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Scheduled sunlit fractions for windows

asked 2020-12-09 12:40:23 -0600

Jovanna's avatar

updated 2021-03-29 09:00:13 -0600

Hi everybody, I'm trying to import scheduled sunlit fraction for exterior surfaces (windows in particular). Following the "instructions" in the InputOutput reference manual, I'm setting the "Scheduled shading" in the "External Calculation Calculation Method" (ShadowCalculation class), and the schedule in the SurfaceProperty:LocalEnvironment class. However, when I'm asked to choose the exterior surface, only the "opaque" surfaces (defined in the BuildingSurface:Detailed class) can be chosen from the drop down menu. Referring to SurfaceProperty:LocalEnvironment, the InputOutput reference says: "The object links to a surface object Surface:Detailed". I'm creating the window in the FenestrationSurface:Detailed class; why thus I cannot choose the window as the exterior surface? (I've also tried to write the window surface name, but it was ignored and nothing happened checking the outputs). Has anyone experienced the same problem?

I was wondering if the scheduled values for the opaque surface (on which the window is settled) was used also for the windows, but I've checked the ouputs and for the opaque surface the scheduled value is used (I've set a constant value of 0 for a better understanding), while for the window the sunlit fractions are utocalculated by EnergyPlus. Any suggestion on how I can import scheduled sunlit fractions for windows (or alternative modelling approaches to get the same result)? Thanks!

PS. I'm using EnergyPlus version 9-0-0

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answered 2022-05-02 14:25:52 -0600

SurfaceProperty:LocalEnvironment can be applied to any surface, including fenestration surfaces. See example files SurfacePropTest_SurfLWR and SolarShadingTest_ExternalFraction. It is an IDD error that makes it appear in certain tools that you cannot apply this to a fenestration surface. See Issue 9275.

Also note that the "External Shading Fraction Schedule Name" should be named "Sunlit Fraction Schedule Name". See Issue 6935.

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Asked: 2020-12-09 12:40:23 -0600

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Last updated: May 02 '22