The thermostat of opportunity: Home air conditioning, its social gradient, and educational consequences

Rising global temperatures pose a significant threat to student cognitive functioning, positioning access to air conditioning (AC) as a critical adaptation mechanism. However, the unequal distribution of this resource threatens to establish a new line of educational inequality. While research has focused on school-based cooling, the home environment remains a critically understudied channel for heat-related learning losses, despite being the primary setting for independent study and sleep. To investigate the prevalence, social stratification, and academic implications of home AC access, we analyze data from the Programme for International Student Assessment spanning 2006-2022. The dataset comprises 576,786 fifteen-year-old students across 21 countries and five continents. Our cross-national analysis reveals that while residential AC is diffusing globally, access remains strongly stratified by socioeconomic status. Consistent with the theory of Maximally Maintained Inequality, these socioeconomic gaps only begin to diminish in nations approaching market saturation. Furthermore, we identify a context-dependent relationship between home AC and academic achievement. In hotter climates, students with residential AC achieve higher test scores than those without, even after adjusting for socioeconomic covariates. This finding supports a heat-mitigation mechanism, suggesting that residential AC provides a protective shielding effect. Conversely, in cooler contexts, associations are negligible or negative. We conclude that as the climate crisis intensifies, the home learning environment must be recognized as a material determinant of educational equity and a key site for climate adaptation policy.