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Ventilation and passive house

The importance of a good ventilation system in a passive house

Ventilation and passive house, why is it necessary ? A passive house is airtight and very well insulated, it is therefore essential to renew the indoor air to ensure its quality. Several types of ventilation can be considered but we will mainly focus on the solution used in passive constructions. For more details check our page dedicated to air renewal

  • Natural ventilation consists of manually opening the windows. It strongly depends on temperature differential, wind speed and pressure, and also on the behavior of the tenants. To be efficient, the minimum required is every 3 hours. 
  • Due to the randomness of natural ventilation, all passive buildings are equipped with dual-flow heat recovery ventilation.

Indeed, it makes it possible to limit unpleasant odors, limit the humidity of the indoor air and thus avoid the development of mould, to minimize the concentration of CO2 and other pollutants.

It also provides indoor air conditioning:

  • clean air thanks to filters
  • heating / cooling through the heat exchanger
  • humidification / dehumidification through moisture recovery

How does dual flow ventilation with heat recovery work?

It consists of extracting polluted air from areas such as the kitchen, bathroom, toilet and provides fresh air to living rooms such as bedrooms and living rooms.

A heat recovery unit refers to an exchanger that recovers calories from polluted air to preheated incoming cold air.

Today, heat exchangers can recover between 75 and 95% of the heat from the extracted air.

Ventilation delivers the right amount of fresh air for a healthy indoor climate, which is about 30m³/h per person.


Check out this page to find a list of companies in Portugal specialized in ventilation systems for passive houses.