Does the European Green Deal Reach Microenterprises? Repeated Cross-Sectional Evidence on Resource Efficiency Adoption and Firm-Size Convergence Among EU SMEs

Small and medium-sized enterprises (SMEs) represent the majority of EU businesses and a disproportionate share of its environmental impact, yet longitudinal evidence on their resource efficiency behaviour remains scarce. This study examines whether SME adoption of resource efficiency practices increased between 2017 and 2024 and whether the size gradient changed across a period spanning several major and concurrent institutional and economic events: the European Green Deal (2019), the Circular Economy Action Plan (2020), the COVID-19 pandemic and its economic aftermath (2020–2021), the energy price shock that intensified in 2021 and was amplified by the Russia–Ukraine conflict in 2022, and the early implementation phase of the Corporate Sustainability Reporting Directive (2022–2024). These events overlapped substantially in time and cannot be disentangled with the present empirical design. Using microdata from three Flash Eurobarometer waves (N = 38,165; EU27), we construct a harmonised eight-item adoption index and estimate a weighted Poisson regression with cluster-robust standard errors and wave × firm-size interactions. Adoption increased substantially: SMEs reporting no resource efficiency action fell from 10.5% to 4.2%, and renewable energy use more than doubled (+15.3 pp). More substantively, the population-level gap in resource efficiency adoption between medium-sized enterprises (50–249 employees) and microenterprises (1–9 employees) narrowed by 81%, from +0.89 practices in 2017 (out of a maximum of 8) to a statistically non-significant +0.13 and +0.17 practices in 2021 and 2024 respectively (interaction IRR ≈ 0.81–0.82, p < 0.001 in both waves), robust to nine checks. The size gradient in environmental behaviour appears not to be structural but a dynamic feature of the institutional landscape, one that narrowed substantially over a period coinciding with intensifying regulatory ambition and energy price shock—though the present repeated cross-sectional design cannot establish which mechanisms drove this compression.