Faced with more intense, frequent and longer heat waves, “more and more people are faced with the unsuitability, or even uninhabitability, of their homes for several months of the year,” the authors point out. With sometimes fatal consequences, the number of heat-related deaths in summer 2023 is estimated at 5,000, including 75% among those aged 75 and over. The cause in particular is the poorly insulated walls and the poorly ventilated housing, but also the absence of exterior spaces or shutters.
“Beyond the euphemism of summer comfort is the livability of homes and their ability to protect their residents. […] which we urgently need to take into account”, warns Christophe Robert, general delegate of the FAP. Despite some developments, adapting homes to heat “is not yet at the heart of renovation policies”, the report continues.
Moreover, the fight against energy poverty is mainly focused on reducing energy consumption, decarbonizing heating and maintaining a minimum temperature in homes. Also, regulatory or heritage constraints sometimes prevent the installation of solar protection or the application of light colors on the facade and roof.
93% of the park exposed
The situation is all the more critical as it risks getting worse. “One in seven French people lives in an area that will be exposed to more than twenty abnormally hot days every summer by 2050,” the report warns. Worse, with the prospect of 4°C warming, 93% of the built stock will be exposed “to a strong or very high risk of heatwaves”. According to an Ipsos-RTE survey published in May 2023, 37% of respondents suffer “both hot and cold”, in homes that are impossible to heat in winter and turned into kettles in summer.
Apartments are also “three times more likely to overheat than detached houses”. More mineral, denser and often devoid of vegetation, the morphology of cities “intensifies the feeling and consequences of heat waves, by participating in the urban heat island (UHI) phenomenon”.
These UTIs related to concrete that stores heat during the day and retransmits it at night, but also to car traffic, generated a temperature difference of 10°C between the city and the countryside during the great heat wave of 2003. According to a study published in May in Lancet Planet HealthParis is the capital of Europe where the risk of mortality due to heat waves is the highest due to the density and lack of green spaces.
No public aid is planned
Under-25s, who are more likely to live in small, poorly insulated houses, suffer from the heat in the summer at a rate of 71%, as do 70% of renters, according to the Ipsos/RTE survey. Single mothers, the elderly, who are more physiologically vulnerable, and low-income households are also more affected.
Despite this worrying observation, no specific public aid is planned to adapt housing to heat waves, apart from large-scale renovations, the authors note. “It would have been useful to subsidize simple actions for millions of households exposed to summer energy poverty, without necessarily having to undertake heavy work when they sometimes urgently need to install shutters,” they point out.