Central Heat Recovery — Whole-House Ventilation System

Central heat recovery ventilation (often called MVHR — Mechanical Ventilation with Heat Recovery) uses a single air handling unit, typically installed in a utility room, attic, or basement. The unit is connected to all rooms through a network of insulated ducts.

Stale air is extracted from "wet" rooms (kitchens, bathrooms, utility rooms) and passed through a counter-flow heat exchanger. Fresh outdoor air passes through the same exchanger on the opposite side, absorbing up to 95% of the heat from the exhaust stream. The pre-heated fresh air is then distributed to "dry" rooms (bedrooms, living rooms, offices).

The entire house is continuously ventilated with filtered, tempered air — without opening a single window.

Central heat recovery must be designed during the building planning phase. Retrofitting ductwork into a finished building is possible but significantly more expensive and complex.

Plan during construction

The ideal time to integrate central ventilation is when planning your new build or major renovation. Key decisions include:

• Unit location — Utility room, attic, or basement. Central position minimises duct lengths.
• Duct routing — Through suspended ceilings, raised floors, or dedicated shafts. Plan routes before walls are closed.
• Room layout — Supply valves in bedrooms and living rooms, extract valves in kitchen and bathrooms.
• Duct material — EPP ducts (pre-insulated, no condensation) or insulated steel/flexible ducts.

Retrofit considerations

If you're renovating an existing building, ductwork can be routed through:

• New suspended ceilings (adds 15–20 cm)
• Along walls with boxing (less aesthetic but functional)
• Through existing unused chimneys or shafts

If retrofitting ducts is too disruptive, consider decentralized heat recovery as an alternative — no ductwork required.