A controlled residential ventilation system (CRV) is a mechanical ventilation system for the defined supply and extraction of air in dwellings. A distinction is made between decentralised ventilation with several fans (individual units) and centralised ventilation where the ventilation ducts from several rooms are combined and connected to a single ventilation unit (central unit).

The controlled residential ventilation system can be designed as an extract air system, a supply air system or as a combined supply and extract air system. When fresh air is supplied and exhaust air removed at the same time, a heat exchanger can preheat the supply air using the heat from the extract air. With the aid of a heat pump, the waste heat from the extract air can be used to heat the supply air, for domestic hot water production or to operate a hot-water heating system.

An uncontrolled residential ventilation system is the natural ventilation of dwellings by means of window ventilation, leakage (infiltration) ventilation or shaft ventilation.