Hi everyone,

I’m Cristina and I’m new with Honeybee,Ladybug and Dragonfly. I’m trying to customize .epw file with UWG generator. I’ve followed Hydra example and it gives the following message of error when I run it. At the end of the running, it generates new file epw with changes. Is it reliable as result, even if it gives a message of FATALE ERROR?
I post a screenshot and file .gh

UWG workflow.gh (1.4 MB)

Thanks to everyone will try to fix the problem!

Dragonfly 0.0.3 and Urban Weather Generator 5.0 Released!

@cristina_mg, unfortunately this is a known bug that we are working on solving:

It’s tied to the calculation of heat flux through the construction assemblies. If there’s a very thin material layer, or large increase in the solar flux from one hour to the next, then the heat flux calculation becomes unstable and throws this error.

So, if the error was tied to your EP constructions, we could have solved the problem, Unfortunately I checked your EP constructions, and they aren’t the problem, it’s the weather file itself which is creating the larger heat flux to cause this error… which means the only way to solve it is a lot more complicated, most likely changing the heat flux calculation. This is something we will try and solve, hopefully soon after the next Dragonfly release.


I just wanted to confirm that @SaeranVasanthakumar is right on the nose and that the next release of Dragonfly should be pretty soon (probably within a couple of weeks). This will run on the python UWG that Saeran just finished and, since it it inside python it will be a lot easier for us to fix bugs like this.


Thanks a lot for your answers! I hope that the problem will be fixed soon, meanwhile I have decided to work directly with Matlab to resolve the problem.

Thanks very much for your work,



@cristina_mg great! Let us know if you can get it to work!


Yes it works! I have only to study how to customize constructions with Matlab, but most important thing is that now I have a customized epw file, thanks a lot! :slight_smile:

Now, doing the energy simulation to study how outdoor and indoor comfort change according to constructions zone, I have set a grid for the ground that I have modelled as in the script Outdoor_Microclimate_Map from Hydra, but simulation doesn’t work. I have tried to run it without this setting for the ground and it works fine, so I think that the problem is relative to ground zone.

I’m attaching 3d model and script, when you have time, could someone tell me where is the error? (If it is necessary, I’ll open a new topic)

Outdoor_Indoor_Comfort 23052018.gh (1.4 MB)
Model Outdoor_indoor_comfort 23052018.3dm (8.9 MB)

Reference script:
Outdoor_Microclimate_Map.gh (714.2 KB)

Thanks very much,



@cristina_mg, I’m glad you got it to work! Are you using the .m, .xlsx or .xml file input method in Matlab?

I found a similar situation with another UWG FATAL ERROR here (RunUWG 0.0.02 is not running), that is, the compiled Matlab version throwing an error, but a similar set of inputs works fine with the .m method.

The fact that Matlab manages to perform without throwing the error, while the compiled version does, indicates that: there may be a bug in the compiled software, there may be a bug in the .xml input method, or we are introducing the bug (i.e high heat flux) through the customization of materials or geometry when we generate the .xml.

So let me know if you are using the .m, .xlsx or .xml file input method in Matlab, that’ll go a long way to start figuring out this bug!

As for the outdoor and indoor comfort zone problem, you should start a new topic to discuss it.


Hi @SaeranVasanthakumar! I’ve used an .xml file, in which I have set every parameters, except for customized wall constructions. It works fortunately and if I have time I’ll try to set also walls. :slight_smile:

Ok thanks very much, I’ll open a new topic! :slight_smile: