Hello bldg-sim community!

My name is Alex and I am a graduate student at City College of New York.
If possible I would like to ask you about EnergyPlus (EP) and the weather
file inter-work.

By reading the EP manual I understood that EP only uses *dirnorrad *(direct
normal radiation), *difhorrad *(diffuse horizontal radiation) and
*horirsky* (horizontal_infrared_radiation_intensity_from_sky)
to handle all calculations.

Why EP has this specific 'horirsky' (only IR spectrum) since EP already has
the 'dirnorrad' and 'difhorrad' inputs; that both include the whole EM
spectrum?

Thank you in advance.

Best,
Alex