can't find psi value

[Juergen]

Hi, 

I'm writing from Europe, so I am used to european standards.

I'm using Therm 7.8.80.0.

I don't use this for detailed window/glazing calculation, I use it to calculate thermal bridges in facades in general.

I have drawn and imported a horizontal cross section of a facade, it is a stell steel frame with panels on both sides, insulation in the cavity and the steel profile in the center. The stell profile generates a thermal bridge.

I assigned a U factor tag to one of the boundaries and got a Ufactor result, which is the total heat flow through this cross section. 

So now to obtain Psi value, I would need to calculate the 1 dimensional simplified Uvalue through the unaltered cross section (no steel), this can easilly be done manually, and then calculate the differential between both.

I checked this with my results with Psytherm software, and the result is accurate.

The question is how to obtain this Psi value directly with Therm, I didn't find this anywhere in the manual or going through all the buttons in the program.

Another question is, how to get a calculation report. There seems to be a bug in the file/report option, it doesnt do anything.

Thanks for your help.

In any case this program seems to be really good and is calculating very fast. Offering this for free is really great.

Best regards

[archi...@gmail.com]

Hi Juergen.

The answer to your question is: Therm does not give directly the Psi value of a thermal bridge. 

The correct procedure to obtain the Psi value is approximately the one you described.

Actually the correct procedure adopted in Europe is described in EN ISO 10211:2017 Standard, and precisely in Ψ  = L2D -  Σ U x l, where L2D =  Φ /  ΔT 

Φ is directly obtained  with Therm FEM calculation, U of the unperturbed structure is obtained both with manual calculation (as you have written) or with Therm (with a model of the same structure without the part that creates the thermal bridge).

Some brilliant Therm users have implemented procedures with the GrassHopper software that allow them to automate this calculation. 

Unfortunately I'm not so brilliant! ;-)

Ciao

Fabrizio