[Solved] ExportToOpenStudio vs runEnergySimulation - Results differences

Replies to This Discussion

Permalink Reply by Chris Mackey on October 4, 2016 at 6:56am

Abraham,

I know that there is a very small difference between how the two components write out the ideal air system.  Specifically, the E+ component uses a template system that is easy to add to the model but harder to size correctly.  The OpenStudio component writes out a full Ideal Air system that has more detail and is sized more robustly to handle the loads in extreme times.  It is possible that this may account for the difference.

Is this a simulation that you are running with the ideal air system?

If not, I don't know of any other major differences between the two except that the OpenStudio component has an implementation of daylight controls that shouldn't affect anything since it is turned off by default.  In this case of not having an ideal air system, upload the gh file (no matter how large) and we will get to the bottom of the difference.

-Chris

Permalink Reply by Abraham Yezioro on October 4, 2016 at 1:51pm

Hi Chris,

I checked a bit more thoroughly. This happens with both conditioned and unconditioned models.

I'm attaching the unconditioned example (needs the 3dm also. Sorry for not internalising).

Disable the solver before opening. It can take a while to run.

Also attached the IDF files created by each component. The differences are minimal ... if any, so i can't explain the differences.

Any thoughts?

Thanks,

-A.

Attachments:

• munot o - A1_Clean.3dm, 710 KB
• E+.idf, 253 KB
• munot o - A1 - 15.09.16 - ASHRAE-EU_AY_Updt.gh, 1.9 MB

Permalink Reply by Abraham Yezioro on October 4, 2016 at 1:52pm

And the OS idf file.

Attachments:

• OS.idf, 235 KB

Permalink Reply by Chris Mackey on October 7, 2016 at 3:32pm

Abraham,

It was just too difficult to test anything with your file but I was able to  replicate the issue with a smaller model and simpler GH file.  I got the OpenStudio component giving far worse comfort than the E+ component even though the average temperatures were similar:

It turns out that it was not the known difference in ideal air system between the components (swapping out the ideal air template into the OpenStudio file did not affect the results).  Rather, it was a bug in the OpenStudio component that was causing incorrect default constructions to be written for some of the surfaces.  I think your case wasn't affected as much because you are overriding a lot of the default constructions.  I fixed this bug here:

https://github.com/mostaphaRoudsari/Honeybee/commit/6b185b5c8b7d9b1...

And I now get results that match very closely.

Let me know if updating your components fixes your issue, Abraham.

-Chris

Permalink Reply by Abraham Yezioro on October 8, 2016 at 10:46am

Hi Chris,

Thanks. It looks good ... for your example. Unfortunately for mine the differences remain the same as in the original message. I mean, no changes with the updated component (6 October).

I tested the surfaces temperatures for both E+ and OS. there are differences of 1 degree in the minimal and 0.5 in the maximal scale of the legend for the typical weeks (hot and cold). As i said before, comparing both IDF files they are pretty much the same, except for the ScheduleTypeLimits, where the E+ writes 91 objects and the OS only 8-9. Also the OS writes some Schedule:Week:Daily and Schedule:Daily:Interval for Warehouses and they are used for the calculations. Needless to say that i defined for all zones MidriseApartment program.

Additionally, you are right. I defined almost any possible value, so practically no defaults were left to be used.

Last thing, I understand that both components run EnergyPlus 8.5 installed in the OpenStudio installation directory. I don't have installed 8.5 besides that. Is this right?

Any suggestions?

Thanks again,

-A.

Permalink Reply by Chris Mackey on October 8, 2016 at 3:35pm

Abraham,

The warehouse schedule difference sound suspicious (do you know where in your script these are being defined?)

If it's not this, then the only significant difference is the ideal air system.  Can you check with the new EIO component to see if the size of your ideal air system is very different for the two simulations.  This discussion includes an image of how to do this:

http://www.grasshopper3d.com/group/ladybug/forum/topics/heating-and...

You might just want to oversize both systems a lot (using EPSimPar) to ensure that all setpoints are always met.

-Chris

Permalink Reply by Abraham Yezioro on October 8, 2016 at 9:43pm

Hi Chris,

I don't define anywhere something related to Warehouses. I strictly defined each zone as MidriseApartment. You can see in this image where this is happening in the script:

As for the schedules, also this image shows where i'm defining/assigning all of them:

BTW, the warehouse stuff appears ONLY in the exportToOpenStudio option.

Finally, i'm not conditioning the zones. Explicitly i asked to set the isConditioned_ input in the HB_createHBZones to False. The discussion you mentioned approaches this differently oversizing the heating/Cooling so you never need the AC. The IDF created don't have any definition of IdealSystems, so i don't believe this is the problem. If you want to see the IDF files you can see them above (attached in a previous message).

Weird ...

Thanks,

-A.

Permalink Reply by Chris Mackey on October 9, 2016 at 9:14pm

Abraham,

I checked and the warehouse schedules are not being used at all even though they are being written (so that is not it). Much of the differences in the way the schedules are written seems to do with the fact that OS does not support CSV schedules and so we have to write these in after IDF translation.  I'm trying to test your GH file but I'm getting errors from the simulation:

This really seems to be too complex of a model for me to separate honeybee code issues from the energy modeling issues.

The best I can offer if you are able to run your model on your machine without errors is to try producing an energy balance graphicof the two models and see if there is one specific term that is out of order.  This will at least give us a place to start looking.

-Chris

Permalink Reply by Abraham Yezioro on October 9, 2016 at 11:29pm

Hi Chris,

So you gave me some homework and i did it :-)

There are differences, some of them big, specially with NaturalVentilation and Storage results:

And the summary of the differences are (i left only those that are significant):

As you see, naturalVentilation is giving higher loses in the OS option.

Attached also an excel with all the data. Maybe it will help.

Is this useful for debuging?

The error of the simulation is related to non-convex surfaces. Is severe but the simulation runs. I need to check where is (are) the bad surface and correct it.

-A.

Attachments:

• Compare_EnergyBalance.xlsx, 21 KB

Permalink Reply by Chris Mackey on October 16, 2016 at 11:20am

Abraham,

This is great and thank you for doing the homework :).  At least now we know now that the issue seems to be with the natural ventilation since the other terms are looking really similar.  The storage term is just computed as the remainder of the other terms (to make the energy balanced) so it is really only reflecting the difference in the natural ventilation between the two simulations.

Let me see if I can re-create this difference on a small scale and, hopefully, this will then fix your issue.

-Chris

Permalink Reply by Chris Mackey on October 16, 2016 at 11:54am

Abraham,

I unfortunately can't seem to replicate the error on a small scale.  I'm getting results that match perfectly:

-Chris

Attachments:

• TryToRecreateNatVentError.gh, 674 KB

Permalink Reply by Chris Mackey on October 16, 2016 at 11:58am

Abraham,

I took another look at your file and realized that you are also not setting up the nat vent component so well.  If you use the nat vent specifications that I have in the previous file that I attached, let me know if you get comparable results.

-Chris

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