Housing and renovation
The building envelope comes first
For older homes, continuous insulation of roofs and external walls usually does more for long-term efficiency than replacing the heating system alone. Controlled ventilation then keeps indoor air healthy as the building tightens.
Key components
Three layers that work together
Roof and attic insulation
Heat rises, so the roof or attic floor is often the first place to address. Continuous layers reduce losses across the upper envelope and limit thermal bridges at the eaves.
Exterior wall thermal breaks
Insulating the outside of walls, and interrupting bridges at floor slabs and window reveals, keeps the structure warmer. Installation detail matters as much as the material chosen.
Controlled double-flux ventilation
A tighter envelope needs a planned air supply. Double-flux systems extract stale air, recover heat from it, and bring fresh air in, which helps control humidity and indoor air quality.
Regulatory framework
Diagnostics and verified compliance
In France, the Energy Performance Diagnostic (DPE) is produced by a certified professional after an on-site assessment. It rates a building's energy and climate performance and supports renovation planning.
Aid conditions, eligibility rules, and performance thresholds change over time. Check the current requirements on official French sources and note the validity date of any figure before acting on it.