A global, proxy-based assessment of building climatization vulnerability.

Building compactness and construction epoch are relevant proxies of energy efficiency in buildings. By integrating building stock and Earth observation data, we characterize buildings globally and identify vulnerable areas dominated by old building age and unsuitable compactness in relation to climate conditions. Such areas are home to a population of 48 million persons that could increase by 10% to 30% by 2100 under likely socioeconomic pathways, shifting from cold regions of Eurasia to the heat-prone Sahel zone, Gulf countries and Pakistan. Results reveal stark disparities in building energy efficiency across income levels, urbanization patterns, and climate zones. Almost half of buildings globally (i.e., 43%) were built before 1980, when few to no energy efficiency measures existed, and these buildings are concentrated mainly in temperate and cold-climate urban areas in high-income countries. Low-income countries experienced more recent, lightweight and less compact urban expansion, which exposes them to the forecasted climate warming: this could increase their energy demand, hinder climate adaptation and imposes further challenges to ensure affordable thermal comfort for all.