Convergence failure in air layer without moisture capacity

[Kostas]

Hello there,

I have the following problem.
I simulate a brick wall with internal simulation and a cavity between two bricks (I have split the cavity in three smaller ones using the standard air layer except in that in the middle)) and I get the following water balances
Water balance 1 - 3.45 kg/m2
water balance 2 - 5.72 kg/m2

while the water content is equal to 9.49 kg/m2 (start of simulation) and 5.93 kg/m2 (end of simulation).

The problem is in the air layer without moisture capacity, please look into the attached image.

I have already tried to refine the grid and used the adaptive time step control.
Is there any other way to overcome this? I know that I can use the standard air layer but I would like to investigate later the impact of envelope infiltration.

Many thanks.

Regards,
Kostas