Simple study case



I’m Trying to simulate a simple box with no mass material single layer construction for all surfaces. The weather file is custom-made to have constant temperatures of 20° then 10°. All other weather values are constant (rad. 0, wind 0, rel. humidity 50).
All internal loads are set to be 0. What I would expect to see is that the inside temperature will pretty much try to follow the outside temperature with a slight delay.
However, in the simulation, the inner temperature falls down and the humidity jumps up.

Can someone explain what’s going on?
P.S. I’m not an engineer, so I expect I might be doing something very wrong.

Test (561.8 KB)
test.epw (1.4 MB)