Low-Carbon Concrete in German Tenders 2026

Methodology

A recent target audience simulation by Minds shows that 72 percent of German structural engineers have significant concerns about using low-carbon concrete in public tenders if it extends curing times. Validated using data from the Statistisches Bundesamt, the study highlights how deeply DIN standards and liability risks are anchored in the conservative German construction sector.

The Conflict Between Decarbonization and Construction Schedules

Reducing the carbon footprint in the construction sector is one of the most urgent challenges of our time. Since cement production accounts for a significant share of global greenhouse gas emissions, the development of climate-friendly alternatives is a core focus of the building materials industry. A promising lever is the use of low-clinker cements, such as blast furnace cements (CEM III/A or CEM III/B), where a large portion of the carbon-intensive Portland cement clinker is replaced with ground granulated blast-furnace slag. This substitution can reduce concrete's carbon emissions by over 50 percent, as confirmed by studies from the Fachhochschule Kiel and EKSH.

However, the decisive disadvantage of these ecologically beneficial materials lies in their hydration kinetics. Low-clinker cements exhibit significantly slower early strength development. While classic concrete with Portland cement (CEM I) achieves high strength after just a few days, concrete with a high slag content takes significantly longer to reach the minimum compressive strength required for stripping formwork. In modern building construction, which is characterized by extremely tight schedules and minimal retention times for formwork systems, any delay in stripping leads to massive logistical and financial consequences.

The Minds simulation illustrates that the time factor on the construction site often negates the ecological benefits in practice. If formwork has to remain in place longer, rental costs for the formwork material rise, and the entire construction process is delayed. For construction companies and project developers, these unpredictable delays represent a high financial risk, which they ultimately pass back to the structural engineers.

DIN Standards and German Risk Aversion

Internationally, the German construction sector is considered one of the most conservative and heavily regulated markets. Structural design is based on a dense network of standards, particularly DIN 1045-2 for concrete and Eurocode 2 (DIN EN 1992). These regulations are primarily designed for maximum safety and durability. New, greenhouse gas-reduced concretes must fight their way through tedious approval processes before they can be used in standard building construction. Although the guideline of the Deutscher Ausschuss für Stahlbeton (DAfStb) on carbon reduction in load-bearing structures attempts to create a regulatory framework, skepticism among engineers remains high.

In Germany, structural engineers bear personal, civil, and criminal liability for the structural stability of the buildings they calculate. This liability leads to a pronounced risk aversion. If an innovative building material is used that is not fully covered by classic DIN standards, or whose long-term behavior (such as carbonation and chloride resistance) is less documented, planners will, when in doubt, default to proven, clinker-intensive standard mixes.

The Minds simulation shows that only 31 percent of the surveyed structural engineers would be willing to adjust safety factors in structural calculations to facilitate the use of eco-concrete. This highlights that the regulatory framework and personal liability risk are the biggest bottlenecks for the decarbonization of concrete construction. As long as standards do not provide clear liability relief for using sustainable materials, technological change remains blocked.

The Role of Tenders and Liability Issues

Public tenders play a key role in the market introduction of sustainable building materials. As the largest client, the public sector has a duty to lead by example and establish green public procurement criteria. Guidelines such as the Allgemeine Verwaltungsvorschrift zur Beschaffung klimafreundlicher Leistungen (AVV Klima) explicitly demand that the carbon footprint be considered over the entire life cycle of a building in accordance with DIN EN 15643.

In practice, however, these ambitious requirements clash with the reality of German procurement law and construction contract practices. Public tenders are usually extremely price- and schedule-sensitive. Although 64 percent of structural engineers in our Minds simulation support the introduction of binding carbon classes in tenders, in actual projects, these requirements collide with contractually agreed completion dates.

If a structural engineer specifies a carbon-optimized concrete in the tender that delays construction progress due to slower hardening, the client faces high contractual penalties from future users or operators. Furthermore, since procurement law usually favors the most economical bidder, innovative building materials that are more expensive to purchase or process are often left behind. There is a lack of a holistic evaluation that realistically factors in the shadow price of carbon and life-cycle costs.

Minds Three-Stage Model for Validating B2B Decisions

To precisely map the complex decision-making processes and deep-seated reservations of a highly specialized target audience like German structural engineers, Minds uses a scientifically grounded three-stage model. This model ensures that the simulation results are not based on mere assumptions, but accurately reflect real market dynamics.

First, data anchoring (Level 01): Every simulation is calibrated using real market data, CRM systems, internal studies, or traditional market research. For this study, real data on tendering procedures, technical data sheets from cement manufacturers, and surveys among German engineers were used as the foundation.

Second, the simulation model (Level 02): At this level, demographic and psychographic behavioral patterns are modeled. The model takes into account the specific risk aversion of German engineers, their legal framework (professional liability, VOB/B), and their professional training.

Third, validation (Level 03): The results are continuously benchmarked against real reference data and official statistics. This includes data from the Statistisches Bundesamt on the structure of the main construction industry, Eurostat data on material efficiency, and established market studies from institutes like Kantar. Through this three-stage validation, Minds achieves an average alignment of 85% to 95% with traditional, physical panels.

A decisive advantage of this methodology is speed and efficiency. While a traditional B2B panel survey among structural engineers takes several weeks or months and is associated with extremely high recruitment costs, Minds delivers these deep insights in under an hour. This is done at a fraction of the cost of a traditional panel and without the need to painstakingly recruit individual experts. Furthermore, the entire simulation takes place on servers within the European Union and is therefore 100% GDPR-compliant, as no personal data of real participants is processed.

Strategic Implications for Building Material Manufacturers

For manufacturers of low-carbon concrete and innovative binders, this Minds simulation provides valuable insights for sales and marketing strategies in the middle of the buyer journey (mofu). To convince structural engineers of new products, it is not enough to simply advertise carbon savings. Manufacturers must actively address the technical and legal pain points of planners.

This includes providing detailed design aids that minimize the impact of longer curing times on the construction process, for example through optimized formwork concepts or the targeted use of safe hardening accelerators. In addition, manufacturers must proactively minimize liability risks by providing comprehensive certifications, national technical approvals (abZ), and transparent environmental product declarations (EPDs). Only when structural engineers have the certainty that they are operating within a safe regulatory framework and that the construction schedule is not at risk will they be willing to specify the green building material of the future in their projects.

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