Green Efficiency and Productivity Change in Wood Waste Utilization Across EU Countries: A Directional Distance Function Approach

Abstract

Efficient wood waste utilization supports the circular bioeconomy, but comparative evidence on national treatment systems remains limited. This study benchmarks 21 EU member states using radial and non-radial directional distance functions (DDFs), distinguishing pathway-specific adjustment potential. Eurostat data cover seven biennial reporting years from 2010 to 2022 (147 observations). Domestic wood waste generation is the input; material and energy recovery are desirable outputs; landfilling and incineration without energy recovery constitute the undesirable output. Productivity is assessed using a radial Global Malmquist–Luenberger index and an additive non-radial Luenberger indicator. Poland, Germany and France are closest to the non-radial frontier. Spain and Portugal show the largest baseline non-radial scores, dominated by proportional energy-recovery adjustments. Input adjustments are zero in the estimated solutions, but this does not establish independence from waste volume; across the 21 country averages, the association is negative and borderline non-significant at the 5% level (Spearman ρ = −0.43, p = 0.051); the observation-level association (ρ = −0.27, p = 0.001; n = 147) is not independent because it involves repeated observations within countries. Rankings remain similar under an aggregate treatment-volume cap (ρ = 0.96). A generation-normalized direction removes the extreme values and shifts the dominant adjustment towards material recovery. Results identify specification-dependent benchmark gaps rather than physically attainable targets or causal policy prescriptions, supporting pathway-specific monitoring alongside assessments of waste quality and environmental impacts.