Weather file shows beam radiation when ladybug predicts sun is below horizon?

Hello all,

I’ve stumbled across an unusual situation where for certain hours of the year the LB Sunpath component predicts that the sun is below the horizon even though the associated climate file shows that beam radiation is registering. In the definition attached I’ve found that there are 138 separate hours in the year when beam radiation is recorded in the weather file and LB Sunpath predicts the sun is below the horizon. I’d be very grateful if anybody knows why this is happening.
Many thanks.

Radiation Recorded when Sun is Below (24.5 KB)

Hey @Rory, welcome to the forum!

I’ve only had a quick look at your script, but I suspect the reason is something to do with this thread:

All of the HOYs you’re reporting are in the morning, so maybe something like the sun is below the horizon at 7am, but then the epw records radiation for the period 7-8am…?


Thanks Charlie,
The thread you put me onto helped a lot.
If I understand correctly, for a given HOY Ladybug reports an instantaneous sun position (assumed to be at the start of hour) while epw data is reporting the average condition for that hour (calculated at the end of the hour).
For my purposes I have managed to resolve the issue by shifting the epw data forwards by one hour.
Thanks again,

1 Like