Wanted! Building regulations to ensure design for separation and adaptation

Denmark is only 4% circular. This means that from all the materials consumed in Denmark per year, just 4% return to the economy as a recycled material – and this is significantly lower than the global average of 7.2%. These statistics were shared last year in the Circularity Gap Report Denmark, published by Circle Economy¹. For the first time ever, the report provided an overall assessment of Denmark's circularity, resource consumption, and the impacts of consumption in terms of CO₂ emissions. The construction industry is the largest contributor, accounting for a total of 31% of Denmark's material footprint and 17% of the country's total CO₂ footprint. Less than 1% of construction materials and components are currently reused.

Clearly, there is a need to improve our circularity efforts. Unfortunately, the construction and civil engineering sector is predominantly based on a linear economic model, resulting in inefficient resource utilisation and high waste production.

We particularly observe that one crucial aspect of circularity in construction is often overlooked. This concerns the 'reversibility' of buildings, meaning that buildings can be easily disassembled and components can be reused. There is currently significant focus on the primary building materials such as concrete, wood, and steel, as many development projects today emphasise optimising material use in the structural elements. This focus should continue. However, there is untapped potential in also addressing secondary building components, such as floors, ceilings, and facades, and the reuse of the materials they are made of. These materials have a short lifecycle and are therefore more frequently replaced or repaired.

Circular initiatives can reduce CO2 emissions by 38%

A study from the independent non-profit organisation, the Ellen MacArthur Foundation, concludes that circular initiatives, including design for separation, can contribute to a 38% reduction in CO₂ emissions from building materials by 2050². This significant reduction would result from the decreased demand for key materials such as steel, aluminium, cement, and plastic, all which are major contributors to carbon emissions in construction​. On a component level, a study from the Teknologisk Institut³ (Technological Institute) shows the CO₂ savings of 98-99% can be achieved for items such as windows through direct reuse.

Secondary building components are a crucial part of the circular agenda due to their shorter lifespans and modular structures. Soon, they will likely be considered to be a material bank as the chances of adjustments and replacements will be higher than demolition.

If new constructions are to be separable, it should be as streamlined and simple. This means that it should consist of limited material types and minimal layers, using the simplest assemblies possible. For example, a simple system ceiling consisting of loose plates supported by aluminium rails is far more accessible and easier to adapt and separate than a ceiling with concealed joints, which is harder to access when adjustments are needed for new functions, for damage above the ceiling, or to be demolished. Facades with suspension systems are easier to reuse than systems that are nailed or screwed, where over time it becomes more challenging to separate and reuse the materials on a 1:1 basis.

Building regulations should require reversibility

In Denmark, we currently have the ISO standard ‘design for disassembly and adaptation,’ which, based on 10 design principles, guides how buildings should be designed and constructed so that building components can be separated, reused, and recycled, extending the value of materials. We also have the environmental goals of the EU taxonomy regarding the circular economy, which evaluates the adaptability and disassembly ncentivizies of building components and materials through a point-based evaluation and percentage rating.

However, we should push for even more. The concept of materials remaining in the value chain instead of becoming waste should not only be ‘guided’ but also incorporated into Danish law. Our hope was that recent negotiations to shape the Danish building regulation for 2025 would include requirements for the ‘reversibility’ and adaptability of materials. This would mean that in addition to the carbon footprint being considered throughout the entire lifespan of a building as is currently done in the life cycle assessment (LCA) requirement, there would also be support for the possibility of reusing and recycling materials across different constructions. However, the update was published in June 2024 and unfortunately did not include any such requirements.

At present, the Danish building regulations⁴ do not consider the CO₂ and resource gains achieved by reusing materials after their lifespan. A requirement for material reversibility would ncentivize an increased focus on the individual lifespans of materials in the early design phases, enhancing the potential for reuse during a possible transformation. Just as the LCA requirement has put pressure on the project owner regarding the design parameters for a construction project, a requirement for the ‘reversibility capability’ of materials could dictate the design rather than the other way around.

Every building deserves respect. After all, in 10 to 20 to 30 years, it can contribute to parts or to the majority of another construction, avoiding CO₂ emissions and the extraction of virgin resources. If we can let materials dictate the design of individual building components and ensure a construction that can contribute to other constructions, we will support the closure of resource loops and the retention of materials in the value chain rather than becoming waste. This is a crucial step towards improving the current 1% circularity in the Danish construction industry.