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Re: [EnergyPlus_Support] Window5 data vs IDF dimension
You are correct that the dimensions of your window as input in the IDF will take precedence over the dimensions of the window in the Window5 data file, *UNLESS* the window in the Window5 data file contains two sections that have different glazing systems, in which case the Window5 dimensions will be used. See details of this under "Importing Windows from Window 5" in the "Group - Thermal Zone Description/Geometry" section of the Input/Output Reference.
The frame that is part of the Window 5 data file will be used to create a WindowFrameAndDivider object that will be assigned to the window for EnergyPlus analysis. EnergyPlus will generate a warning if the dimensions of the window in your IDF differ from the Window5 dimensions by more than 10%. This warning indicates that some inaccuracy may result because of the different area and perimeter relationships between the glass area and the frame. Unless you are especially concerned with the frame effects, you should create a simple narrow frame in your Window5 file to reduce these differences. It is not possible to create a Window5 window system for export to EnergyPlus without including some type of frame.
The importance of modeling your windows precisely depends on what you are trying to analyze. If you are interested in daylighting effects, then it is important to model the windows accurately. If you are only looking for general thermal effects, then this is not as important.
Rob Hitchcock
----- Original Message -----
From: Ery Djunaedy <ery@xxxxxxxxxxxx>
Date: Thursday, June 14, 2007 10:41 pm
Subject: [EnergyPlus_Support] Window5 data vs IDF dimension
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> All,
>
> I use Window5 data file for my windows properties, and I would like to
> know is the best strategy to model the window (detail vs accuracy vs
> time).
>
> In IDF file, I modelled the windows as a long continuous horizontal
> stripe in the external wall. However in Windows5 I modelled the
> windows in the correct dimensions (glass+frame).
>
> I initially thought that the Window5 data will take precedence over
> the IDF dimension. But referring to the manual, this is not true. When
> there is a discrepancy in the dimension between IDF and Window5, then
> IDF dimension will take precedence.
>
> The glass properties will be taken from Window5, but the dimension
> will be from IDF file.
>
> But what about the frame? The manual does not mention anything about
> the frame, will the properties be taken from the Window5 file or from
> IDF?
>
> This brings the question on what is the best way to model the window.
> If we want to justify, for example, that a certain window is so good
> that we do not need the perimeter heating, then we need to model the
> frame as detail as possible.
>
> Do we really need to model every window exactly as the dimension is?
> This will make the simulation time increased tremendously.
>
> Any suggestion is very welcome.
>
> Thanks,
>
> Ery
>
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