Circularity

The construction industry is one of the most resource-intensive sectors in the world. The most important raw materials in construction, non-metallic mineral resources, account for nearly half of the global raw material demand (Circle Economy, 2023). At the same time, the construction industry generates more than one third of all waste in the EU. The current system of material extraction, use and subsequent disposal is known as the linear economy.

The raw materials we use are limited, however. And renewables can only cover part of the demand, as more resources are consumed than can be sustainably produced (Circle Economy, 2023). At the same time, the world’s natural deposits of non-renewable raw materials are being continuously depleted. Sand, one of the most important materials in the construction industry, is the second most consumed raw material globally after water (bvse, 2020). And as more and more raw materials reach the end of their useful life, Europe’s dwindling landfill capacities are increasingly becoming a problem. The result: higher costs for both the purchase of materials and for disposal services.

Solving the challenges of the linear economy and ensuring the availability of sufficient raw materials in the future requires a successful transition to a circular economy. In a circular economy, the life cycle of materials and products is extended by keeping them in the economic cycle and at the highest possible quality for as long as possible, even after the end of their regular service life. This also avoids the generation of waste.

Circularity in the construction industry

STRABAG, having recognised the potential of the circular economy, has responded by setting goals and developing business models that cover the entire value chain. This includes aligning ourselves with the 9R framework of circularity: Rethink, Reduce, Reuse, Repair, Refurbish, Remanufacture, Repurpose, Recycle and Recover.

This broad spectrum is also an advantage for our clients, as the high level of vertical integration within our Group helps to counter the risks of raw material shortages, price peaks for building materials and bottlenecks in waste disposal services.

Increasing product and material efficiency

Improved design and alternative construction methods can significantly optimise a building’s material efficiency and environmental footprint. Modular construction, using the highest possible degree of prefabrication, also ensures that less waste is generated during production while also reducing construction times and simplifying the deconstruction process. Optimised construction planning using LEAN methods and specific analysis tools allows us to continuously examine how construction sites can be designed more efficiently and how materials can be used as economically and as intelligently as possible.

We are also conducting research into alternative building materials with increased resource efficiency and a more favourable environmental impact (see Projects and initiatives). STRABAG also produces its own building materials and operates quarries as well as asphalt and concrete mixing plants where new building materials can be tested under normal production conditions..

Extending the useful life of our products

Using buildings for as long as possible, refurbishing or modernising them instead of tearing them down, is the resource-saving alternative to the construction of entirely new buildings. To support our clients in this endeavour, we are continuing to expand our expertise in the field of reconstruction, conversion and refurbishment. The increased refurbishment of existing buildings and infrastructure also helps to ensure that less land is sealed through paving and the construction of new buildings. This keeps existing ecosystems intact.

In cases where deconstruction may be required, it is best if these works are already taken into consideration during the design and planning phase. This makes it easier to reuse parts of buildings following the end of their useful life. Prefabricated concrete elements are particularly suitable for this purpose. Staircases and elevator shafts are produced in one piece, are very durable and have standardised dimensions, so they can usually be removed and reused with little effort.

Building with recycling in mind and closing material cycles

True recycling means keeping materials in the cycle in as consistent a quality as possible instead of disposing of them. This systematically reduces the consumption of primary raw materials and lowers energy costs. When realising new construction projects, the aim must therefore be to use secondary raw materials as much as possible. One of the ways in which we are optimising our material flows is to connect our construction sites and improve the data basis for material use and waste generation.

An important key to the successful use of secondary raw materials is urban mining. This means viewing densely populated areas – especially large cities – as enormous raw material repositories. Long-lived goods in particular, such as concrete or asphalt, aren’t demolished and hauled off for disposal, but recycled on site and reused as new secondary material. Information on some of the strategic partnerships between STRABAG and start-ups in the field of urban mining can be found in the Projects and Initiatives section.

Wherever waste is generated, it should be reused in the highest quality possible. For this reason, STRABAG has its own entities that specialise in the recycling and disposal of waste. One of these is the recycling and processing centre for mineral construction waste currently being established in the German city of Bremen. Plans for these so-called C3 centres at other locations are already underway. We also remediate and operate landfill sites specifically for our customers. Our range of services further includes the reutilisation of waste from waste treatment, the remediation of contaminated soils and the treatment of groundwater and construction site water. In this way, we contribute to the downstream utilisation of waste and the conservation of natural water resources.

Rules, responsibilities and due diligence

The central staff division Business Compliance & Management Systems is in charge of the Group’s environmental management system, which is regularly audited both internally and externally. Around 93% of STRABAG’s entities are certified to ISO 14001 or EMAS. Compliance with environmental protection is assessed during audits at our various facilities and construction sites.

