We have underfloor heating/cooling; the only mould we see anywhere now is a small amount on the skylight, and previously some in the bathroom that was due to a leaking roof the builders have since made good.

Condensation needs humidity, not just a lower temperature. In summer, this is rare, even though we're in Berlin which is essentially built in the middle of a huge area of low-lying marshy woodlands.

Their walls are autoclaved aerated concrete, which is pretty good at both insulating (so less cooling needed) and absorbing/diffusing humidity, so I think in their case it's fine.

It's a pretty cool material!