Direct answer:
Yes, they do.
They will reduce the direct sun light on your window, consequently can reduce the heat in the room working as an shading element.
The complex:
Depends a lot of the bioclimatic strategy you needs to apply and needs to analyse the lots’ climate. Example: Using the sunligh to heat a closed glassed room to store heat in your home.
You can use the psychometric chart as reference to check what yours project recommended strategy.
Fortunately ladybug can build this chat to you.
As far you are giving more and more info to your simulation you can achieve more realistic results.
When I have a free time, I will test the joined brep to test the corned geometries. Sorry.