WUFI

I have been using WUFI Plus 2.5.3.0 to model the energy use and heat/moisture transfer in very small residential buildings. I have a few questions that I could not find an answer to on the wiki or the forum or in the manual.

1. I need to know how the software model the connections between walls, ceilings, and floors. For example, with the wall/floor connection, does WUFI assume that the walls are built on top of the floor, so that the top layer of the floor is in contact to the bottom face of the wall, or that the floor is built inside the walls, so that the perimeter of the floor is in contact with the inside layer of the walls? Similarly, in the wall/ceiling connection, is the ceiling on top of the walls, so that the upper face (i.e. top plate) is in contact with the inside layer of the ceiling, or is the inside layer of the wall in contact with the perimeter of the ceiling? Or is there some other configuration that is used to model the connection?
If there is a default configuration, how can I override it?

2. Also, how is the top of a wall assembly modeled? The buildings I am working with are very simple 3-room structures (government subsidized housing in South Africa). The walls are two layers of masonry with a 40mm air gap between the layers. I can not find a way to indicate that there is a top plate at the top of the wall, and that the air gap is not open at the top. Is there a way to do so?

3. Does the assembly of a slab floor apply to the perimeter faces? I have rigid foam board insulation underneath the slab (horizontal) and on the perimeter (vertical). The assembly shows insulation as the outside layer, and concrete as the inside layer. In this case, does 'outside' refer to all five faces of the slab that are in contact with the ground, or only to the bottom horizontal face?

I tried to attach my file, but the .mwp extension was not allowed, and uploading a zip timed out. Any suggestions on how to attach my WUFI plus file? It has three cases with increasing insulation levels for the walls, ceiling, slab, and windows. In Case 1, these assemblies have no insulation (and single-pane windows); in Case 2, these assemblies have a moderate level of insulation (and double-pane windows); in Case 3, these assemblies have a higher level of insulation.
When I run the simulations, I get what seem to be erroneous values for the heating load (Case 1: 10773.8 kWh, Case 2: 4204.6 kWh, Case 3: 30.3 kWh) and the floor accounts for an unbelievably large portion of the heat loss.
What could be causing these results?

Thank you for your help.

Thank you very much for posting the questions in the forum.

1. WUFI Plus standardly calculate the the heat and moisture transport across all building componentes as one-dimensional. There is no direct heat and moisture transport between the walls and floors and their layers. They are coupled with the indoor climate within the zones. So on each component you can only define the boundary conditions on the inner and outer side. But if you want to model the heat transport (no moisture) in 2D or 3D you can add those special details as 3D-Objects. More information about this you can find here: http://www.wufi.de/ibp/publikationen/ko ... lation.pdf
and here: http://www.wufi-wiki.com/mediawiki/inde ... 3D-Objects

2. If you have inhomogeneous building components it is might helpful to define different components. You can model them within the 3D-visualtization and the vertices, or maybe the faster way is to use the "window/opening" tool accessable with a right click on a component. There you can define a special part in the component also listed in the project tree (as transparent component). But you can switch the type to opaque and define another assembly. However, same as before, the heat and moisture transport is only calculated one-dimensional. So there is no direct interaction between those components.
An assembly including an air gap, defined with one layer using the generic air layer as material doesn't regard the air exchange between this gap and inner or outer climate automatically. So the gap is sealed on each side. If you want to model the infiltration in the gap you have to define inner sources in this layer, or on the surface of the adjacent layers: http://www.wufi-wiki.com/mediawiki/inde ... .22Edit.22

3. Outside does refer only to the bottom horizontal face (1D transport). Respectiveley, only to the side where the normal vector of the component point to. You can show/hide the normal vectors in the 3D-visualisation with one button on the left, and by selecting a component.

For the floor slap, a component coupled with the ground, you have to define the ground climate. So if you have an unbelievable very hight heat loss via this compoent, you have have to check the "optional climate" attached on the outer side of this compont. You might often can model it with a user defined sine-curve. But of cause, the parameters (e.g. mean temperature) must be adjusted to the outer climate.
The zip-file upload should work. If not, you can send the file to support@wufi.com