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Dynamically controlled exterior shading device

Hi All,

I am attempting to model a building with an external perforated screen for shading. The screen is also operable in some location which allows it to be opened for daylight and passive solar gains when heating is required.

I am using DesignBuilder v5.0.3.007 and have modelled the screen as a component block. I believe that this gets translated into EnergyPlus as a Shading:Building:Detailed construction. I am attempting to dynamically control the transmittance of the screening by using EMS to increase the transmittance of the screen (i.e. "open the screens") when heating is required.

I am however getting a result that is not any different from having a fixed transmittance value for the screen. I know from the output:variable reporting that the EMS code is working so the problem appears to lie in the period with which shading is calculated. Does the effect of the DesignBuilder Component block / EnergyPlus Shading:Building:Detailed objects get updated each timestep or only when shadowing calculations are updated? (currently set at the default value of every 20 days).

If so, what would you recommend for modelling the above scenario?

Thanks in advance, Niraj