Circular economy. Sustainable building of the future?

Circular economy is a key factor in sustainable construction as part of the EU Taxonomy Regulation and the new Energy Performance of Buildings Directive (EPBD). It states that from 2030 onwards, buildings will only be considered "Green Buildings" if 70% of their weight is recyclable or reusable. "If I count with the mass, practically only the paint and the carpet remain, which I don't have to prove," says Michael Haugeneder, managing director of ATP sustain in Vienna, with a smile. "What I like about the concept is that it makes us realize for the first time that we actually have no resources in Europe. Everything we build here comes from supplies from other countries." The circular economy introduces a paradigm shift: resources should no longer be consumed, but kept continuously in the loop. This also stabilizes the European economy.

How can this principle be implemented in practice?
One possibility is to design building materials so they can be used for as long as possible and later reused. Resources can be kept in the loop in different ways: either as raw material (e.g., a steel beam) or as a component that is removed from one building and reinstalled in another. At ATP architekten ingenieure, we tested this approach in practice several years ago: In the large kitchen of Magdas in Vienna, doors from an old building were used for a partition wall, an old ceiling was repurposed as a sound absorber, and a steel staircase from a demolished building was reused. Such measures show that a functioning circular economy in the construction industry can already be successfully implemented. What is still missing is digitalization in many of these areas. However, the EU regulation will soon make the digital resource passport the standard for every building.

Re-use instead of recycling?
Reusing offers significant advantages over recycling, where materials have to be broken down, crushed, and reprocessed. This process is often associated with high energy, transport, and labor costs. Modular construction methods with plug and screw connections, on the other hand, allow for flexible dismantling and reuse. Many building materials are much more durable than the typical lifespan of buildings – if consistently reused, their life cycle can be significantly extended, thus making a major contribution to climate protection.

A second-hand market for building components
For reuse to become more widely adopted in construction, more than just technical solutions are needed – a seamless transparent digitalization is required to consider all aspects in planning and ultimately create a material database that can be managed later. Digital platforms could serve as intermediaries to efficiently connect supply and demand. At the same time, regulatory hurdles must be overcome, such as the lack of certification for reused materials. A standardized procedure – similar to a TÜV certification – could help in this regard. We also need dismantling guidelines and information systems on the condition of materials.

Modular construction as the key
The construction method itself is also crucial: dismantlable construction methods with modular systems, particularly in timber construction, offer promising solutions. In timber and hybrid construction, not only are the gray emissions low, but these buildings are also often easy to dismantle. However, hybrid construction with timber and concrete remains relevant – at least for a while – due to its building physics advantages. Extending the service life of building components to 100 years instead of the usual 50 years also contributes to CO₂ reduction and mitigates the gray emissions.

Healthy buildings
Another important advantage of dismantlable buildings is that all materials used in a reuse or recycling process are low in or free from harmful substances. There are no toxic foams, heavy metals, SVHCs, VOCs, or formaldehyde. However, entirely pollutant-free buildings will not be possible, as certain substances are necessary – but in quantities that are harmless to humans. Even wood contains natural pollutants, but when processed correctly, they are harmless.

A look into the future
The coming years will sustainably change the construction industry. An increasing focus on existing buildings will push new construction into the background. CO2 taxes and new regulatory requirements will make the revitalization of existing buildings more economically attractive. As a result, inventory documentation and digital planning methods such as BIM will continue to gain importance. Currently, however, there is still the issue that we legally overlook this, and as a result, the status of existing buildings is artificially disadvantaged by building law – a discrimination against existing structures.

The transition to a circular economy challenges the construction industry but also opens up great opportunities. A sustainable, resource-conserving construction method requires new processes and innovative solutions – the foundation for future-proof architecture. A key prerequisite here is that the right legal impulses are set to fairly assess both existing and new buildings, ensuring quality.