Air Infiltration model IBP

[WUFIVOR25]

Hello,

I am looking to demonstrate that when a wall build up has a poor airtightness value, 8m³/(h·m²), that the moisture levels within the build up will increase significantly over a build up with a good airtightness level, 1m³/(h·m²).

I was able to demonstrate this in a Timber Frame construction, by introducing a moisture source into the OSB layer of the build up via the "Air Infiltration model IBP". This showed an increase in moisture for the poor airtightness model, although not as much as I would have anticipated.

However when I try this for a Masonry Cavity wall build up and a typical Steel Frame wall System I dont seem to see any noticeable differences in moisture levels within these build ups between the varying airtightness levels.

I have looked on the forum and online for help, but I dont see any specific questions that answer this.

Is there a defined way to demonstrate poor airtightness within WUFI Pro 6.7 and if so, how does one go about this?

[Christian Bludau]

Hi,
problem here is, that the source strength, which is introduced by the infiltration source is much lower than the water content the masonry wall already has. Therefore you will not see a difference. You can see the source amount brought in in the table "Status of last calculation". This is also depending on the height given. The infiltration source is thought to be used for lightweight constructions.

You might also use the air change source, but the problem remains. Dew-water introduced into the masonry always only will have a low effect and is redistributed quite fast.

Christian