As noted in the descriptions of the fields used in the EPW (Auxiliary Programs document), no -- EnergyPlus does not use the sky cover values (nor the illuminance values) in calculating daylight illuminance. I believe it relies strictly on direct normal radiation and diffuse horizontal radiation in those calculations.
Sky cover values are only used to calculate the Horizontal IR from sky (if it is missing on the weather file). Horizontal IR from sky, I believe, is principally used in calculating the sky temperature.
At 08:26 AM 11/10/2009, Hu,Jia wrote:
Hello, all
I download newest weather file of Gainesville. The change is the "total sky cover", "Opaque Sky Cover", and "Horizontal Infrared Radiation Intensity from Sky".
But I use EP to run the simulation using the latest weather file and found the illuminance of the ref. point keeps the same as that using old weather file.
My question is whether EP use the "total sky cover", "Opaque Sky Cover" to calculate the illuminance of the reference point. If using, why my result did not change.
Thank you,
Jia
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