Shading control with variable transmittance schedule

asked 2020-12-06 16:31:31 -0500

Ammar De's avatar

updated 2021-12-21 19:45:05 -0500

Update I am updating this question since I did the test again using the latest version of EnergyPlus (V9.6).

I am investigating a simple concept on the impact of dynamic shading on buildings thermal loads using energyplus. I am using the Shading:Zone:Detailed class to define my shading surfaces. What I need to do is simply to deploy the shade during summer and remove it during winter.

To test this, I considered 5 scenarios:

  • a) No shading surface at all,
  • b) fixed shade with no transmittance schedule,
  • c) fixed shade with transmittance schedule = 1,
  • d) fixed shade with transmittance schedule = 0,
  • e) shade with seasonal transmittance schedule (i.e. sch = 1 in winter and sch = 0 in summer).

My analysis showed that cases (b) and (d), and cases (a) and (c) are exactly matching. When I apply case (e) the results are higher in heating energy compared to case (c) and lower in in cooling energy compared to case (d) (about 4% difference).

I realized that the reason could be due to the "DetailedSkyDiffuseModeling" algorithm option that is enforced when the transmittance schedule varies, and thus considered "DetailedSkyDiffuseModeling" and "updating frequency = 1" for all the cases.

I also tried to use EMS to vary the transmittance schedule (overriding a schedule), I can see that the schedule values are changing (by reporting the new schedule) but for the results the program ended up using the orignal schedule assigned in the Shading:Zone:Detailed class.

I came across this relevant issue and this on GitHub and looked at the comments by @Archmage and @JasonGlazer but I am not sure if the issue is already resolved? and if there is any workaround!

Thank you!

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Hi Ammar, I have a similar issue. Have you managed to solve the problem? Thanks, Berrak

Berrak's avatar Berrak  ( 2022-11-28 10:49:18 -0500 )edit

Not really, I submitted a ticket to the energyplus support but haven't heard from them yet. You can upvote the post, hoping it grabs someone's attention. I can see that simplified shading is getting some updates.

Ammar De's avatar Ammar De  ( 2022-12-13 19:41:28 -0500 )edit

Hi Ammar,

Thank you so much for your reply. I have also performed the simulations as you did. But, in my case, 'a' and 'c' are not matching. I figured this out because of the long-wave radiation that the shades are not transparent. link text

Could you please help me with this? Is there anything that is not opaque to long-wave radiation? How could you manage to remove the long-wave radiation and make the shades fully transparent?

Berrak's avatar Berrak  ( 2022-12-16 03:18:26 -0500 )edit