Night-flush cooling: Opens the building to cool night air, pre-cooling thermal mass for the next day (relies on passive/natural ventilation).
Evaporative cooling: Cools air via water evaporation; effectiveness depends on low ambient humidity, a real limitation in Normandy's oceanic climate, flagged rather than assumed to
Heat pump (air- or ground-source), reversible mode: The same physical unit as the backup-heating entry, run in reverse to actively cool instead of heat, one appliance doing both jobs rather than needing a second,