Circular economy in construction

According to estimates, the construction industry accounts for around 40 per cent of global CO₂ emissions and produces around 60 per cent of global waste. This means that over 2 billion tonnes of construction waste are currently generated worldwide every year. It is the equivalent of a 10-metre-high mountain of rubbish covering the area of Berlin. And by 2050, this figure could rise to over 3.5 billion tonnes per year if no action is taken.

"The linear economy has been fuelling the problem for decades: take-make-waste at ever faster intervals. If we think this through to its logical conclusion, we will suffocate in our waste (including CO2) before we run out of raw materials," says Annette Hillebrandt, architect and professor of building construction, design and materials science at the University of Wuppertal, who advises the German Federal Environment Agency on sustainable construction.

The production of cement and concrete requires immense amounts of sand, water and energy. The logistical challenges exacerbate the problem: components and materials, as well as products, are flown in, shipped and transported from all over the world. The result is long transport routes, high emissions and corresponding costs.

From disposable architecture to a circular economy through sustainable use of materials and urban mining

Unfortunately, in many places, including in Germany, wasteful ‘disposable’ architecture is still being developed for single use. Instead of ending up as rubble and waste that is expensive to dispose of, buildings could be recycled as ‘urban mines’. Materials such as metals, easily dismantled wooden wall elements, large-format facade panels made of natural stone and glass, or even natural oak floorboards could be resold. It is therefore worthwhile in every respect to rethink our approach and move towards renovation instead of new construction, mandatory circular building concepts, and the increased use of environmentally friendly, reused and recycled building products, reversible construction methods and resource efficiency.

Best practice and case studies

There are already some successful examples of circular and sustainable architecture from recent years. These include the Danish ‘Circle House’ project, which is made from 90% reusable materials and designed according to the principles of the circular economy.

In the case of the Triodos Bank in Driebergen-Rijsenburg, Netherlands, a completely demountable building with a modular design has been erected. It provides a habitat for insects and temporarily stores rainwater, thanks to its green roofs. All materials used here are also recorded in detail in a digital material passport.

Let’s move on to The Cradle in Düsseldorf, the first hybrid timber office building designed using hybrid timber construction methods. All building materials used here have been tested and selected for their material health, purity and separability so that they can be reused or returned to the material cycle after use.

How EU taxonomy and building passports are accelerating progress

The EU taxonomy, a system for classification and categorisation, forms an important basis for the EU's planned building resource passport, which is intended to enable the complete documentation of a building's components in order to ensure the efficient reuse of materials and components during subsequent demolition. The German Sustainable Building Council (DGNB) has already developed a proposal for such a passport.

The building passport is not yet mandatory across the board, but cooperation agreements are already in place in North Rhine-Westphalia, for example. And the new German government has made it clear in its 2025 coalition agreement that the building sector plays a key role in achieving climate targets.

The construction industry has enormous potential – Europe's chance to become an innovation leader

The European Green Deal is a comprehensive strategy that aims to make Europe climate neutral by 2050. Europe could play a pioneering role in developing sustainable economic practices by focusing on green technologies, increasing resource efficiency and promoting an innovative circular economy.

The fact that materials and raw material/property values can be digitally linked opens up completely new possibilities for economic efficiency and monetisation. There are an increasing number of digital platforms, certifiers and service providers for whom this sector offers a basis for promising and innovative business models (see examples below). The transition to circular construction is therefore not only ecologically sound, but also economically viable. It is up to us to transform ourselves from one of the world's largest consumers of resources to a world leader in sustainable construction!

baubook.info:
https://www.baubook.info/de
Platform that collects and manages information on building materials and buildings to support reuse.

BauKarussell:
https://www.baukarussell.at/
Expert advisor and provider for social urban mining and used building components.

Concular:
https://concular.de/
Provides a digital platform for circular construction and material management, with a focus on the reuse of materials from existing buildings.

Genbyk:
https://genbyg.dk/
Denmark's largest DIY store for used building materials. For second-hand construction, home and garden.

Materialnomaden:
https://www.materialnomaden.at/
Services for evaluating materials and building components and creating feasibility studies and component catalogues to assess reuse potential.

Restado:
https://restado.de/
Online marketplace specialising in the reuse of building materials, offering both used and new materials.

RotorDC:
https://rotordc.com/
Cooperative that organises the reuse of building materials. Dismantling, processing and trading of reusable building components.

Use again:
Swiss platform for building materials and expertise in waste reduction and reuse.