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, dedicated air-conditioning unit. Worth being precise about the efficiency claim: in cooling mode, a reversible heat pump and a cooling-only air conditioner of the same SEER rating perform essentially identically, both use the same vapor-compression refrigeration cycle, so reversibility doesn't make the cooling itself more efficient. The real gain is avoiding the embodied footprint, cost, and space of a second, cooling-only machine on top of the heating one.
Note: Cost, carbon and footprint are rated against the other options for this same need, not in absolute terms.
No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.