WUFI

Hi,

I am going to introduce the next case for 2 different climate : Madrid (Spain) and Lund (Sweden)

Variables:

-Moisture source (1% Rain): no moisture source, 5mm in the innermost side of the brick or 5mm in the outer most side of the external insulation
-Water repellent or not

both models are the same:

Grid

-Min # of elements x:2 y:2
-Max # of elements x:2 y:2

Materials: see image Water repellent: 1 cm (brick), water vapor diff resuist facotr: 15 & water absorption coeff: 0,0018 kg/m2 s1/2
Steel: mu=32800, heat capacity=4700J/kg K, Porosity= 0,001, DWW &DWS=0, Defaut moisture storage function

Initial conditions: Default

SurfaceWeather

Boundary condition 8 & 17 W/m2K for external and internal respectively
Short wave absorption: 0,68 (Brick)
Rest of parameters: Default

Computational parameters

Convergence critirion: 1e-6
NSW:40
URF (RH): 0,3
Activation of Time step control
Activation of Rational interpolation in soption isotherm

Hopefully, I did not missed anything unless let me know please

Case 1: Madrid See image below and below jajaja
my questions are;

Does the graph make sense? I meant it looks that the RH in the brick is higher than in the inner layers of the assembly (water vapour going form inside to outside) int he winter and in the same the outdoors temperature is higer than indoor so drying rocess to the interior so higher RH in the interior layer assemblie rather than Brick what I think it does make sense, but

I do not see a big difference in the plots when I model a moisture source and water repellent cases, why?.

if the grid is 12mm width but I define that the moisture source as 5 mm see image, what does it have priority?

Case 2: Lund Sweden see image below

I made the next odd observations and I do not what I do wrong

- there is only difference in the results for water repellent or not in the brick after April, why?

-no difference if I model a moisture source (5mm) in the outermost side of the external insulation or innermost side of the brick, why?

- I MODEL air cavity as 50mm with no additional moistur capacity or 1mm (Air layer 50mm)-48mm (Air layer 50mm without additional moisture capacity))-1mm(Air layer 50mm), and no differrence in the graphs , why?
any other comments are more than welcome

Thanks in advance

i forgot to ask if the rain moisture soruce in the party wall should be modelled along the wall as you can see in the image or just in on sport of the wall

Hi Alberto,
sorry, it is not easy to work through the construction and courses and needs a lot of time. But I try to answer your questions.

Does the graph make sense? I meant it looks that the RH in the brick is higher than in the inner layers of the assembly (water vapour going form inside to outside) int he winter and in the same the outdoors temperature is higher than indoor so drying process to the interior so higher RH in the interior layer assemblies rather than Brick what I think it does make sense, but

I can not answer this without knowing the evaluation positions, but sounds good.

I do not see a big difference in the plots when I model a moisture source and water repellent cases, why?.

With or without source?

if the grid is 12mm width but I define that the moisture source as 5 mm see image, what does it have priority?

The source only can be distributed over full calculation grid elements, so the 12mm are used here - maybe try to use a finer grid here. That will allow a better distribution of the moisture.

- there is only difference in the results for water repellent or not in the brick after April, why?

That may be related to a heavy rain event in April?

-no difference if I model a moisture source (5mm) in the outermost side of the external insulation or innermost side of the brick, why?

I have no idea. Maybe the material is redistributing quite fast, maybe the source do not bring in water, maybe start with checking your climate file. Does that even include rain? Is the source connected with the right boundary condition?

- I MODEL air cavity as 50mm with no additional moisture capacity or 1mm (Air layer 50mm)-48mm (Air layer 50mm without additional moisture capacity))-1mm(Air layer 50mm), and no difference in the graphs , why?

There will be mostly a difference, if dew water is formed. The long term behavior is about the same.

i forgot to ask if the rain moisture source in the party wall should be modeled along the wall as you can see in the image or just in on sport of the wall

The source is usually intended to take into account local leaks (for example, in the area of the window sill). Therefore, it should be placed in the affected area. If water can run behind the entire façade, the source also can be distributed over the entire width.

Christian