[TRNSYS-users] Problem with the c-value to enter to obtain the desired Uwindow

[Tanguy MULLIEZ]

Hello,

It is the first thime I send a request to the trnsys users community, but I often look at the archives, which I find very useful.

I have a question regarding the c-value of the frame to be entered in the window type description :
It is said that the cframe-value has to be entered without the heat transfer coefficients αo and αi .

I usually calculate the Uframe to be entered using the following equation :
[cid:image003.jpg at 01CC9555.9FE55F30]

As Uw, Uglass and fframe are generally known from the beginning as a performance level requirement for the building.

My question is : how can we relate the Uframe of the above equation and the c-value to be entered?

Is it ok to write that Uframe = 1/[RSo + RSi + (1/cframe-value)]?
With RSo = 1/ αo = 0.04 m².K/W ?
With RSi = 1/ αi = 0.13 m².K/W ?

If not ok could somenone tell the right method to enter the c-value in order to obtain the desired Uwindow?

Great thanks !

Tanguy (Lyon)
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