In accordance with the respective regulatory requirements, waste management officers and waste disposal officers have been appointed at our facilities and specialised waste management operations. They are responsible for the implementation of the national laws and regulations regarding the handling of waste and hazardous substances and the use of secondary raw materials. Here, too, legal conformity is regularly reviewed both internally and externally through audits in accordance with the applicable management systems.

Opportunities and risks with regard to circularity are also reviewed and assessed as part of the reporting process. The aim is to monitor challenges and seize opportunities at an early stage. In the 2023 financial year, we began to focus more on circularity and on reconstruction, conversion and refurbishment with the establishment of specialised entities as a way to further expand circular construction methods and business models within the Group.

Objectives

Circularity is one of six key strategic topics that has been firmly anchored in our Strategy 2030. We want to expand our expertise in the procurement and handling of building materials, as well as in dismantling and recycling, in order to continuously increase our resource efficiency.

The Group-wide environmental and energy policy was also revised during the 2023 financial year. Our environmental and energy policy forms the foundation for environmental management at STRABAG and specifies the overarching goal of circularity: to promote and advance the transition to a circular economy, in particular through methods of circular construction. To do so, we must minimise the consumption of energy and of primary raw materials and avoid waste. The following measures should help us realise these goals:

We consider buildings over their entire life cycle. Using building-specific life cycle assessments and the evaluation of circularity, we identify potential for improvement and demonstrate the ecological added value of building variants to our clients.
We develop end-to-end material and waste concepts and are introducing a Group-wide waste management system that also includes the handling of hazardous waste.
We are continuously increasing the percentage of recycled materials in our products and are investigating the use of alternative, renewable building materials. We also strive to continuously reduce water consumption in our company processes.
During the design and build phases of our projects, we consider not only the origin of the materials used, but also their possible uses at the end of their service life. The materials and components used should be removable, separable and reusable or recyclable.

Indicators

Eingesetztematerialien

We report the six largest material flows by volume, showing materials that are used to manufacture our products and provide our services.

Materials used¹

Material	Unit	2019	2020	2021	2022	2023
Stone/gravel	thousands of tonnes	70,410	69,960	64,790	59,991	56,626
Asphalt	thousands of tonnes	13,270	12,745	12,715	12,056	11,850
Concrete	thousands of m³	5,519	5,089	4,775	5,154	4,576
Cement	thousands of tonnes	1,642	1,739	1,555	1,239	1,200
Structural steel	thousands of tonnes	477	447	445	464	455

1The volumes were calculated from the average prices.

Shown below is the percentage of recycled asphalt added during production of asphalt mixtures in Germany, Austria and Poland (share of Group output approx. 69%). The previous year’s figures (2022) for Poland and Austria were adjusted retrospectively due to a change in the calculation method.

Germany: 34% out of a total asphalt mixture production of 3,306 thousand tonnes (2022: 35% out of 3,036 thousand tonnes)
Poland: 7% out of a total asphalt mixture production of 2,525 thousand tonnes (2022: 6% out of 2,268 thousand tonnes)
Austria: 16% out of a total asphalt mixture production of 954 thousand tonnes (2022: 15% out of 1.077 thousand tonnes)

Abfaelle

The largest waste streams in the Group result from mineral construction waste. Waste from production and administrative sites as well as non-mineral construction waste passed on to certified specialist waste management companies play a subordinate role. This is typical for the construction sector and distinguishes it from other branches of industry. The total amount of waste depends on the size and type of the construction project (e.g. buildings, transportation infrastructure, dismantling work, excavations, recycling activities) and on quality specifications. Since these specifications are determined by third parties, STRABAG has only limited influence on them. In this management approach, the total quantity is therefore not defined as a controllable variable. In the future, we will measure the waste targets stated above using the indicators listed in the following tables.

Handled waste includes mineral waste that STRABAG accepts/processes in the course of its project business and in its own waste and recycling management centres and processing sites and feeds into the various streams of preparation for reuse, recycling or other processes for recovery and disposal.

Disposal refers to all processes that do not involve recovery.

Mineral waste that is diverted from disposal includes waste that is prepared for reuse, recycled and entered into other recovery processes.

Preparation for reuse includes mineral waste that is prepared for reuse with the same purpose as originally intended – e.g. through washing, screening or sorting.

Recycling refers to the reprocessing of mineral waste in order to obtain new materials and return them to the production cycle.

Other recovery processes comprise all other recycling methods.

On site describes waste that is recycled or disposed of by waste management companies belonging to the Group.

Off site describes waste that is recycled or disposed of by external waste management companies.

