I am simulating a 10 floor simple cuboid building. The size of one floor is 230 square meter with 3 m height. when I simulated for energy requirements it took 5 min. But then I added horizontal shading on all windows and ran the simulation again. However, this time it is taking too long to run(more than 10 hours). The only difference between the 2 simulations was the addition of horizontal shading.
Kindly help if there is any way I can reduce the timing .
I`m having the same issue even with smaller 1 cube!! the only difference was the addition of a vertical shading in front of a fully glazed face? any tips would be appreciated .
hi @cbenbacha, openstudio and energyplus aren’t quick, some things that can help speed things up are simplifying glazing in order to simplify shading as the shading calcs take a while.
How long is your model taking to run?
What does it look like?
best
-trevor
Hi @TrevorFedyna, thanks for your reply.
I’m encountering similar issues to those previously mentioned by others regarding complex shading. Specifically:
I’ve attached a simplified shoebox file with a vertical complex shading that illustrates the current issue. Feel free to review it.
Here are some posts with similar issues:
1- Energy simulation, the run time is very high
Shading Issue.gh (252.2 KB)
Shading issues.3dm (406.7 KB)
@cbenbacha I definitely will in the morning, this sounds like it may be a bug @chris may want to hear about
best
-trevor
Hi @TrevorFedyna,
Just checking back to see if this issue caught any attentions or by any chance you got a moment to look into it.
@chris your input is highly needed here. I would appreciate any tips or recommendations.
Thanks,
If shades that look like this:
… take anything less than a 3 hours to complete the EnergyPlus simulation, then they are not being modeled in the simulation.
Modeling shades like that is not practical for EnergyPlus. E+ is not a rendering software like Radiance so you can’t just throw unformatted geometry at it and expect it to churn through it in seconds.
If you want to actually understand the impact of something like this shade on building energy use, then model these shades using a transmittance fraction applied to the Window Construction Shade. And just calculate the transmittance using the opening fraction of your screen design.
Otherwise, you’re really just wasting your time and computing power.
Maybe I’ll just add the explanation for why one simulation took longer than another. Most of these shades have parts of them that are smaller than 1 cm, which is the geometry tolerance of EnergyPlus, below which EnergyPlus cannot model the geometry. In the first simulation with Model-assigned shades, all of the shades were removed because the way that they got subdivided resulted in geometry smaller than 1 cm. In the other simulation, it seems that 6 shade objects got lucky and were subdivided in a way that they passed the 1cm limit:
And those 6 shades result in the simulation taking over an hour. So, yea. Don’t model geometry like that for EnergyPlus.
Thank you so much, @chris , for your explanation. Now I understand the limitations of the software better. You’re absolutely right—the shading geometry is quite complex, which makes it difficult for EnergyPlus to handle accurately. Luckily, the daylighting analysis, ASE, and direct sun hours exposure all worked out, so for the energy simulation, I will follow your suggestion and use the alternative methodology you mentioned. Thanks again for the guidance!
To insert these types of shading (also three-dimensional in thickness) into EnergyPlus, you must create a BSDF file with GenBSDF and use Complex Fenestration. This way you have a very precise thermal response of the shading of the gap and the glazing as a function of the incidence of the solar angle.
