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[EnergyPlus_Support] daylight illuminance calculation
Hello everyone:
I feel confused with daylight illuminance calculation.
(1) Is that right: Sky Luminance Distributions are just used to calculate the luminance of the sky and DO NOT include the solar when used? In this sense, For Direct Component of Interior Daylight Illuminance (From Daylight Factor calculation part in Engineering Reference ), the luminance of the window element as seen from the reference point should include both of sky (from luminance distributions) and solar (how to calculate??) ?
(2) In the weather file, Diffuse Radiation, Direct Normal Radiation, and Global Radiation are provided, but according to the calculation method of Daylight Illuminance, all of the calculations for sky clearness and brightness, and horizontal illuminance are from irradiance, which is different from Radiance (while its unit seems right). Is there any place in the reference document to introduce the conversion between them?
(3) In the Engineering Reference, in the part of Sky Radiance Model (Climate, Sky and Solar/Shading Calculations Part), it is said that "the diffuse sky irradiance on a surface is given by: AnisoSkyMultiplier(surface) * DiffuseSolarIrradiance". In the weather file there is diffuse horizontal radiation. Is this different from the DiffuseSolarIrradiance? I read the Engineering Ref but still very confused with the process of calculating the irradiance, radiance in EnergyPlus.
Thank you in advance.
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