Shading control with variable transmittance schedule

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

Ammar De gravatar image

updated 2020-12-07 08:30:06 -0500

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 as part of hipped roof overhangs. 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 and 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) are exactly matching, cases (a) and (c) are slightly different (0.1% and 0.4% difference in heating and cooling respectively). When I apply case (e) the results are 1.5% higher in heating energy compared to case (a) and 3% lower in in cooling energy compared to case (d).

I realized that the reason could be due to the "DetailedSkyDiffuseModeling" algorithm option that is enforced when the transmittance schedule varies, and thus the results may not be comparable. However, I tried to use the "DetailedSkyDiffuseModeling" algorithm for cases (c) and (d) but that didn't change the results from what it is (i.e. using "SimpleSkyDiffuseModeling" algorithm). I also tried to use EMS to vary the transmittance schedule, I can see that the schedule values are changing (by reporting the new schedule) but for the results the program ends up using the base 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. I am not sure if the issue is resolved? and is there any workaround? I am using energyplus v9.1!

Thank you!

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