Determine percentage of solid window area
(Ifc)Windows can be surprisingly complex but I wonder if there is a method to determine how big part of the apparent window area that is solid or transparent? The method does not need to be perfect.
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@Max are you looking for the glass area as opposed to the overall area of the opening in the wall? like the yellow bit in the window elevation. I was wondering about this for Passiv Haus calcs
Thanks @Nigel for the image, this is exactly what I am looking for.
@max could this be determined by the glass 'material' to differentiate it from the frame I wonder?
@max also it would be good to get perimeter of glass panels too, that would help for thermal calcs in Passive Haus
I agree, perimeter of glass panels would also be useful as well but am not sure if this is enough for calculating Uw. You probably need a full 2D/3D FEM analysis. Right now I am mostly interested in approximating solar transmittance.
I might sound naive here but, wouldn't you have that info (glass area) from the window type itself? just by actually measuring it? unless you have so many different types in a building even manually it might take just a few minutes
by knowing the number of instances you get your total area, you can even save the glass pane area in a custom pset I think, but of course I'd be very interested to know if there were another way to do it
cheers
I just found that I asked this question a year ago at https://community.osarch.org/discussion/1325/blenderbim-list-window-fraction, sorry about this. Anyway, about 90% of the Ifcmodels I have does not contain the GlazingAreaFraction property in Pset_WindowCommon and many of the once that does gives very strange values, larger than 1 so I need a more robust method.
It would not be too hard for simple models but for more complicated windows I don't know. Doing a topology-based analysis would also depend on the quality of the input model. You could set up a script to render your windows in svg and add up the areas of the window material and the frame material and divide the two.
I can see that GlazingAreaFraction is contemplated in Pset_WindowCommon of IFC 4 and 4x3.2 here
so the problem is to find a way to automatically calculate it ? do you have so many different window type?
I am thinking to use the frame thickness in the parametric window and somehow subtract it from the overall dims..
We are talking about a lot of IfcWindows in a lot of models so it needs to be automized, prefarably without BlenderBIM.
..I never understood the tendency of architects to use so many different combination of windows, it looks like it gives them pleasure to have a long schedule full of different ones, often times slightly so..
just kidding ! ;p