Comparative assessment of energy-related environmental impact management systems and decarbonisation policies in energy transitions

This study presents a comparative assessment of energy sustainability potential using the Integral Sustainability Potential Index (ISPI), which integrates four indicators: energy intensity (EI), the share of renewable energy sources (RES) in electricity generation, the diffusion of ISO 50001-certified energy management systems (EnMS), and political readiness. The methodology is applied to Central and Eastern European countries (Poland, Romania, Bulgaria, Slovakia, and Ukraine). The results reveal substantial cross-country differences in sustainability potential, primarily driven by institutional capacity, policy coherence, and the scale of ISO 50001 implementation. Poland demonstrated the highest ISPI value (0.68), reflecting moderate EI, a relatively high RES share, widespread adoption of ISO 50001 in the industry, and strong political support for EnMS. Romania (ISPI = 0.56), Bulgaria (ISPI = 0.39), and Slovakia (ISPI = 0.37) exhibit a medium level of sustainability potential, supported by notable RES penetration and policy initiatives but constrained by the limited diffusion of ISO 50001. Ukraine shows a significantly lower ISPI value (0.32), which is associated with high-EI (≈ 2.68 toe/1000 €), a lower RES share, weak implementation of ISO 50001, and insufficient policy support for EnMS. Cross-country analysis reveals a consistent pattern: countries with the lowest ISPI values (0.32–0.37) have the highest EI (>95 kilogrammes of oil equivalent/1000 €) and the lowest ISO 50001 certification density (<10 per million populations), while the country with the highest ISPI (0.68) combines moderate EI with the highest certification density. Overall, the findings indicate that economies with more developed managerial and policy frameworks have higher sustainability potential despite structural challenges in the energy sector.