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Re: [EnergyPlus_Support] Re: COMIS & window transmitted solar
Modeling a completely open window is an interesting case. The windoglass
material module requires certain checks to be valid. My initial tests
generated several errors:
** Thermal transmittance + front thermal emissivity not < 1.0
** Thermal transmittance + back thermal emissivity not < 1.0
** Front solar reflectance not > 0.0 and < 1.0
** Back solar reflectance not > 0.0 and < 1.0
** Front visible reflectance not > 0.0 and < 1.0
** Back visible reflectance not > 0.0 and < 1.0
** Solar transmittance + front solar reflectance not < 1.0
** Solar transmittance + back solar reflectance not < 1.0
** Visible transmittance + front visible reflectance not < 1.0
** Visible transmittance + back visible reflectance not < 1.0
I finally ended up with this material:
MATERIAL:WINDOWGLASS,
Open Air, !- Name
SpectralAverage, !- Optical Data Type
, !- Name of Window Glass Spectral Data Set
.001, !- Thickness {m}
.99998, !- Solar Transmittance at Normal Incidence
.00001, !- Solar Reflectance at Normal Incidence: Front Side
.00001, !- Solar Reflectance at Normal Incidence: Back Side
.99998, !- Visible Transmittance at Normal Incidence
.00001, !- Visible Reflectance at Normal Incidence: Front Side
.00001, !- Visible Reflectance at Normal Incidence: Back Side
.99998, !- IR Transmittance at Normal Incidence
.00001, !- IR Hemispherical Emissivity: Front Side
.00001, !- IR Hemispherical Emissivity: Back Side
.00001, !- Conductivity {W/m-K}
1, !- Dirt Correction Factor for Solar and Visible Transmittance
No; !- Solar Diffusing
For the Chicago winter and summer design days, this results in an overall
transmittance of 0.989, reflectance of 0.0107, and absorptance of 0.0000176 for
most of the day.
Mike
On 19 Aug 2004, at 9:12, leeslwong wrote:
>
> Mike,
>
> If I want to the result of the mean air temperature of the room with
> ventilation and solar heat effect which is the real case I think, so
> that I
> should change the solar transmittance of the glass to 0.9999. Then,
> the
> temperature and the rate of thermal comfort will become more
> realistic
> situation of the room. Is it the correct way I can do?
>
> lee
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte"
> <mjwitte@g...> wrote:
> > The COMIS model only calculates infiltration and mixing flow rates,
> it has no
> > impact on the window solar calculations. So, you are correct, that
> the window
> > solar gain is modeled as if the windows are closed at all times.
> >
> > Mike
> >
> >
> > On 18 Aug 2004, at 11:42, leeslwong wrote:
> >
> > > Hi,
> > >
> > > I simulated a case that a room has 2 windows (one is facing to
> east
> > > and the other is facing to west). Using the COMIS method, the
> window
> > > are scheduled to open all the time. After the simulation, the air
> > > flow rates are normal and acceptable. But when I am looking at
> the
> > > window/zone transmitted solar, the result is adnormal because it
> is
> > > assumed the windows are still there (close). It is what I think.
> Is
> > > it the windows are still be closed when calculating transmitted
> solar
> > > and the windows are opened when calculating the COMIS ventilation
> at
> > > the same time? Or I am wrong?
> > >
> > > Thanks
> > >
> > > lee
> > >
> > >
> > >
> > >
> > > The primary EnergyPlus web site is found at:
> > > http://www.energyplus.gov
> > >
> > > The group web site is:
> > > http://groups.yahoo.com/group/EnergyPlus_Support/
> > >
> > > Attachments are not allowed -- please post any files to the
> appropriate folder
> > > in the Files area of the Support Web Site.
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> > ========================================================
> > Michael J. Witte, GARD Analytics, Inc.
> > EnergyPlus Testing and Support
> > EnergyPlus-Support@g...
>
>
>
>
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
>
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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