Special issue “Energy system effects of the Energy Efficiency First Principle” (Editorial)

The “Energy Efficiency First Principle” (EE1st), also referred to as "Efficiency First," constitutes a foundational tenet increasingly embedded within policymaking, strategic planning, and investment decision-making in the energy sector, gaining prominence particularly within European energy and climate policy frameworks. This Special Issue comprises eight scholarly articles that investigate the systemic impacts of the Energy Efficiency First Principle through five analytical lenses: (i) individual and behavioral; (ii) local and urban; (iii) dynamic; (iv) sector-coupling; and (v) comprehensive energy system perspectives. A unifying feature across these contributions is the advancement and application of novel methodological approaches, including sophisticated spatial and temporal modeling techniques and integrated energy system modeling frameworks, which collectively facilitate a rigorous and quantitative assessment of the multifaceted dimensions of the Energy Efficiency First Principle and its implications for energy system transformation.