Storing travel trailer in a metal building

I had a 30'x40' metal building on some land I owned. Fully insulated, but not heated. The building never sweated. But the concrete slab did on cool humid days, even though it had plastic sheeting laid before the concrete was poured.

Because of the insulation, it never got overly hot inside, even closed up in TX summers of 100+. And inversely, it did retain some warmth inside when it was overly cold outside in the winter.