve something not many other housing projects can claim: a circular building model.

What does that mean? All 60 of the Circle House housing units are designed so that 90 percent of the materials can at some point in the future be reused or recycled at high-value to make other buildings.

Designing and constructing durable and resilient building that are worth more than the sum of their present-day parts is a theme we are seeing more of today, and for good reason: Countries around the world are looking for the most effective ways to meet climate goals while also accomplishing social and economic ones, including affordable housing, job creation and improved quality of life.

Built to last, and last

There is no single definition of a sustainable building or system, but the following are some of the most important credentials of sustainable architecture:

  • Designed to operate with very low energy demand
  • Designed for fire resilience and reusability
  • Consideration of the resources required for the lifetime of the building

The World Green Building Council (WGBC) defines a ‘green building’ as a structure that aims to reduce or eliminate its negative impacts on the environment. It includes considerations for the preservation of precious natural resources and the construction, habitation and demolition of the property. These practices can also have positive impacts, including sustaining the economy and improving the quality of life for citizens.

In the EU, a variety of countries have started to integrate sustainability parameters on a voluntary basis in national building codes. For example, France, Denmark, Germany and the Netherlands have created their own rating systems to encourage more sustainable development.

Buildings as material banks

A recent report from Material Economics, a management consulting firm specializing in sustainability, finds that reuse and recycling of building materials represents a massively underappreciated avenue for reaching global climate goals.

How massive? In the EU alone, the construction sector consumes 1.6 billion tonnes of materials annually, and specifically 33 percent of all steel, 20 percent of plastics, 25 percent of aluminum and 65 percent of all cement.

In the report, The Circular Economy – a Powerful Force for Climate Mitigation, Material Economics finds that a circular model that focuses on reusing these materials to make needed buildings would help EU heavy industry get halfway towards its net-zero goals. Construction is responsible for one-third of global waste every year, designing buildings as future material banks for other buildings would drastically reduce this. 

In the EU, buildings account for 40 percent of final energy demand and 36 percent of CO2 emissions. Up until now, most discussions of the CO2 impact of buildings have focused on the “use phase” of the buildings, especially concerning energy consumption. However, according to the Material Economics report, around 15% of total lifecycle CO2 emissions from EU buildings today are attributable to materials and construction.

As greater energy efficiency and use of low-carbon energy help reduce energy emissions, the CO2 ‘embodied’ in buildings will become ever more important as we move towards nearly-zero-energy buildings. It should be one of the key questions to consider when designing durable buildings or when a demolition is being considered as an alternative to a renovation.

Today 60 houses, tomorrow entire cities

For Kasper Guldager and the others involved in Circle House, the findings in the Material Economics report are not news, at least not the message that sustainability in the construction industry requires that we see all of our buildings (and design them) as more than the sum of their parts.

Kasper Guldager talks about circularity and the role of buildings in meeting climate goals (2 min)

The Circle House project is a close collaboration of four architecture firms and more than 30 suppliers and partners, the city of Aarhus and the customer, Lejerbo housing association. The project is financially supported by different innovation programs. The broad coalition is an indication of the enthusiasm for the project’s goal but also one of the many realities and challenges of designing and building in an entirely new way. 

“Circularity as it applies to architecture and construction is about rethinking the built environment; its building materials, construction methods and liveability,” says Guldager. “We don’t have the resources on the planet to continue as we are. We have to change our linear building process and explore different business models and systems that among other things support reuse of building components and recycling of materials. We hope the Circle House project can become a circular building model for others to learn from and be inspired by”.