Thermochromic IDF Example Explanation

asked 2016-07-13 15:19:28 -0500

Adam Hilton gravatar image

updated 2017-05-03 20:44:51 -0500

Does anyone know why the idf example both in the Input Output Reference and the idf example file use different glazing materials all with the exact same properties for WindowMaterial:GlazingGroup:Thermochromic? I believe the solar transmittance should be decreasing for higher temperatures. I have provided two of the materials for here for quick comparison, all twelve look the same to me though.

Here is what is seen in the Input Output Reference....

 Construction,
    window_const,             !- Name
    Usual Glass,              !- Layer 1
    AIR 6MM,                  !- Layer 2
    TCGlazings,               !- Layer 3
    AIR 6MM,                  !- Layer 4
    Usual Glass;              !- Layer 5

  WindowMaterial:Gas,
    AIR 6MM,                 !- Name
    Air,                     !- Gas Type
    0.0063;                  !- Thickness {m}

! Added for thermochromic glazings
  WindowMaterial:GlazingGroup:Thermochromic,
    TCGlazings,
    0 ,  TCGlazing0,
    20,  TCGlazing20,
    25,  TCGlazing25,
    30,  TCGlazing30,
    35,  TCGlazing35,
    40,  TCGlazing40,
    45,  TCGlazing45,
    50,  TCGlazing50,
    55,  TCGlazing55,
    60,  TCGlazing60,
    65,  TCGlazing65,
    75,  TCGlazing75,
    85,  TCGlazing85;

WindowMaterial:Glazing,
  TCGlazing0,  !- Name
  SpectralAverage,  !- Optical Data Type
  ,        !- Window Glass Spectral Data Set Name
  0.0030,  !- Thickness
  0.2442,  !- Solar Transmittance at Normal Incidence
  0.7058,  !- Front Side Solar Reflectance at Normal Incidence
  0.7058,  !- Back Side Solar Reflectance at Normal Incidence
  0.3192,  !- Visible Transmittance at Normal Incidence
  0.6308,  !- Front Side Visible Reflectance at Normal Incidence
  0.6308,  !- Back Side Visible Reflectance at Normal Incidence
  0.0000,  !- Infrared Transmittance at Normal Incidence
  0.9000,  !- Front Side Infrared Hemispherical Emissivity
  0.9000,  !- Back Side Infrared Hemispherical Emissivity
  0.0199,  !- Conductivity
  1.0000,  !- Dirt Correction Factor for Solar and Visible Transmittance
  No;      !- Solar Diffusing

WindowMaterial:Glazing,
  TCGlazing20,  !- Name
  SpectralAverage,  !- Optical Data Type
  ,        !- Window Glass Spectral Data Set Name
  0.0030,  !- Thickness
  0.2442,  !- Solar Transmittance at Normal Incidence
  0.7058,  !- Front Side Solar Reflectance at Normal Incidence
  0.7058,  !- Back Side Solar Reflectance at Normal Incidence
  0.3192,  !- Visible Transmittance at Normal Incidence
  0.6308,  !- Front Side Visible Reflectance at Normal Incidence
  0.6308,  !- Back Side Visible Reflectance at Normal Incidence
  0.0000,  !- Infrared Transmittance at Normal Incidence
  0.9000,  !- Front Side Infrared Hemispherical Emissivity
  0.9000,  !- Back Side Infrared Hemispherical Emissivity
  0.0199,  !- Conductivity
  1.0000,  !- Dirt Correction Factor for Solar and Visible Transmittance
  No;      !- Solar Diffusing

EDIT: Here is what is seen in ThermochromicWindow.idf(This time just including the construction for the coldest (25°C) and warmest (85°C) temperatures) In this case the spectral data is slightly different for each window. Is that the correct way to handle the differences?

 Construction,
   TCwindow,                !- Name
   Clear3PPG,               !- Outside Layer
   AIR 3MM,                 !- Layer 2
   TCGlazings,              !- Layer 3
   AIR 8MM,                 !- Layer 4
   SB60Clear3PPG;           !- Layer 5

  WindowMaterial:GlazingGroup:Thermochromic,
    TCGlazings,              !- Name
    25,                      !- Optical Data Temperature 1 {C}
    WO18RT25,                !- Window Material Glazing Name 1
    27,                      !- Optical Data Temperature 2 {C}
    WO18RT27,                !- Window Material Glazing Name 2
    29,                      !- Optical Data Temperature 3 {C}
    WO18RT29,                !- Window Material Glazing Name 3
    31,                      !- Optical Data Temperature 4 {C}
    WO18RT31,                !- Window Material Glazing Name 4
    33,                      !- Optical Data Temperature 5 {C}
    WO18RT33,                !- Window Material Glazing Name 5
    35,                      !- Optical Data Temperature 6 {C}
    WO18RT35,                !- Window Material Glazing Name 6
    37,                      !- Optical Data Temperature 7 {C}
    WO18RT37,                !- Window ...
(more)
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Comments

What version of EnergyPlus? This is not what the currrent example file looks like.

Archmage gravatar image Archmage  ( 2016-07-14 08:21:01 -0500 )edit

What I quoted is from the Input Output Reference. Last I had checked actual idf example was in 8.4.

Adam Hilton gravatar image Adam Hilton  ( 2016-07-14 08:27:20 -0500 )edit