Unrealistically high total sunlight hours


i am running a sunlight analysis on 2 surfaces with some context geometry and im getting a crazy total number of direct sunlight. The number im getting out of the component directly is 16,213 average hours of direct sunlight, and the analysis period is set for a whole year?

i am confused bcs the number shouldn’t exceed about 4000 hours… since 24*364.25 = 8742 total hours per year - say for example we get 12 hours of sunlight a year so that cuts it to 4371 hours of sun being out, then accounting for shorter days so like 4000 hours.

i tried running the tests on the surfaces individually but the numbers were still higher than they should be. Is there something that I am not understanding about the component’s outputs?

please help


@talalam ,

We would need more infromation in order to be able to help you. For example, are you using Ladybug Legacy or Honeybee[+]? Also what is the timestep of your calculation?

Hi @chris ,

Thanks for your response, I believe I am using Ladybug Legacy. The timestep is set at default and I believe the value is 1… I have uploaded my script and the link to the EPW

sunlighthours test.gh (850.7 KB)


Thanks in advance

I don’t see anything wrong here. Please check the legend in the rhino space. That should help you understand which point receives how much of the sunlight hours out of the 4378 hours you have selected for the study.


thanks for your response, i just chose 4371 hours as an arbitrary number that seems reasonable based on the calculation i made above.

i am getting a massive value from the component of 3.74 million hours of sunlight for the one year i chose as my analysis period… that is not right so i need help in debugging…why is the component giving me such a high value for the total sunlight hours if nothing seems to be wrong with the script?


Some quick thoughts

  1. Just looking to your screenshot, I noticed this:
    Ladybug_import epw output _location is connected to Ladybug_Radiation analysis input north_
    I suppose that this connection provides two (supposed wrong) different orientation to the model, therefore Ladybug has to carry two analysis. The cumulative results should be doubled (result 1 + result 2).
  2. why are you adding total radiation [kWh/sqm] with total sunlight hours [h]?
  3. Regarding the totalSunlighthours output, looks like there’s something wrong. Check sunlighthoursResult output to see sunlighthours for each analysis point.
    Have a check!

You can see the number of sunlight hours received at each point like so.
The totalSunlightHours output is (area of a mesh face * the number of sunlight hours received at that mesh face). For some reason this number does not add up in your case due to the geometry. I am looking further into that.


thanks for pointing that out! never caught it… i was running some evolutionary algorithms on the geometry which is why i added the radiation and sunlight hours as I was trying to maximize both - discard that part…
i cant seem to figure out the problem with the sunlight hours but i will try rebuilding the script and hoping that will fix it…

Please do look into that - i believe the undulating geometry might be causing the issue with the calculations but please let me know if you can figure it out…

thanks again

I see now. Since you are doing an optimisation exercise you’re interested in the totalsunlightHours. I will dig deeper.

I might be wrong here but I think the totalSunlightHours is sum of all the sun hour received on each mesh face (disregard the mesh area).