ᐅ Is it practical to install the supply air duct of a mechanical ventilation system underground?

I once heard that it is smart to run the supply air for the mechanical ventilation system through the ground for a few meters, possibly also passing it through a gravel bed to pre-condition the air.

This is supposed to slightly warm the air in winter and provide pleasantly cooler air in summer.

Now the question is, does this effort really make that much of a difference, and how many meters in length and at what depth should it be installed?

We were told that this makes sense when building with a basement and already excavating a trench. Otherwise, the costs apparently are not worthwhile, or in our case, the effort was too great (additional earthworks, etc.).

Well, maybe I would do that myself afterward, I have no idea what length would actually make sense.

Does dehumidification in summer significantly contribute to cooling?

I still live in the apartment and board up everything during the day to keep the heat out.
If the controlled ventilation system is running in the house during the day, wouldn’t that mean all the warm outside air is being pumped inside?

We had also considered that, but were advised against it due to the potential for contamination and the inability to clean or maintain the system—after all, you don’t just dig up the pipes again easily.