RE2020 Thermal Study
Saint-Étienne, AURA

In Saint-Étienne, thermal studies focus mainly on the existing stock: the building stock inherited from the industrial era, often in stone or brick and with high heat loss, represents the area's main energy-saving potential and the main RE2020 challenge in renovation. The altitude of the conurbation appreciably lengthens the heating season compared with the neighbouring Rhône valley, which shifts the balance point of the scenarios. The presence of a district heating network also opens up a favourable lever on the carbon indicator, provided the connection is arbitrated before the preliminary design stage (APS) and not added afterwards.

Summer comfort is the sticking point of the RE2020 in Saint-Étienne: on exposed façades, the degree-hours (DH) threshold is quickly exceeded, all the more so in the south of France. Dynamic thermal simulation arbitrates between thermal inertia, solar shading and natural ventilation before the building envelope is fixed.