Approximately one in two homes in France do not provide adequate protection against extreme heat [1].

This vulnerability creates a critical public health risk during heatwaves, as poorly insulated housing traps heat and increases the likelihood of heat-related illnesses. The crisis is most acute in lower-income areas and aging suburban developments where residents lack the means to modify their living environments.

Manuel Domergue, the director of studies for the Fondation pour le logement, said that "un logement sur deux ne protège pas des fortes chaleurs" [2]. This phenomenon, often referred to as "logements-bouilloires" or kettle homes, occurs when buildings absorb and retain heat without providing a way to cool the interior [1].

Domergue said that the situation is not improving. He said that "les indicateurs se dégradent chaque année" [1]. The degradation is driven by an aging national housing stock and a growing trend of summer energy precariousness, where residents cannot afford or access the tools necessary to maintain safe indoor temperatures.

According to the Fondation pour le logement, the burden of this heat is not distributed evenly across the population. Domergue said that "les quartiers populaires sont surexposés à la précarité énergétique d'été" [3]. These high-density, working-class neighborhoods often feature older construction materials that lack modern thermal insulation, making them more susceptible to the rising temperatures seen during the current June heatwave.

While winter energy poverty has historically been the primary focus of French housing policy, the rise of the "kettle home" shifts the urgency toward summer mitigation. The study highlights that the combination of urban heat islands and inadequate housing creates a compounding effect for the most vulnerable populations [3].

“"Un logement sur deux ne protège pas des fortes chaleurs."”

The prevalence of 'kettle homes' signals a shift in climate adaptation needs in France. While energy policy has traditionally focused on heating costs during winter, the systemic failure of housing to protect against heat suggests that urban planning and building codes must now prioritize thermal cooling to prevent mass casualty events during increasingly frequent summer heatwaves.