Centralized and decentralized ventilation systems both have their advantages and are chosen depending on the building's size, usage, and energy efficiency.
Air handling unit serving multiple apartments
In centrally placed ventilation system one air handling unit serves multiple apartments in the same floor/corridor or even all apartments in the whole building.
In apartment placed ventilation system each apartment has it's own individual air handling unit.
Centrally placed apartment specific ventilation
Disadvantages
Wall placed ventilation without ducts
Wall mounted heat recovery ventilation without incoming air ducts is ideal for renovation.
A complete system for ventilation, heating and cooling
in multiapartment buildings
