Im trying to verify solar radiation of ground surface which is reflected from the other buildings with “Run Daylight Simulation” component and “annualSimulation” component.

To analyze reflected solar radiation, I wanna isolate direct radiation from total radiation.

I tried to modify the epw file.

I changed numerical values of Global Horizontal Radiation when there is no Diffuse Horizontal Radiation, and inputed zero into Diffuse Horizontal Radiation value.

But the result was all zero.

I used following formula.

Global Horizontal Radiation(Direct Horizontal Radiation) = Direct Normal Radiation*sin(solar altitude)

Please let me know how to evaluate only direct radiation.

I’m not sure if you’re trying to find the direct radiation as the title of your question says or the amount which is reflected from other buildings which is what I understand from the first paragraph.

In any case, if you apply a fully black material to buildings and set ab to 0 then you will get only direct radiation as radiance won’t calculate any of the ambient bounces.

Now you can subtract the values of the analysis with normal setting from this one to find the reflected values.