Boundary conditions - new user

[Juergen]

Hi, 

I just installed the program and it runs fine. I used to work with Psytherm commercial software to calculate thermal bridges in construction details, not specifically windows.

I see that the program allows to create own materials and boundary conditions.

But I don't know how to define a boundary condition for external walls or internal walls.

According european ways of calculating U values and Thermal bridges, the  boundary condition is defined by a thermal resistance value in m2K/W. For external surfaces, the value is fix (Rse=0,04m2K/W) and for internal walls (vertical surface) it is Rsi=0,13 m2K/W. 

How to create this boundary condition? In the options for boundary conditions / simplified model I see "Film", but the unit is W/m2K. Should I input the reciprocal value of Rse or Rsi? This looks strange to me.

Thanks for your support

Juergen 

[archi...@gmail.com]

Hi Juergen

You can create your personal Boundary Conditions in "Libraries/Boundary Conditions", setting a Temperature and a Film coefficient which is simply the inverse of the surface resistance value.

So Rse = 0.04 m2K/W corresponds to a film coefficient = 25 W/m2K, Rsi = 0.13 m2K/W to a film coefficient = 7.692 W/m2K and so on for all the other Rs values provided in EN ISO 6946.

Personally I give my personal BCs names consistent with their actual characteristics in temperature and Rs.

        

Ciao

Fabrizio