For years already, European research and innovation policy revolves around a deceptively simple question: “What is its TRL?” Whether developing a next‑generation battery, a mobility service, or a digital platform, Technology Readiness Levels (TRLs) have become the standard shorthand for describing how mature a technology is. Horizon 2020 and Horizon Europe embedded TRLs deeply into work programmes, call texts, and evaluation criteria, making them one of the most recognisable metrics in the EU’s innovation landscape.

As the EU continues to push for faster deployment of clean, digital, and resilient technologies, understanding TRL (and using it correctly) remains essential.

What Is TRL?

TRL stands for Technology Readiness Level, a nine‑step scale originally developed in the aerospace and defence sectors. It measures how far a technology has progressed from an initial idea to a fully validated solution operating in real‑world conditions.

The scale is now standardised by NASA, ESA, and widely used across the European Commission. Check for instance this good reference document (Euraxess).

How TRL Works

TRL tracks technical maturity, not market readiness, societal acceptance, or business viability. Each level answers a specific question about the technology’s development stage:

• TRL 1–3: Has the basic principle been observed? Has it been validated in the lab?
• TRL 4–6: Has it been tested in a relevant environment?
• TRL 7–9: Can it operate reliably in real operational conditions?

A high TRL means the technology works as intended in its target environment — a critical requirement for many EU funding instruments.

Why TRL Matters in EU Funding

TRL is often used as a numeric condition in Horizon Europe calls. For example:

• “Activities are expected to start at TRL 3 and reach TRL 5 by the end of the project.”
• “Demonstration actions must achieve TRL 7.”

This clarity helps applicants understand expectations and helps evaluators assess whether a project is realistically scoped.

TRL also plays a role in:

• structuring work packages
• defining milestones
• planning demonstration activities
• aligning industrial and research partners

Because TRL is widely understood across sectors, it provides a common language for consortia that mix universities, SMEs, industry, and public authorities.

How TRL Is Used in Practice

While TRL is simple in concept, applying it correctly requires careful planning. Projects must demonstrate:

• evidence of validation or demonstration
• appropriate testing environments
• clear progression from one TRL to the next
• alignment between objectives, resources, and expected TRL outcomes

For example, moving from TRL 5 to TRL 6 typically requires testing in a relevant operational environment, and not just improved lab results.

If you want a handy help for the self-assessment, we recommend that you take a look at this self-assessment tool from the BRIDGE2HE project.

Where TRL Is Most Relevant

TRL is especially important in areas where technical performance is the primary barrier to deployment, such as:

• clean energy technologies
• advanced manufacturing
• aerospace and defence
• digital infrastructure
• mobility systems

In these fields, demonstrating technical reliability is essential before addressing regulatory, societal, or market challenges.

Societal Readiness Levels (SRL)

Beyond technical maturity, the European Commission has recently begun emphasising Societal Readiness Levels (SRL) as a complementary lens for evaluating innovation. While TRL focuses on whether a technology works in its intended environment, SRL assesses how well a solution is adapted to and accepted by society. The concept mirrors the nine‑level TRL scale but shifts attention to stakeholder involvement, societal concerns, institutional fit, and the broader context needed for real‑world uptake. A project can therefore be technically mature (e.g., TRL 9) yet societally unprepared (e.g., SRL 1), highlighting a gap that often explains why promising innovations fail to achieve adoption.

The European Commission is now piloting SRL in Horizon Europe, where selected topics (e.g. in Cluster 5) require applicants to integrate societal readiness activities throughout their work plans. This includes allocating resources, involving SSH (social sciences and humanities) partners, addressing societal concerns, and producing dedicated SRL reports. The pilot aims to determine whether SRL should be expanded to other clusters, especially in areas where societal resistance or behavioural factors are known barriers to deployment. As such, SRL is emerging not as a replacement for TRL, but as a complementary metric that helps ensure innovations are not only technically sound but also socially viable. Check this introductory article on SRL if you want more details.

Conclusion

TRLs continue to be the central metric for evaluating the technical maturity of innovations in Europe. Their simplicity, clarity, and widespread adoption make them indispensable for researchers, innovators, and policymakers.

At the same time, the introduction of Societal Readiness Levels (SRL) adds an important new dimension by assessing whether innovations are developed with societal needs, concerns, and contexts in mind. It is to be expected that future innovation frameworks may rely on both TRL and SRL to ensure that solutions are not only technologically robust but also ready for real‑world acceptance and uptake.