Circular economy – resource-efficient construction

Enormous amounts of natural, finite resources are used in the construction, operation and demolition of buildings. About a third of global resources are consumed by the built environment.¹ In Germany, construction materials account for half of all raw materials extracted.² This corresponds to an annual per capita consumption of 187 tonnes.³ On top of this, we need to consider the large amounts of waste that buildings generate during their life cycle. Between 2015 and 2019, construction and demolition waste increased by 10% to over 230 million tonnes – and the trend continues to rise.⁴

In a world increasingly confronted with a scarcity of resources, environmental pollution and the consequences of climate change, the concept of the circular economy is gaining in importance. In contrast to the traditional, linear economic model, which is based on the principle of “take – make – throw away”, the circular economy takes a holistic approach: the aim is to extend the life cycle of products, keep materials in circulation and largely avoid waste. As such, the circular economy is not only an answer to environmental challenges, but it also opens up new economic opportunities for innovative business models, resource efficiency and sustainable design.

Operational emissions from buildings are constantly increasing over time. So far, the use of “green electricity” from renewable energy sources has been one of the most effective ways to reduce these emissions. However, to take a decisive step towards the circular economy, a more holistic approach is needed: calculations should not only take into account operational greenhouse gases, but also the entire life cycle of a building – from the product, construction and use phases through to end of life. Life cycle assessments (LCAs) examine all CO₂ emissions arising throughout the various phases. The 2024 EU Energy Performance of Buildings Directive (EPBD) sets out requirements for the overall efficiency of buildings and makes it mandatory to take the greenhouse gas potential into account throughout the entire life cycle: from 2028, new builds with more than 1000 m² of usable space will have to document this potential in their energy certificate; from 2030, the regulation will apply to all new builds. This will make the holistic life cycle assessment the standard and a key component of sustainable building planning.

When considering material-related and operational greenhouse gas emissions over the entire life cycle of a building – typically over a period of 50 years – we can see that a significant proportion of total emissions occur during the initial phase in particular, i.e. during the product and construction phase. This means that the central question must be addressed from the outset of the construction process: which materials are to be used? To record in detail all building materials required in a building, the use of digital material registers is becoming increasingly important; they not only enable a high degree of transparency with regard to the resources used, but also facilitate the digital planning of the construction process, including the calculation of the expected grey emissions. Already in the planning phase, the materials used should be selected on the basis of this data in such a way that if the building is dismantled at a later stage, the building materials can be individually extracted and reused.

After the planning phase, a material passport is created – a digital instrument that systematically records and documents the materials and products used in a building. The material passport acts as a digital image of the building’s structural fabric and makes it possible to determine the energy design and equilibrium points, and to track the life cycle of materials. This encourages the reuse of resources and reduces waste. As a result, the climate footprint and profitability can be improved, and buildings can be set up as a “commodity bank” from the outset.

Material passports and material registers also play a key role in the implementation of the EU Energy Performance of Buildings Directive (EPBD), which aims to achieve a fully emissions-free building stock by 2050. Thanks to these digital tools, it is possible to track which building materials have been used in a building. This transparency creates the basis for a comprehensive assessment of a building’s energy efficiency and promotes a resource-saving, circular construction method. This is also important because it can be assumed that investors and financial institutions will pay more attention in future to the materials used in the buildings.

The circular economy in construction offers considerable economic potential. It not only enables materials to be reused and resource consumption to be reduced, but also contributes to the reduction of CO₂ levies, the minimisation of devaluation risks and the better utilisation of available subsidies. It also makes real estate more attractive in terms of rentability and financing.

As digital documents, material passports make an important contribution to this by creating transparency over the materials used and providing investors and financial institutions with evidence that the building stock is being decarbonised. They also help to identify and reduce transitory risks in the transition to a climate-neutral economy at an early stage.

¹ Global Alliance for Buildings and Construction, 2019: Global Status Report for Buildings and Construction
² Statistisches Bundesamt (Details), 2017: Umweltnutzung und Wirtschaft. Tabellen zu den umweltökonomischen Gesamtrechnungen. Teil 4. Daten für das Jahr 2015
³ Wuppertal Institut, 2017. Klimaforum Bau, 2021
⁴ Statistisches Bundesamt (Details). Abfallbilanz 2019 und 2015