The renovation of the residential building stock is becoming a central lever for decarbonisation, although its impact on health remains ambivalent. This analysis shows that, while energy interventions can reduce consumption by up to 80%, they can also generate unintended effects on indoor environmental quality (IEQ), particularly when airtightness is prioritised without adequate ventilation.

The balance between efficiency and well-being is structured around four dimensions: thermal comfort, air quality, lighting, and acoustics. Improvements in insulation or airtightness may increase the risk of overheating or concentrate pollutants such as radon and volatile organic compounds, while solutions such as controlled ventilation or IoT technologies can help mitigate these effects.

The study highlights the need to integrate health metrics into retrofit policies, moving beyond approaches focused solely on energy. Progress towards more holistic strategies, adapted to climatic and social contexts, is essential to ensure equitable and sustainable benefits in the built environment.