Measuring Sustainability in Economic Output in the Member States that Joined the European Union in 2004

• Resource productivity (RP) is a frequently used measure of sustainability. • RP is the ratio of GDP to domestic material consumption (DMC). • RP is examined in the member states of the European Union between 2011 and 2021. • Based on the results, RP has an impact on GDP. • The RP is influenced by different factors in the member states that joined in 2004. The 2004 enlargement of the European Union (EU) marked a significant shift, integrating ten new member states, most of which had experienced economic lag due to their historical background. This study assesses the progress of these countries in closing the gap with older EU members from 2011 to 2021, focusing on resource productivity as a key indicator of sustainable economic growth. Using panel regression and structural equation modeling, the analysis highlights persistent differences between the EU-27 and EU-10. Findings suggest that in EU-27 countries, resource productivity is driven primarily by circular economy measures, waste recycling, and renewable energy utilization. In contrast, EU-10 countries, still undergoing economic transformation, rely more on innovation, human capital development, and research and development (R&D) investments to enhance efficiency. Notably, while renewable energy positively impacts resource productivity in EU-27, it shows a paradoxical negative effect in EU-10, likely due to transitional inefficiencies. Fixed effects models confirm that institutional, political, and infrastructural differences shape resource productivity. The results underscore that while the EU-10 has significantly improved, gaps remain in areas such as higher education investment and circular material use. Importantly, research and development emerge as critical drivers of efficiency, especially in EU-10. The study concludes that while economic modernization fosters convergence, sustainability strategies must be tailored to regional contexts. Strengthening innovation systems and optimizing material efficiency are essential for long-term resource productivity gains.