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# How to Model switchable glazing (both U-Value and SHGC) using EMS in E+?

Hi all,

I was wondering if anyone could assist me with a research modeling problem (as a part of my PhD research) that I'm struggling with. Actually, I'm trying to model a single pane window: WindowMaterial:SimpleGlazingSystem.

However, I need to have this window modeled dynamically, in terms of U-Value and SHGC. More detailed, I want to model four different setups with this window including low U, low SHGC – low U, high SHGC – high U, low SHGC, high U, high SHGC. Meanwhile, I've already tried to follow Application Guide for EMS: Example 13. Surface Construction Actuator for Thermochromic Window as well as Application Guide for EMS: Example 6. Window Shade Control. Furthermore, I already visited the relevant posts on UnmetHours including How can I model Electrochromic glazing that switch between 4 mode?, Model dynamic electrochromic glazing in EnergyPlus, Errors using EMS on E+ to simulate dynamic insulation, and How do I model electrochromic glazing in Energyplus in order to getting continuesly dim ?

Having all said, I'm still struggling with this type of modeling, as basically my research problem is a combination of both dynamic U-Value (where I should use EMS to model a dynamic U-value) and switchable electrochromic (where I'm supposed to model different setups for WindowMaterialGlazing). In other words, I was wondering if I could model my four abovementioned setups as showed in the following screenshot

If this approach sounds correct, I was wondering if anyone could do me a favor and verify the steps that I should take with EMS, as follows:

1. Define in Class List EnergyManagementSystem:Sensor Tin and Tout as sensors for EMS
2. Define EnergyManagementSystem:Actuator - for the surfaces which have the dynamic insulation elements
3. Define EnergyManagementSystem:ProgramCalling Manager
4. Define EnergyManagementSystem:Program
5. Define EnergyManagementSystem:ConstructionIndexVariable

It would be my great pleasure if you could please let me know by any potential missing steps.

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Yes, your approach looks correct. I should note that the 4 simple glazing systems in your screenshot have different U-values and SHGC values, but they all have the same visible transmittance of 80%. If you want them to all resemble mostly-clear windows that don't change their level of tinting, then this is fine. In order to have these simple glazing systems defined as window assemblies, you will also need to create 4 Construction objects. Normally, these reference multiple material layers to define the assembly. In this case, they will only reference one material layer -- the simple glazing system.

1. Define in Class List EnergyManagementSystem:Sensor Tin and Tout as sensors for EMS

Yes, each EMS:Sensor would represent a unique temperature reading.

2. Define EnergyManagementSystem:Actuator - for the surfaces which have the dynamic insulation elements

Yes, specifically the Construction State control type and Surface actuator.

3. Define EnergyManagementSystem:ProgramCalling Manager

Yes, likely with program calling point "BeginTimestepBeforePredictor" so that the window change will impact the zone HVAC load calculations within the same timestep.

4. Define EnergyManagementSystem:Program

Yes, very similar to the EMS Example 13 you linked to.

5. Define EnergyManagementSystem:ConstructionIndexVariable

Yes, one EMS:ConstructionIndexVariable for each window assembly (so 4 total). Each of these references a Construction object for the given window assembly you want to apply in that situation defined by your EMS:Program.

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Aaron,

Thank you so much for getting back to my inquiry and for confirming my approach. Like always, you clarified in detail, which is super helpful to me and I truly appreciate it!

( 2020-07-30 11:52:11 -0600 )edit