There seems to be some misconception about opening windows in a Passivhaus. The simple answer to the question is YES.

Actually, there are many reasons why there needs to be at least one opening window in each habitable room. One of the best options is the tilt & turn windows, which has to do with maintenance and overall performance reasons.

1) During warm periods, opening the windows is the easiest, cheapest, most effective and environmentally friendly way to cool your home, using purge or cross ventilation. Of course, this applies to climates such as the UK, where the night temperature in summer, in most cases, is below 20 Celsius degrees.

2) People don’t like to miss the opportunity to use windows as a connection to the outside world, so they strongly prefer to choose whether they keep the windows open or closed.

3) Cleaning a tilt & turn window is much easier than cleaning a fixed one. You can clean both the outside and inside.

4) Monitoring post occupancy evaluation results, we came to the conclusion that there is not a risk of not having a sufficiently warm house or having a lot higher energy demand if users keep the windows open. Of course, the only side effect here would be the slightly higher energy bills.

5) Even during cold periods, it is sometimes nice to open windows to let fresh air into the house, especially after having more people gathered in your home.

6) An opening window could also save someone’s life in a case of a fire or panic situation (earthquakes).

Based on all these above, it is useful to emphasise that at least one opening window per room used for living is a prerequisite for Passivhaus buildings in order to be suitable.