Condensation behind metal ceiling

[yihao92]

Hi,

I am running a condensation simulation for a non insulated metal ceiling panel.
I have 2 model with the same air gap thickness, material and boundary condition but with different number of timber ceiling joist modelled.

Model 1- one ceiling joist (condensation was noted at the back of ceiling panel)
Model 2- 2 ceiling joist (no condensation noted)

the metal is subjected to 24 degree constant temp, where the external boundary is singapore tropical climate file.
condensation should happened because the surface temperature is lower than the dew point as model 1.

But i am not sure why condensation not occur when i introduce another timber joist

[Christian Bludau]

Dear yihao92,
please check the values of the water content in WUFI Graph. You two diagrams have different scaling. You also can adapt the colors. Try to do a right click on the legend.
Christian

[yihao92]

Thanks Christian for your reply.
The moisture content do increase .

I also observed another interesting phenomenon but i am not sure on the cause.
I change the roof space varies from 0.3m to 1.2m air gap with the same boundary condition and material.
The top is the roof and bottom is the ceiling. the legend is set to be same.
but the rh behind the metal panel appear to be lowest at roof space 0.75m.
i am not sure why?