What is ventilation?

Ventilation (in Dutch: ventileren) is the continuous, gradual replacement of indoor air with fresh outdoor air, through vents, ducts or a ventilation system. It removes the moisture, CO2, odours and pollutants produced by living, cooking, showering and breathing. Ventilation is not the same as airing (purge ventilation): opening windows and doors wide for a short time to change a lot of air quickly, for example after a shower or cooking.

Ventilation systems

In the Netherlands, ventilation systems are referred to by letter:

System A: natural supply and natural extract, mainly in older homes.
System B: mechanical supply and natural extract.
System C: natural supply through window vents and mechanical extract in the kitchen, bathroom and toilet.
System D: mechanical supply and extract, known as balanced ventilation, often with heat recovery.

What the Dutch rules require

In the Netherlands, the Besluit bouwwerken leefomgeving (Bbl) sets minimum air exchange rates. For a new home (article 4.122) these are at least 0.9 dm³/s per m² in a habitable area and 0.7 dm³/s per m² in a habitable room, each with a minimum of 7 dm³/s. A room with a cooking appliance needs at least 21 dm³/s, a toilet 7 dm³/s and a bathroom 14 dm³/s. For an existing home (article 3.67) the requirement is 0.7 dm³/s per m² of habitable room, with a minimum of 7 dm³/s. New homes must also have a purge facility, such as an opening window. Outside the Netherlands, your own national building regulations apply.

Minimum air exchange rates for a new home in the Netherlands under the Besluit bouwwerken leefomgeving (Bbl), article 4.122. Outside the Netherlands, your own national building regulations apply.

Application

Good ventilation prevents condensation, mould and timber rot and keeps the air healthy. The more airtight a house, the more important a well-planned ventilation system becomes: after insulating and draught-proofing, the accidental ventilation through gaps disappears.

Tips

Ventilate all the time: keep vents open and mechanical ventilation running, including at night and in winter.
Adjust the setting: turn extraction up while cooking and showering and let it run on for a while afterwards.
Let air flow: leave a gap under internal doors or fit a transfer grille.
Filters and valves: replace balanced-ventilation filters as the manufacturer recommends and clean the valves. Do not twist extract valves, as they have been balanced.
Crawl space: never block crawl space vents.

Related terms

Ventilation grille
Natural ventilation
Mechanical ventilation
Balanced ventilation
Airtightness
Condensation

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