Hi. We are trying to conduct daylighting/PV/energy balance analysis of a reference office using a glazing with special micro-optics that treat very differently direct and diffuse light. We will need to split simulations in direct and diffuse components, and then merge results. We would assign different BSDF files to the component under direct sunlight and diffuse light.
PD: This component is actively tracking sun direct light, so the actual BSDF changes continuously as a function of sunlight’s angle of incidence. This would require a huge amount of .xml BSDF files and switch between them dynamically, which I assume would be too computing intensive. Furthermore, the BSDF patches would need very fine around the sun (tensor tree), which would make a ton of data.
I am not sure that DGP is a meaningful metric if you look at the diffuse and direct luminance separately. My intuition tells me that the whole visual contrast calculation for DGP is going to be wrong like this.
Still, if you want to look at luminance or illuminance separately for any point-in-time study, you should be able to accomplish this by using the HB Custom Sky component, which allows you to input custom values for direct vs diffuse irradiance.
Thank you for your response, Chris. I thought HB Custom Sky would create complete sky distributions following the direct/diffuse ratio set as input (e.g, a grey overcast day if I set direct irradiance to zero). Would not it be the case?
This is why the HB Visualize Sky component is very useful. You can see that the HB Custom Sky generally reflects the input direct and diffuse illuminance.
So you can do a simulation of the direct and uniform diffuse sun separately.
Alternatively, if you want the diffuse irradiance to be distributed in a manner that is consistent with a sunny sky, this is why there is a “sunny without sun” option on the HB CIE Standard Sky.
