Simulating attic ventilation

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MWE_MOE
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Simulating attic ventilation

Post by MWE_MOE » Mon May 06, 2019 10:14 pm -1100

I am trying to simulate attic ventilation i af pitched roof.

I have seen examples where the airspace between the truss and insulation has been simulated using 30 mm standard airlayer, 130 mm airlayer without additional moisture with 30 ACH, 30 mm standard airlayer.

Is this the correct way to simulate an atticspace?

Christian Bludau
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Re: Simulating attic ventilation

Post by Christian Bludau » Mon May 06, 2019 11:15 pm -1100

Hi MWE_MOE,
in my eyes, an attic space can not be realistically represented by an air layer. Please keep in mind, that the bigger the airspace is, the more convection will occur. And that can not be expressed by using a source.
It would be better to handle the attic space as a separate room with its own climate, so as a boundary condition in WUFI Pro and not as a layer.

In WUFI the air layers contain effective values for the permeability and the thermal conductivity which include the convection and radiation in the layer. So they always have to be used in thickness given in the database. It is not possible to add air layers with same or different thickness to get a higher thickness. So the example you mention is wrong, if done with WUFI.
Please see also the material information text of the air layers.

Christian

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