Honeybee and Ladybug skies for radiation analysis



I have a question about the different skies in HB and LB for a radiation analysis. I have seen some posts from other people asking similar questions, but I just want to make sure I understand everything correctly.

As far as I understand, LB and HB are using different functions of Radiance to model the sky. I am trying to compare these 3 components:

a. GenCumulativeSkyMtx, used for the LB radiation analysis that uses the gendaymtx function of Radiance.
b. genCumSky, used for the HB radiation analysis that uses the genCumulativeSky function, and
c. genClimateBasedSky, used for for the HB radiation analysis that uses the gendaylit function (am I right??)

My questions about this are:

#1 Are gendaylit and gendaymtx calculating the same thing?

#2 Is there a way to use the GenCumulativeSkyMtx component of LB for a HB radiation analysis? It seems that the output of that sky component cannot be used as input for the radiation analysis of HB. I would like to use something similar to the climate based sky but that only calculates result for a specific hour and I need an annual calculation. I thought to run it in a loop for the whole year, but that takes a very long time.

#3 If I understand it correctly, genCumulativeSky is less accurate than gendaymtx, so why did you use one for LB and the other for HB? I see at a previous post that you plan to change that (https://www.grasshopper3d.com/group/ladybug/forum/topics/the-difference-between-gencumulativeskymtx-and-gencumsky). Is this still the case?

Thank you very much for the help!!




No. gendaylit generates a continuous climate-base sky for a point-in-time. gendaymtx generates annual perez sky matrix which is not continuous. You can find the documentation for both of them here: https://www.radiance-online.org/learning/documentation/manual-pages

Yes. See Honeybee[+] radiation recipe. https://ladybug-tools.gitbooks.io/honeybee-primer/content/text/components/Annual_Radiation_Recipe.html

See my answer to question 2.


Thanks again for the help! :smiley:


Hi again! I am trying to use the HB+ annual radiation recipe that you suggested, but I am running into some problems.

First, I am trying to use the genCumulativeSkyMtx but it doesn’t seem to work with this analysis recipe. Am I doing something wrong? I replaced it with the HB + skyMatrix but I don’t understand what this is. :confused:

Then, the runDaylightAnalysis doesn’t work with this recipe. Should I use some other component from HB+?

Also, I don’t understand what are the recipe types “point in time”, “3phase”, “5phase”. Which one should I use? And last, the RADparametersGridBased seems to be overwritting the parameters I set. Can I avoid it somehow?

Thanks again for your help!! I am attaching my file. :slight_smile:

HB radiation analysis.gh (518.3 KB)


Honeybee and Honeybee[+] are two different plugins and don’t necessarily work together. See the sample file for annual radiation study on GitHub:

Point-in-time recipe is similar to grid-based recipe in Honeybee legacy plugin. See this post for 3-Phase and 5-Phase: An advanced tutorial for daylighting simulations They are considered advanced workflows and unless you really need them you should not be using them. There is a diagram in the referenced tutorial that shows when to use which method.

Thank you for sharing the file. You are using the component from Honeybee legacy plugin to set the parameters in Honeybee[+]. That won’t work. You should use the Honeybee[+] version of the component. Which is this one.

Finally please set up your profile picture! Thanks.


Great! I downloaded the example that you suggested (annual_radiation_grid_based) but I have a problem making it work with a weather file that is not downloaded from the Energy Plus website. The weather file has values for direct normal, diffuse horizontal and global horizontal radiation.

Can you maybe check what is the problem with it? It would be very helpful! :smiley:
It previously worked with Honeybee.
DNK_DRY2013 (Honeybee).epw (1.4 MB)


and what is that problem? It doesn’t run? The results are not as expected? …


It doesn’t run. :confused: I am getting this error message:

But when I am using another weather file from the Energy Plus website it runs. :confused:


Actually, I deleted the result folder and run it again and now the .ill file is no longer empty. So now it works. :slight_smile: