According to BobR :

It is the only method I have seen yet that would provide an equally
effective benefit in both summer and winter no matter the local
climate. The major difference would be in northern colder climates
the heat exchanger would need to be buried deeper in order to find a
stable temperature zone.

If the exchanger is horizontal, and only by a few feet (unless you're
comparing Miami and Resolute Bay of course ;-).

Many of the systems are vertical (eg: the ones we were looking
at use 100' deep wells), so different frost depth makes very little
difference.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.