Physical and Social Vulnerability to Heat Waves in Rural Communities with Vernacular Architecture: Villages in the Montesinho Natural Park (Portugal) as a Case Study

Vernacular architecture in depopulating rural areas faces critical challenges due to climate change, particularly with the rise in extreme events like heat waves. These events threaten the conservation of buildings and the well-being of their inhabitants, especially in regions undergoing demographic decline and an aging population. The sustainability of these structures, built with traditional materials and techniques, raises important questions about their ability to withstand current and future conditions especially in dry and warm climates. This study explores the combined physical and social vulnerability of vernacular buildings exposed to heat waves, focusing on how architectural and sociodemographic factors influence the resilience of these structures and their inhabitants. Using a vulnerability index-based methodology and an on-site data collection, vulnerability levels across a variety of vernacular buildings and vulnerable households have been identified. The results emphasize how passive design features can help to mitigate the effects of extreme heat. At the same time, social factors worsen vulnerability, particularly for aging and low-income populations—common characteristics of many depopulating rural areas. This research underscores the importance of protecting the cultural and functional value of vernacular architecture, positioning it not only as a component of rural identity but also as a critical resource for climate adaptation.