How do you define a single radiance material to approximately represent multiple materials of an urban context —surrounding the building which is the subject of simulation?
For instance, imagine that there are some buildings in the surrounding area. All of them have concrete facades with 40% windows (glazing ratio). Is it possible to define and assign just one radiance material to them?
I would recommend using the available information in that case. You should use the out-reflectance value of the glass (generally found in the vendor specification). If you know the opaque surfaces are concrete then you can look for a radiance material for the same on the website I shared.