No light sources found


I’m doing an annual daylight simulation on grasshopper using the epw file of Bolzano (Italy). When the analysis starts, it tells that no light source can be found. It happens also if I change the epw file. Can someone help me with this problem?



Hi Marta ,

It´s not an error , no light source- is for the interior lights , so unless you´re not running artificial lighting similation is not a problem, please refer to :…

Hi Peter, thanks for your answer!

Now I think I’ve done some other mistake. The simulation gives out that my daylight autonomy is lower than 0%, which is quite strange, also considering that I’ve no context around. I’m doing the simulation of a room with two windows, one on the east side and the other one exposed to south. I followed some simulations I’ve found on Hydra and I don’t really understand which could be the error.

I attach the .gh file of the simulation and a screenshot of the result of the room. Can you kindly give a look to it?

Thanks a lot for your help


occupancy.csv (197 KB) (648 KB)

Hi Marta,

It´s working for me (and for you the same way), your problem is the occupancy , try it with normal working hours 8:00 to 17:00 and you will see the difference.

I know you have a apartment house so the problem of low DA % is that people are never there when the sun is up, so therefore they need to use always artificial light.

Hi Peter,

the simulation runs in the right way using the occupancy file generated by honeybee. The apartment is used as an office, so I think that the problem was the way in which I created the occupancy file. So now I’m going to write the occupancy file in a better way than I did before…

Thank you