Heat recovery ventilation (rekuperace)

Rekuperace is the Czech everyday term for balanced mechanical ventilation with heat recovery. A unit with fans extracts air from the kitchen, bathroom and toilet and supplies fresh outdoor air to living rooms. Both airflows pass through a heat exchanger, where the warm outgoing air warms the cold incoming air without the two normally mixing. The air is also filtered.

Types and how to read the data

• A central unit ventilates the whole house or flat through ductwork; it is best planned during construction or a major renovation.
• Decentralised (room) units are fitted into the external wall of individual rooms and need no ducts.
• Heat recovery efficiency, in per cent, shows how much heat from the outgoing air is returned. Decree No. 264/2020 Coll. uses a reference value of 60% for replaced systems; good units reach more, according to manufacturers.

Why it is installed

After insulation and new windows, a house is more airtight and far less air leaks in and out through gaps. Decree No. 146/2024 Coll. requires, for habitable rooms while occupied, an air exchange of at least 0.5 room volumes per hour or 25 m3 of outdoor air per hour per person. Heat recovery ventilation provides this without opening windows and with less heat loss, which is also reflected in the energy performance certificate. It is a common feature of very low-energy new builds.

What to watch out for

Heat recovery ventilation is not a heat source - the house still needs heating, for example a heat pump. The unit uses electricity for its fans and needs maintenance: regular filter changes or cleaning and occasional checks of the exchanger and ducts. When buying, ask about the unit type, year of installation, ventilation design and when the filters were last changed.

Frequently asked questions

Is it the same as air conditioning?

No. It exchanges air and returns part of the heat, but does not actively cool the air. Cooling is provided by air conditioning or some heat pumps.

Is it suitable for a flat in an apartment building?

Yes, either as a central unit for one flat or as room units. Openings in the facade and ducts through common parts of the apartment building must, however, be agreed in advance with the owners' association.