Answer: in old dwellings.
Distributed mechanical ventilation (or VMR) is a type of ventilation that sometimes replaces VMC in renovated old homes. Its major advantage is that it does not require the passage of ducts throughout the housing. VMR is therefore much less expensive, and easier to install than a dual-flow CMV. Instead of vents and ducts, independent air extractors are installed in each humid room (kitchen and bathroom), which will take care of sucking the stale air. Note however that the extractors are not very aesthetic, and are reputed to be quite noisy. VMR is now prohibited in new homes, because it no longer corresponds to current regulatory standards, but you can still use one in old homes which are not (yet) subject to the same rules. You too, send us your brico question