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Possible solution to the EnergyPlus' two shading devices on same window impossibility?

asked 2020-09-11 22:02:00 -0600

Mafalda Correia's avatar

updated 2020-09-15 13:09:37 -0600

Like many of you, I'm faced with the problem of wanting to assign two shading devices to the same window - an exterior shutter (shade) and an interior blind (operating on different conditions) - and finding it is not possible on EnergyPlus, even with EMS' shading control. The simplest way would be to just drop one device. In my case, I would place exterior blinds, but that's not ideal nor what I desire for my model - I want to use the shutters as "movable insulation", and the blinds to block radiation while still providing some daylighting when the occupants are home.

So I've thought of this: while specifying a window's shading control on EMS, would it be possible to include the second device's conditions that when met change the window construction to another one including (the window and) only the second device? (The construction would be called with ConstructionIndexVariable.) Stipulating the second one like this, EnergyPlus would still assume the correct placement of the device layer (since it is defined by order in Construction) and assume it as totally deployed (on), or not? And if it was a blind, it would simply be fixed at the slat angle defined on Material.

Would this cause conflicts with the window construction associated with the first device's WindowShadingControl? Maybe if the first one is defined as a separate device, not a construction with shading, no problems would arise? I haven't tested this since my script isn't complete yet. Would this produce no E+ internal problems and work in the desired manner?

If you know, please let me know. Thanks in advance.


According to which refers to @MJWitte's answer on about shading an internal window, my construction switch theory was right. And I think E+ performs correct optical and radiative assessments to extend this to external windows as well, since assigning a Construction with Shading is an option in WindowShadingControl and this method simply emulates that with EMS, so I conclude it must be a valid method for all openings.

So, shading devices can be changed by changing the whole window construction with EMS' Surface Construction State, solving the two devices on same window problem and the shading device on internal opening impossibility (which is also useful for me).

I used: as the primary device, the external shutter declared on WindowShadingControl (inserted as a separate device, not a construction), and as the secondary device the internal blinds constructions on EMS. I did it like this simply because I have more shutter conditions and I had already started writing the EMS Window Shading Control Control Status for the shutters, but this way the blinds are fixed at the slat angle defined on Material. I may change it to make the blinds block solar beam radiation and place the shutters with the EMS construction.

Below is a part of my EMS Program for the shading control. I use ... (more)

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I corrected my OpenFactor EMD code by including the availability schedules where needed. I still get a severe error only for the Constuction State-placed shutters on my sunroom's internal glazed doors. With that little part of the code included, I get a nasty 'Convergence error in SolveForWindowTemperatures' that I can't get rid of (I tried the tips of increasing the HVAC's minimum supply temperature and the 'convergence tolerance value' on Building).

Mafalda Correia's avatar Mafalda Correia  ( 2020-09-14 21:34:53 -0600 )edit
Mafalda Correia's avatar Mafalda Correia  ( 2020-09-16 07:24:50 -0600 )edit

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answered 2020-09-15 11:54:59 -0600

Mafalda Correia's avatar

updated 2020-09-15 12:11:46 -0600

Answer to the Availability Schedules question: I just found this post stating that the Availability Schedules get overridden as well as the control conditions, thus need to be checked in the EMS code. I would have been in great trouble if I hadn't found it.

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Asked: 2020-09-11 22:02:00 -0600

Seen: 1,650 times

Last updated: Sep 15 '20