Question about u-factor result options

[Hanieh Nasirpour]

Hi

Can someone please explain to me in what situation should the total length option be used for the u-factor result? I checked the THERM 7 simulation manual but there was no explanation about this option and it was only stated that the projected in glass pane option is generally used except in some special cases in which you should use the custom length option. However, in some cases choosing total length instead of projected in glass pane can result in more acceptable and logical u-factors. 

[Ventura, Ed Ramir]

total length measures the entire length of the u factor surfaces tagged identically. I would use it only if your section is flat, example would be a section of a plain stud wall.

But once you have a section with a cove then you should not use total length

On Mon, Feb 10, 2020 at 7:25 AM Hanieh Nasirpour <airs...@gmail.com> wrote:

Hi

Can someone please explain to me in what situation should the total length option be used for the u-factor result? I checked the THERM 7 simulation manual but there was no explanation about this option and it was only stated that the projected in glass pane option is generally used except in some special cases in which you should use the custom length option. However, in some cases choosing total length instead of projected in glass pane can result in more acceptable and logical u-factors. 

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[Robin Mitchell]

What you use for the U-factor choice will depend on what you are wanting to calculate. 

In the US, the NFRC (National Fenestration Rating Council) requires that U-factors are calculated based on projected dimensions, not total length. That is why the default selection in the U-factors dialog box is "Projected in Glass Plane". 

Robin