shading devices effects on buildings

[m_stellab]

Hi,
I want to simulate the shading effects of lamellae on the facade of a building. How can I model them without using pv panels or rooms? For example, using only surfaces. I also want to attribute to this surface a specific material in order to understand the effects of colour and of material's properties.
What parameter in Vista could I use to understand the effects of the shading? I cannot use the solar gain because the building behind the lamellae is not glazed.
Thank you.