Radiation Analysis Incorrect Result


Recently I started adventure with Grasshopper and its modules. Untill i tried to perform radiation analysis everything was going quite smooth. But on this point I am struggling for some time. Results of calculations are incorrect and this is why I decided to ask for help in solving this issue.

I tried to find the answer on Rhino forum, but @Wim suggested to post this on Ladybug component due to lack of connections with Rhino and involve @Mostapha. So here I am! :slight_smile:

But let’s start with the details:

  1. Purpose - I want to visualize the distribution of solar radiation on uneven surface obtained from aerial survey.

  2. Object - imported to Rhino as .dxf contours, patched to form of surface and trimmed.

  3. Problem – While I was able to correctly position the sunpath, or radiation rose on the imported geometry, it was not possible to properly visualize the radiation distribution on it.

Since the surveyed plot is located in Poland, I used an .epw file for nearest town and expected values provided by i.e. Solargis. And this is where the problem lies…

Values calculated and displayed by the algorithms are incorrect. Numbers visible on the graphic below were calculated for entire year.

I’ve check everything: orientation, dimensions, location from epw for errors. File and rest of it is correct.

Even more curious thing – when I created simple geometry made of boxes and cylinders, values returned to proper numbers…

Can anybody of You help me with solving this?

Original Rhino forum link: https://discourse.mcneel.com/t/problem-with-geometry-real-life-terrain-vs-rhino-and-grasshopper/47580

Geometry file in the appendix.plot.3dm (277.2 KB)

Hi @proteus,
Please flip the surface and it should work fine. It is recommended to check surface normals for the analysis geometry. They should point outwards.

Radiation.gh (561.9 KB)

Thanks @devang !

Will check and revert whether it work as it should.

Is there some kind a tutorial explaining how this and other analysis should be done, contaning use cases and optimal parameters, hints etc?

I am a total newbie in this aspect, just starting to discover the whole Zoo and want to learn as much as possible…

I believe you should start with this series from @chris. Good luck with your studies!

Hi @proteus, Thank you for posting your question here. In case @devang’s reply is the correct answer please mark it as solved! Thanks.

Thanks for mentioning this @mostapha. Devang’s input solved the issue.
BTW: it is an honour for me to have You involved into discussion. I’ve seen the whole series You made for Grasshopper and Ladybug. Making those modules was a great idea!

7 posts were split to a new topic: How does Ladybug radiation analysis caclulates the results for a surface