Air Layer vs. Air Layer Without Additional Moisture Capacity

[Hayden Robinson]

In my WUFI Pro Workshop, I understood that we instructed always to use the standard Material Data Base Air Layers, not the Air Layers without additional moisture capacity. However, the Info Text at the bottom of the Generic Materials page seems to suggest the opposite. Can anyone straighten me out on which is the appropriate selection? Does the choice vary according to circumstance? For example, would a still air layer, a ventilated air layer, and an air layer inserted in order to locate a moisture source adjacent to a non-porous material use different settings?

Thanks,
Hayden

[Christian Bludau]

Hello Hayden,

the "air layers xx mm" do not have a moisture storage function. For that reason an internal one is used, which produces to high water contents. As WUFI calculates with the RH, the long time over all behavior with this air layer is right, but you must not analyze the water content. You will get too high values. In many cases, the water content of the air layers is not the question, so these layers are usable. And the solving of the equations is much easier for that. In WUFI 2D it is usually better to use this air layers.

The "air layer xx mm, without additional moisture capacity" has a realistic moisture storage function, but as mentioned the solving is slower. You have to use that if you have e.g. questions about the amount of dew water in the air layer.

Please keep in mind to use the air layers always in the given thickness as the values include assumptions for the convection and radiation. If you need a different thickness, please refer to the WUFI Help file.

Christian

[Hayden Robinson]

Thank you Christian, I appreciate your help.
Hayden