CC BY 4.0Yu, SongminSongminYuMandel, TimTimMandelThomas, StefanStefanThomasBrugger, HeikeHeikeBrugger2022-08-162022-08-162022https://publica.fraunhofer.de/handle/publica/41981210.1007/s12053-022-10049-6Energy Efficiency First (EEF) is an established principle for European Union (EU) energy policy design. It highlights the exploitation of demand-side resources and prioritizes cost-effective options from the demand-side over other options from a societal cost-benefit perspective. However, the involvement of multiple decision-makers makes it difficult to implement. Therefore, we propose a flexible decision-tree framework for applying the EEF principle based on a review of relevant areas and examples. In summary, this paper contributes to applying the EEF principle by defining and distinguishing different types of cases - (1) policy-making, and (2) system planning and investment - identifying the most common elements, and proposing a decision-tree framework that can be flexibly constructed based on the elements for different cases. Finally, we exemplify the application of this framework with two example cases: (1) planning for demand-response in the power sector, and (2) planning for a district heating system.enEnergy Efficiency First principleDecision-tree frameworkDemand-response planningDistrict heatingjournal article