Radiation calculation problem

Hello Mostafa,

I am using the Radiation analysis component. The result is always 0

and I have noticed that the output of the GenCumulativeSky component,

the GenCumSkyResult is always 0 in all the items. The epw weather file and

the GenCumulativeSky.exe are working properly. Can you imagine some issue?

I attach an image of the definition. As you can see from the Panel attached to the

genCumSkyResult output all the items are 0 (up to the 25th line is visible but also

all the others are). The report output says that “There were 3 sun up hours in this climate file”, is it ok? Thank you.



It might be because the radiation is 0 during the time that you are running the study? As far as I can see it is Manila Philippines. I don’t know about the climate in Philippines that much. Did you try to draw the sunPath for the same time and overlay the radiation on top of it? You’ll be able to see what is the sky condition at that time.

Hope it helps,


For the next release I’ll graft the output for each test surface so you can run it all using one component and get the result for each individual surface.

Hello Mostapha,

the period you can see from the screenshot.It is from 21 April 12:00 to 21 June 13:00. I don’t think therer is something wrong there, isn’t it? It gave me the same result also with Rome epw weather file. Thank you.



Mostapha, you mean that the calculation goes wrong because I am using three Solar Radiation at the same time? Anyway it’s strange that the GenCumSkyResult output returs always 0 in all the items.

Hi Francesco! Do you want to upload the definition or email it to me so I can take a look.

I didn’t mean that. Sorry if I wasn’t clear. The result will be the same regardless of the number of the components… You are right that the result form GenCumulative sky is strange.

Hi Francesco,

I had similar problem. If the geometry you are trying to use for analysis is a surface then you should give it some thickness or turn that into a solid. It worked for me. Hope this helps.

Hi Devang! I assume it should be a normal direction problem in your case. You could only flip the surface to solve the problem. In this case the result of the genCumulativeSky causes the 0 result.

Francesco! I received the file. I’ll check it and get back to you as soon as I get a chance.

Hi Mostapha, Since I was running daylight simulation with diva with the same geometry, First thing I made sure was that the surface normals were pointed in right direction. However, giving some thickness to geometry easily solved my problem.


Interesting! Then could it be because all the points were receiving the same amount of radiation and so they were all the same color (blue)?

I don’t think that was the problem. I also checked the total radiation value in KWh. It was 0.

If that is the case then you may have found a bug. I’ll be happy to take a look.

You know better Mostapha, but this happened with me twice. So now I have found a way around it by extruding the surface a little bit.

One of my classmate also had the same problem. She had an outer shell of building, which was essentially a surface, and she was trying to perform radiation analysis with it. I recommended her to make a closed solid. It worked perfectly in her case too.


It is good to know that extrusion solves the problem, but if it happened to you again please send me the file so I can find the cause. Thanks.


Sure. I will do that.