Dynamically controlled exterior shading device

asked 2017-07-18 03:55:33 -0500

NirajP gravatar image

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

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Just to provide a bit more information if it will help, please see link below for the code/script of the EMS program:

link text

NirajP gravatar image NirajP  ( 2017-07-19 21:51:33 -0500 )edit

Hello @NirajP. Did you have any luck yet? I am experiencing the same problem.

BBel gravatar image BBel  ( 2017-11-04 05:15:59 -0500 )edit

Hi @BBel, no I never got an answer to this although I suspect that shading screen with component blocks are only updated everytime the shadowing calculations are updated (every 20 days). I ended up just setting up a seasonal transmittance profile and guessing what the transmittance will be. I'm not happy about it but thats the only way I could figure it.

NirajP gravatar image NirajP  ( 2017-11-07 17:48:23 -0500 )edit

@NirajP If it is the shadowing calculation frequency what is causing your problem than switching the calculation method to TimestepFrequency should solve your problem.

Samuel de Vries gravatar image Samuel de Vries  ( 2018-02-28 01:42:33 -0500 )edit