Dispersed settlement patterns can hinder the net-zero transition : evidence from Ireland

Limiting the growth of final energy demand helps meet the steep greenhouse gas (GHG) reduction trajectories required to address climate change, and can also bring wider sustainability benefits. Integrated Assessment Modelling (IAM) and energy systems modelling analyses are increasingly including low energy demand (LED) measures in GHG mitigation scenarios, but their granularity and empirical basis is typically low, limiting actionable insights. Here, we contribute to addressing this gap by examining the role of spatial settlement patterns as a driver of energy service demand, particularly in the transport and residential sectors. We focus on Ireland, which has enacted ambitious decarbonisation commitments in law, that are challenging to deliver partially due to a large proportion of the population living in rural one-off housing. We perform exploratory data analysis to estimate the mathematical relationship between various energy service demands and the dispersal of population, and calculate the energy service demand level and CO2 emissions per capita at various population densities. We also review the indirect impact spatial settlement patterns have on climate mitigation, via the viability of enabling low-carbon infrastructure. We find that higher density settlement patterns are associated with lower energy service demands and greater potential for infrastructure to enable the low carbon transition. We also find that residential and transport GHG emissions are, respectively, 62% and 52% lower for populations living in the highest density regions than in the lowest. Finally, we discuss a path forward for incorporating this empirical analysis into future mitigation scenarios.