Interior roller shades parameters

Hi there,

I am carrying out a shoebox energy model with a south orientation about an office building in Greece. The idea is to account for the interior roller shades in the calculation of the lighting (with daylight harvesting) and cooling. I am having a hard time finding parameters of realistic blinds values (Ts, Rs) that are available in the market to use as inputs in my simulation. So far the most realistic values I found are the total fenestration (window + interior roller shades) SHGC values from ASHRAE handbook of fundamentals, where an attenuation coefficient is being considered accounting for the roller shades effect. However, I don’t know how to apply a schedule or automatic control to this SHGC with roller shades and without roller shades. I believed there must be another way out to do this and obtain realistic results. If I am not mistaken for high-performance windows expecting a solar heat reduction of more than 15% by adding internal roller shades is not realistic.
Does anyone face this issue before?
Do you figure out another way?
Is it possible to convert IAC values into Solar transmittance as an input in the shade material HB component? any rule of thumb?