U-value transient problem

stergiani · Post by **stergiani** » Wed Oct 12, 2016 11:56 pm -1100

Hei!

I am using the sub-software of WUFI, U-value transient, and I have some problems.
In most of the cases, I get normal values for the U-values, but in one case I get negative values for it.
And when I try to export the results, although the fluxes look normal, the U-values are all zero.
Any idea what is going wrong?
Thank you in advance

Stergiani

Manfred Kehrer · Post by **Manfred Kehrer** » Thu Oct 13, 2016 1:27 am -1100

This happens sometimes in the summer and swing seasons when the average heat flux is inwards. Just uncheck those months.

saricioglu pelin · Post by **saricioglu pelin** » Thu Dec 22, 2022 9:58 am -1100

Hello ,
When i simulate my wall section i have no problem except inside layer as means WUFI VTT and WUFI bio but when i simulate heat transmission module i get yellow code so i understand that the U2 value (which is correspond condensation) is not enough but these conclusions are opposite. I am confused. Please help answer me.
Thank you.

Christian Bludau · Post by **Christian Bludau** » Thu Dec 22, 2022 9:17 pm -1100

Hi,

the U1 value and U2 values are based on the requirements for minimum thermal insulation of DIN 4108-2:
U1 = 0.73 W/m²K , according to DIN 4108-2 (2003) and.
U2 = 1.39 W/m²K, according to DIN 4108-2 (1981).
The yellow code means, that all values are below U2. That values do not directly correspond to condensation, as the dew point also depends on the room conditions.

WUFI Bio and VTT do a more accurate evaluation of mold spores under the surface conditions.

I would recommend to read at least the program help files (press F1 key somewhere in post process modules) to get an idea of what is evaluated.

Christian

saricioglu pelin · Post by **saricioglu pelin** » Sat Dec 24, 2022 10:06 am -1100

hello,
Thank you for answer but of course i also read it...I mean that my wall materials are not wood. And to fix this problem you mean change the indoor condition...ı understand...
Thank you.
Best

Christian Bludau · Post by **Christian Bludau** » Wed Jan 11, 2023 1:21 am -1100

Sorry, I do not remember, what I had in mind, when I wrote "with regard to the development of wood-destroying processes." Thats not rigtht. It does a more accurate evaluation of mold. It is not for the wood destroying process, that are different models by Vittanen.
Best regards
Christian

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