Total handled waste by composition (t)

	Total handled waste (input)	Waste diverted from disposal	Waste directed to disposal
Total waste	9,279,999	3,989,724	4,344,627
Non-hazardous waste	8,840,369	3,801,681	4,060,780
Hazardous waste	439,630	188,043	283,847

Waste diverted from disposal (t)

	Total	Onsite	Offsite
Total waste	3,989,724	1,761,562	2,228,163
Non-hazardous waste	3,801,681	1,576,373	2,225,308
Preparation for reuse	232,208	8,550	223,658
Recycling	238,174	238,174	0
Other recovery operations	3,331,299	1,329,649	2,001,650
Hazardous waste	188,043	185,189	2,855
Preparation for reuse	2,855	0	2,855
Recycling	0	0	0
Other recovery operations	185,189	185,189	0

Waste forwarded for disposal (t)

	Total	Onsite	Offsite
Total waste	4,344,627	338,224	4,006,402
Non-hazardous waste	4,060,780	329,071	3,731,709
Hazardous waste	283,847	9,154	274,693

The data in the tables comprise the values from the corporate entities in Austria and from projects and orders in Germany which the Environmental Technology and Building Materials/Recycling subdivisions were responsible for in the reporting year. Local legislation requires these entities to report their waste streams. Data collection was extended to other companies at the beginning of 2024. A new structure for waste and recycling management postings was created within STRABAG’s ERP system for this purpose. Mandatory quantity reporting also applies to postings in the relevant categories.

projekte

Projects and initiatives

As part of our commitment to circularity, STRABAG focuses not only on its in-house implementation concepts for recycling, but also on strategic partnerships.

Building resource passport

One of these partners is Concular. STRABAG has been working with the Berlin start-up since 2022 to develop a circular building resource passport. Enabling circular construction and keeping the raw materials used in the cycle at a high level of quality and for as long as possible requires information: Which resources and materials are used, in what quantity and quality, at what point in the building process, and in what way? The aim of the digital resource passport for buildings is to fulfil this information-gathering function. That makes it a central building block for a functioning circular economy. Concular is a market leader for material passports and the reintroduction of materials. STRABAG contributes the necessary construction industry expertise.

Circular deconstruction

In addition to the building resource passport, STRABAG is also making use of Concular’s solutions for the circular deconstruction of buildings. At the ZÜBLIN campus in Stuttgart, for example, the refurbishment of the Group’s Z2 building – represented by the technology experts from STRABAG BRVZ – offers a wide range of potential for collaboration. Following an assessment, evaluation and digital documentation of the existing material, a total of over 350 materials from Z2 were expertly removed, made available for further use by Concular and reintroduced into the cycle. Modular partition walls and fire doors, for example, have already found new uses in Europe’s largest makerspace and in the Kulturhaus Chemnitz cultural centre.

Esslingen district government office

The new Esslingen District Government Office shows how circular planning and design can be applied to all phases of a building’s life cycle. Before the project got started, a so-called material flow balance sheet was drawn up as the basis for a waste concept prioritising high-quality recycling and short transport paths. Through selective deconstruction and waste sorting, more than 90% of the materials recovered from the old building can be kept in the cycle and reused. The approximately 31,500 tonnes of concrete waste are crushed and screened directly on site for reuse as aggregate in resource-saving concrete (R concrete). These building materials containing a high percentage of secondary raw materials are later used in the construction of the new building, while cradle-to-cradle certified products are used in the fit-out. During operation, the building adapts to different requirements thanks to a flexible, modular space concept. Even the end of the building’s service life was taken into account during planning: A catalogue of ecologically sound building components and a special demolition concept are being drawn up for the new administration building. In the event of the building’s future deconstruction, the materials that were used can be easily located, separated and sorted.

Outlook

Strategy 2030 aims to minimise the wastage of raw materials and to reduce negative environmental impacts. Several working groups have been established for the strategic action areas of reconstruction, conversion and refurbishment, sustainable building materials and value stream management. The flow of information between the various initiatives is ensured by the corporate sustainability network and Group-wide project teams.

The working group on value stream management has been tasked with the collection of material and waste data, among other things. A standardised system for recording waste data developed during the 2023 financial year will be applied across the Group starting in 2024. The first step is to improve the data basis. In a next step, this data should help us to better manage our recyclable materials and anchor the principle of circularity even more firmly at STRABAG.

Sources – Chapter: Circularity

Circle Economy, 2023: The Circularity Gap Report 2023, accessed on 25 January 2024

bsve (Bundesverband Sekundärrohstoffe und Entsorgung e. V.), 2020: Statusbericht der deutschen Kreislaufwirtschaft [Status Report on the German Circular Economy], accessed on 25 January 2024