Climate change mitigation necessitates a shift towards low-carbon energy systems, emphasizing human and societal considerations. While the need for Social Sciences and Humanities (SSH) research in this area is widely acknowledged, two key gaps exist. First, SSH input is often narrowly focused and used instrumentally to support pre-determined policy initiatives, often in a subordinate role to technical sciences. Second, SSH researchers are rarely involved in setting research agendas, leading to an incomplete and potentially biased perspective. This paper addresses these gaps by presenting a collectively elaborated research agenda for future SSH research on energy efficiency, developed through a Horizon Scanning exercise.

The paper reviews the historical evolution of SSH research on energy efficiency, starting from early commentaries on technological progress and energy demand in the late 1800s to the shifts caused by the oil crises of the 1970s. It highlights the transition from focusing on energy security to addressing climate change, the development of research on human behavior related to energy use, and the more recent critical perspectives that question energy efficiency as an unequivocal goal, favoring sufficiency. The literature review also notes the increased focus on energy justice and intersectional studies, highlighting the uneven distribution of energy efficiency's impacts.

A Horizon Scanning exercise was conducted, inspired by similar exercises in other fields. A Steering Committee (the first four authors) oversaw the process, supported by a Working Group (the remaining authors) that broadened input from their research communities. The Working Group members were carefully selected to represent a wide range of SSH disciplines, countries, career stages, and genders. They solicited research questions from their networks via an online survey, resulting in 513 initial questions. These questions were rigorously edited and refined, eliminating irrelevant or poorly formulated questions. Then, a structured evaluation process involving scoring and two deliberation workshops was implemented to arrive at a final list of 100 priority SSH research questions.

The 100 priority research questions were inductively clustered into seven themes: Theme 1: Citizenship, engagement, and knowledge exchange in relation to energy efficiency. This theme explores how to democratize energy efficiency measures and foster meaningful citizen participation, emphasizing community-based initiatives and diverse forms of social learning. Theme 2: Energy efficiency in relation to equity, justice, poverty, and vulnerability. This theme focuses on the distributional impacts of energy efficiency policies, advocating for social justice approaches that address inequalities and vulnerabilities, including energy poverty. Theme 3: Energy efficiency in relation to everyday life and practices of energy consumption and production. This theme examines how energy efficiency intersects with people's everyday lives, practices, and the sociotechnical systems that shape them, moving beyond individualistic models of behavior. Theme 4: Framing, defining, and measuring energy efficiency. This theme addresses fundamental issues of defining, modeling, understanding, and measuring energy efficiency, emphasizing the social and political influences on these processes and exploring alternative framings like energy sufficiency. Theme 5: Governance, policy, and political issues around energy efficiency. This theme investigates the governance and policy aspects of energy efficiency, examining the power dynamics, institutional challenges, and the integration of energy efficiency with other policy areas, including energy sufficiency. Theme 6: Roles of economic systems, supply chains, and financial mechanisms in improving energy efficiency. This theme focuses on how economic systems, financial mechanisms, and supply chains influence energy efficiency, considering both Global North and Global South perspectives and the implementation gap between legislation and practice. Theme 7: The interactions, unintended consequences, and rebound effects of energy efficiency interventions. This theme explores the complex interactions and unintended consequences of energy efficiency interventions, considering rebound effects, intersections with other policy areas, and the role of invisible energy policies.

The 100 research questions generated challenge the mainstream paradigm of energy efficiency research and policy, which often focuses on technological substitution and individual behavior modification. The agenda highlights the importance of interconnectedness, complexity, and systemic approaches, moving beyond simplistic dichotomies and recognizing the co-evolution of demand and supply. It emphasizes the need for inclusive and participatory approaches, challenging top-down, techno-centric models, and promotes the concept of ‘social innovation’ as a key driver of energy transitions. The findings demonstrate the potential of SSH research to significantly contribute to more effective and equitable energy efficiency policies and practices.

This paper provides a valuable research agenda for future SSH work on energy efficiency, highlighting 100 priority research questions across seven key themes. The inclusive and deliberative methodology used showcases the benefits of collaborative agenda-setting within the SSH field. The findings challenge prevailing paradigms and underscore the need for systemic, participatory, and justice-oriented approaches to achieve energy efficiency goals. Future research should focus on addressing the identified gaps, particularly expanding research in Global South contexts.

The geographic scope of the Horizon Scanning exercise is limited to EU and associated countries, which may restrict the generalizability of the findings to other contexts, especially the Global South. The selection of participants, while aiming for inclusivity, inevitably reflects the views and perspectives of the involved researchers, and a different participant pool could yield a different set of questions. The timing of the study may also influence the priorities identified, reflecting the specific concerns and policy contexts at that time.