Societal acceptance and Energy Efficiency in EU Energy Systems: Governance Regimes of Trust and Regulatory Quality

Societal acceptance is increasingly recognised as a binding constraint on energy efficiency in the European Union, where permitting delays, contested projects, and local resistance keep infrastructure from being deployed and operated at technically achievable efficiency levels. This chapter argues that acceptance is not a uniform function of institutional quality but an implementation outcome jointly shaped by institutional trust and regulatory quality, and that this relationship is conditioned by the broader governance configuration in which a country operates. Using panel data for EU Member States over 2014–2022, the study combines system-level institutional trust (European Social Survey), regulatory quality (Worldwide Governance Indicators), and implementation-related indicators of acceptance such as renewable deployment, permitting performance, and project progression. Member States are grouped into three governance regimes through k-means clustering, and regime-based interaction and panel models estimate how trust and regulatory quality translate into acceptance within each regime. The results reveal a non-linear, configuration-dependent pattern rather than a simple governance gradient. Institutional trust emerges as a meaningful driver of acceptance only in an intermediate "transition" regime; in the highest-capacity regime its marginal effect flattens, consistent with institutional saturation, while in the most constrained regime weak institutional conditions suppress acceptance regardless of trust. Regulatory quality shows no stable independent effect, operating instead as a background condition. These patterns hold under cluster-robust inference, leave-one-country-out tests, and alternative cluster counts. The findings imply that uniform governance prescriptions are unlikely to succeed across the EU: raising acceptance requires interventions matched to each regime's structural position.