Component to evaluate the Direct Normal Radiation in LBT

Dear community,

out from a weather measurement data, I don’t have the “Direct Normal Radiation” values but only the Direct solar Irradiance to a horizontal surface values and the diffuse Horizontal Radiation, togethet with others climate data.
There is a component to evaluate the Direct_normal_radiation with the right formula, not considering the HBDeconstructWea component? I found the component only for the DirSolarRad evaluation.

Same thing for the Direct, Normal and global illuminance, where I have only the Horizontal Infrared radiation. There is a component with the right formula, to evaluate this parameters, without having to use the DF Luminous Efficacy component together with the Zhang-Huang solar model?


Hello Liam,

having the Direct Solar Radiation value out from your Weather Data for each hour of the year, dividing that parameter by the cosine of the sun zenith angle, (that you can get from the Sun Altitude output of the SunPath Component. Zenith Angle= 90° - Sun Altitude), you should have the Direct Normal Irradiation. But is better to ask a professor of this sector.
Dear @AbrahamYezioro, excuse me if I bother you into this question, can you advise if is the right method?
Is correct that the Direct Normal Radiation can be calculated DNI= Direct Solar Radiation / cos of the Sun Zenith Angle?

Hope it helps


Hi @LaFleur ,
Sounds ok for me …


That’s the right formula, @LaFleur ! It’s just some simple trigonometry. And you can use the LB Sunpath to give you the solar altitudes (or the zenith) for each hour, @LiamRuvio .

FYI, once you have the direct normal and diffuse horizontal radiation, you can use it to construct a Wea object inside a GHPython component, using the Wea constructor you see here in the SDK. Then, you can pass the Wea object to the “DF Luminous Efficacy” component to get illuminance. Granted, you should also keep in mind that these EPW illuminance values aren’t used by either EnergyPlus or Radiance. So it’s also totally fine just to leave them blank.

Thanks @LaFleur you were really very kind.

@chris thanks for the tips.

Best regards