Problem with Drangonfly and Urban Weather Generator

Hi all,

First of all thank you for the amazing tools that you provide to the comunity!

I am facing problems whit Dragonfly and Urban Weather Generator component. I get some error messages from the calculation interface and from the component itself. How can i solve this issues?

The Urban Weather Generator component says this :“1. Solution exception:Impossibile trovare il file ‘c:\ladybug\unnamed\UWG\unnamed_DEU_Bremen.102240_IWEC.epw’.”

Thank you in advance.



Hi Angelo,

Thanks for using Dragonfly and I think this results from having wall/roof construction materials that are thinner than 1 cm. Having materials this thin messes up the UWG’s heat flow calculation through the construction and I would recommend removing such thin materials as they usually have a negligible effect on the results. If you upload your Dragonfly GH file, I can check whether this is the case.

I know the new UWG has a check for construction materials this thin and, once I upgrade Dragonfly to this new version, you should not have to worry about this type of error again.


Hi Chris,

Thanks for your fast reply!

I was using your file to test the Dragonfly workflow that i should use for an upcoming research. I checked the file and seems that there aren’t such a thinner materials. Anyway, i upload the GH file for double checking the issue.

Thank you again.

UWG_Outdoor (1.13 MB)


I’m going to need some more time to look at this and I’ll hopefully get back to you tonight once I can sit down for a while.


Hi Chris,

Don’t worry about that. Take your time and thank you again for helping me to solve the problem.



I was able to run the GH file that you uploaded with the Bremen EPW on my machine at home:

I am going to try uninstalling / reinstalling my UWG to see if something could be messing up in the setup as I know others have had issues as well.



I found out what the error was. Drangonfly_Dragonfly downloads some supporting UWG files in the background to help run the simulation and it seems that github changed its conventions for how to download such supporting files from repositories. I have fixed this with these commits to the UWG:…

To get everything fixed on your machine, you should navigate to C:\ladybug and delete the UWG folder there. Next, load up the attached script or the updated Hydra example file:…

Then everything should run fine. Let me know if this fixes everything on your end.

-Chris (1.14 MB)


Thank you for your support! Now, everything work fine!

All the best,


Gad to hear it!