Impact of changes in the distribution of household types on residential energy consumption in Spain, 2006–2023

• Demographic shifts, like aging and smaller households, increase energy use • New method merges survey and census data to assess household effects on energy. • Regional disparities in energy use exist, with the Mediterranean more affected. • Solutions are needed, like efficient housing, co-housing, and behavioral changes. • Findings offer insights for aging societies to integrate demographics into policy. Residential energy consumption remains difficult to analyze due to its heterogeneity and evolving demographic trends, as factors such as population aging and declining household sizes alter energy demand and may offset efficiency gains. However, most studies fail to disaggregate energy use by household type over time, creating a gap in understanding the demographic impact on residential energy demand. This study addresses this gap by analyzing Spain, integrating demographic data from the Population and Housing Census with micro-level household energy consumption data from the Household Budget Survey (2006–2023). Using the Integrated Analysis of Demographic and Consumption Profile (IADCP) method, we quantify the effects of changes in household composition on energy demand, isolating the influence of technological advancements, population growth, and shifts in household composition. The findings reveal that while technological progress, economic factors, and behavioral changes have led to significant efficiency gains, demographic changes have offset these benefits, resulting in an energy efficiency loss of 10.07% due to changes in population dynamics, split in 6.78% due to the increase in the number of households, and 3.30% due to household composition shifts. Looking for causes, the increase in the number of households has a more pronounced effect in the Mediterranean region, whereas smaller and older households exert a greater influence in the North Atlantic region. This research highlights the need to integrate demographic factors into energy policy and advocates energy-efficient housing, co-housing models, and behavioral interventions to mitigate the negative impacts of demographic changes on residential energy demand.