Small difference in results between radiation analysis and Real time radiation analysis


#1

Hey,
I was doing a simple radiation result using Ladybug radiation component and real time radiation analysis. I compared the result from the radiation analysis (I looked at radiation result not total radiation) for one day (151 w/m2 when i converted it from kWh/m2), and then ran a full year result and checked the results on the same day using the real time radiation analysis and got a bot higher results (155 w/m2). Is there an explanation for that?
I also noticed that I was receiving a direct component in the radiation result at one hour, however when looking at a simple shadow analysis in Rhino the neighboring building was shading this window at this hour. My assumption is that this is because of the sky division and accuracy, that the sun patch might be big in the sky division and therefore the window is receiving some direct sunlight even though it should not at all. is there another explanation for that?

Thanks in advance,


#2

For the first part we will need a sample file to debug.

The ray is shoot from the center of the mesh face to the center of each sky patch. You can get the vectors from Sky component if you want to test them yourself.


#3

Hey,
Thanks for the response, I am attaching a simple file, the day that I was testing 21st of May at 11, using Stockholm-Bromma weather file will give the numbers I have mentioned in the first post,

Debug.gh (545.1 KB)

I got the vectors but I was not sure what is the best way to visualize it with respect to the window, can you help me with that as well?

Thanka alot,


#4

Attached a workflow i suggest for your case: Calculate the skyMtx for the whole year and then derive the individual dates with the RTRadiationAnalysis component.
I know i don’t anser your question (why the individual date radiation results doesn’t match the RTRadiationAnalysis’s). Tried many things to check and myself don’t have a clear answer.
Anyway, you can also find the vector projected from the center of the checked surface to the center of the sky patch relevant to the date you asked.

-A.
Debug_AY.gh (568.8 KB)