Central ventilation system and odors from outside

This is not a problem with a VOC sensor. We install them not only in the supply air but also in almost every room..VOC sensors via 1wire are also significantly cheaper than KNX sensors..

If I’m correct, Mycraft solved the whole thing via KNX with a VOC (or other) sensor in the outside air intake.
If the sensor triggers, the system is shut down until the sensor falls below the threshold again.
At least that’s how I imagine it

Yes, that’s how it works for me... generally, modern ventilation systems usually have an input for additional sensors even without KNX, but simply for an emergency stop, for example. Here you could start and just install a VOC sensor which then shuts down the system until the smell has dissipated...

Activated carbon filters (additionally) are also not a bad idea...

Thank you Mycraft
Did you install the solution on your side from the beginning or only after you detected odors from outside? Are there differences now? Do you know how long the system then stays off?

One more question: Cost factor for the VOC sensor?

In the course of the renovation of the system in 2014, I added the sensors... not only for the reason that odors were being sucked in... but also simply so that I have to worry about it even less and the system thus runs automatically as far as possible and provides the necessary air exchange rates.

The system stays off until the sensor reports: odor gone (including hysteresis)... that varies quite a bit...

The price was about 200 euros per sensor if I’m not mistaken...

I would rather think in the direction of activated carbon filters. In the best case, it is simply a replacement of the regular filter and starts at 5€. The system manufacturers often also offer modules. Not everything has to be technologized ... detecting bad air via sensor to shut down the system is at most a workaround, but not a solution.

Both have advantages and disadvantages. The sensor is good for short disturbances, the activated carbon filter is good if the ventilation should run even during longer neighbor chimney fires.

I would always use the activated carbon filter in addition to a "normal" filter. The latter is supposed to remove coarse dirt and dust, followed by the activated carbon filter against odors (and pollutants). If necessary, a fine filter can also help against smaller particles (pollen, but also soot), although commercially available filters IMHO do not help against fine dust.

For fully automatic operation, I would first want a humidity and CO2-based control. But such sensors also cost money and eventually need to be replaced.