Output variable "Zone Interior Windows Total Transmitted Diffuse Solar Radiation Rate" (was "Zone Diff Solar from Interior Windows") may report incorrect values (or may be inconsistent with its definition). (CR #8834)

Possible reporting error for Zone Diff Solar from Interior Windows

Added on 2012-04-24 12:47 by @mjwitte

Description

MJW 24 Apr 2012 From user . . . On the example file attached, we have 4 zones behind a double skin zone. The problem is the smallest zone (Bloc1:Zone1) with the smallest internal window receives quite the same amount of Zone Diff Solar from Interior Windows [W] as biggest zones (BLoc1:Zone2,BLoc1:Zone3,BLoc4:Zone1).

It seems strange for windows area are very different!

Looking at zones Bloc1:Zone1 and Bloc1:Zone2

The ratio of interior window areas is 850 ft2/90ft2 = 9.4

The Ratio of ZoneDiff Solar from Interio Windows for these zones is about 1.3

Looking at "Total Shortwave Radiation Absorbed on Inside of Surface" instead, ratio is 3.6 - better but still much less than expected based on window areas.

See pictures and notes in spreadsheet

Inputs: 8834-* Weather: Chicago

TH 8/7/2012 Possible bug in SUBROUTINE ComputeDifSolExcZonesWIZWindows(NumberOfZones)

  DO SurfNum=1,TotSurfaces
    IF (.not. Surface(SurfNum)%HeatTransSurf) CYCLE
    IF (Surface(SurfNum)%ExtBoundCond <= 0) CYCLE
    IF (Surface(SurfNum)%ExtBoundCond  ==  SurfNum) CYCLE
    IF (Construct(Surface(SurfNum)%Construction)%TransDiff <= 0.0) CYCLE

    NZ=Surface(SurfNum)%Zone
    if (.not. Zone(NZ)%IntZWindow) CYCLE
    MZ=Surface(Surface(SurfNum)%ExtBoundCond)%Zone
    FractDifShortZtoZ(MZ,NZ)=FractDifShortZtoZ(MZ,NZ)+ &
                   Construct(Surface(SurfNum)%Construction)%TransDiff*VMULT(NZ)*Surface(SurfNum)%Area
    IF (VMULT(NZ) /= 0.0) RecDifShortFromZ(NZ)=.TRUE.
  END DO

correction: VMULT(NZ) should be VMULT(MZ)

Workaround

To determine total solar gains retained in a zone, use output variable "Surface Inside Face Absorbed Shortwave Radiation Rate" (was "Total Shortwave Radiation Absorbed on Inside of Surface") then sum across all surfaces in the zone.

External Ref: Ticket 5289 Last build tested: 12.04.17 V7.1.0.008

NREL / EnergyPlus