Unpacking energy vulnerability in the European Union: Linking thermal discomfort with adaptive capacity

Energy poverty remains a pressing challenge across the European Union, shaped by structural, socioeconomic, and behavioural factors. As climate change intensifies, it is essential not only to reduce existing energy poverty but also to prevent households from becoming vulnerable to it. Current assessments often rely on narrow technical measures, overlooking how building inefficiencies interact with households' ability to adapt to thermal discomfort. This study proposes a multidimensional Energy Vulnerability Index, using harmonised and publicly available data. The index integrates two dimensions: a building energy performance gap index, reflecting exposure to thermal discomfort, and an adaptive capacity index, which combines socioeconomic and behavioural factors. Behavioural dimensions such as digital literacy and perceived self-efficacy capture aspects of adaptive capacity rarely operationalised at regional scale. Applying the index across Europe's macro regions reveals substantial spatial variation: regions with similar levels of building performance can still experience high energy vulnerability when socioeconomic and behavioural capacities to adapt to thermal discomfort are weak. We further show that the interaction between these factors varies across rural and urban contexts. These findings highlight the limitations of relying solely on technical performance metrics to assess energy vulnerability. Our framework provides policymakers with a practical tool for identifying action priorities and designing interventions that are targeted to regional conditions, strengthening both structural efficiency and households' adaptive capacity in the face of climate change.