List of HOY for solar analysis


I am in the midst of trying to resolve a workflow that is needed for my M.Arch thesis work.

Essentially, I have a list of HOY values that I would like to analyze for solar radiation. They do not necessarily bracket into a neat period between two dates.However, I would like to know the cumulative solar effect during their values on a facade surface by using LB’s solar radiation analysis component.

Conceptually it would seem I need a way to apply the list of HOY values I have to the GENCummulative sky component, or EPW import, as a sort of filter to extract which specified data points to be utilized for the solar analysis. This would be similar to editing a weather file than only analyzing the data points that exist in the file. This could be an option, but I am seeking something a little more automated;particularly since the HOY list is operating from a basic sorting criteria.The sorting criteria is intended to swap out weather files to obtain alternate results based on differing climates with relative ease.

Fundamentally, I do not know if there is a way to get around the limitation of the solar analysis component of using a date range or singular HOY. While also unclear how to filter out undesired values using HOY as a criteria when utilizing the sky matrix components.

Included is a crude sketch diagram of what I am trying to achieve.

Any help would be much appreciated!

Thank you,


There is an indirect way to solve this problem. If you are interested in excluding certain hours from the Gencumulativesky calculation, you can simply replace the existing radiation values for those hours with zeros.

Yes. Thank you for the suggestion. I was thinking along a similar line if it came down to it.

How would you suggest replacing the values to zero from a workflow perspective? It would be ideal to create a modify/replace routine within the GH environment. But I don’t know how to achieve that working with the Ladybug components. Perhaps you do and can enlighten me. I’m really trying to avoid altering the weather file outside of the GH environment. But is certainly an option; just not preferred.


I had created a work-around for this a few months ago. It might meet your requirement as well.

This is a skydome for the entire year.

The image below shows a skydome created with discrete hours (in this case, 9AM on everyday of the year):

The ghfile and the csv file for the calculations are attached.

(Just remember that this was a hack and I can’t guarantee that it will work properly on your system ! I am not sure if Honeybee has a native way of addressing this issue. I think Mostapha, Chris or Abraham might have a better solution. ) (447 KB)
9.csv (2.09 KB)

After a bit of preliminary testing, your python component appears to be working flawlessly for me. Many thanks! Truly indebted for your time and sharing of resources.

Dustin and Sarith,

The method of knocking out the values that you don’t want from the epw file definitely does the trick and I think that this is the only way that you can run a Honeybee radiation simulation with a custom set of HOYs.

I just wanted to note that, if you are only doing a Ladybug radiation simulation, you can leave the EPW file as it is and use a few native GH components to perform the cumulative sky operation operation like so:

See attached GH file for a working example.

-Chris (456 KB)


Your solution might probably be more stable than mine as my script requires getting inside the ladybug folder and deleting files.

                ladybugFolder = sc.sticky['Ladybug_DefaultFolder']<br/>                    existingEpwFolder = os.path.join(ladybugFolder,possibleFolderPath)<br/>                    if os.path.exists(existingEpwFolder):<br/>                        shutil.rmtree(existingEpwFolder)

My knowledge about the workings of Grasshopper components is pretty shaky and that’s why I end up writing my own scripts most of the time.

On a somewhat related note, is there any use-case (or Hydra/gh files) for the Honeybee_Generate Cumulative Sky component. I tried rendering an image with it and got an exception stating that it should be used for radiation analysis only. Is there a way that I can use that component with Radiance and ray-tracing inside Honeybee?


You can find an example file for a Honeybee Radiation study here:…;

Your exception was because you have to set the study type to Radiation and not the default Illuminance.


Thanks !

Thanks for the note Chris! Really appreciate it.

Considering I will need HB capabilities as well, knocking out values will likely be best. But really good to know how to achieve the same natively in GH.