ᐅ Retrofitting an existing centralized mechanical ventilation system with an earth-to-air heat exchanger?

Hello

In our newly built house from 2013, we have a central Vallox mechanical ventilation system installed in the attic.

Last summer, however, it was so that the system can only blow air into the house at the outside air temperature, which means that because of the sun shining through the windows, it sometimes became unbearably hot inside. Of course, the mechanical ventilation system can’t do anything about that, since it is not an air conditioning system...

I have seen a house where the mechanical ventilation system was combined with a ground heat exchanger, which cools the incoming air in the ground during summer or warms it slightly in winter...

Has anyone retrofitted something like this before? Installing the ductwork is less of a problem; the bigger issue is that an air duct has to be run along the external wall to the intake opening of the system. This means about 8 meters (26 feet) of duct (on the east side of the house), which is exposed to the sun at least in the morning and forenoon and thus heated by the outside air during the day. Running the duct inside the building would involve a significant amount of work...